The American Journal of Sports Medicine

The initial graft tension applied at the time of anterior cruciate ligament (ACL) reconstruction alters joint contact and may influence cartilage health. The objective was to compare outcomes between 2 commonly used “laxity-based” initial graft tension protocols.

(1) The high-tension group would have less knee laxity, improved clinical and patient-oriented outcomes, and less cartilage damage than would the low-tension group after 36 months of healing. (2) The outcomes of the high-tension group would be equivalent to those of a matched control group.

Randomized controlled trial; Level of evidence, 1.

Ninety patients with isolated unilateral ACL injuries were randomized to undergo ACL reconstruction using 1 of 2 initial graft tension protocols: (1) autografts tensioned to restore normal anterior-posterior (AP) laxity at the time of surgery (ie, low tension; n = 46) and (2) autografts tensioned to overconstrain AP laxity by 2 mm (ie, high tension; n = 44). Sixty matched healthy patients formed the control group. Outcomes were assessed preoperatively, intraoperatively, and at 6, 12, and 36 months after surgery.

No significant differences were found between the 2 initial graft tension protocols for any of the outcome measures at 36 months. However, there were differences when comparing the 2 treatment groups to the control group. On average, AP laxity was 2 mm greater in the ACL-reconstructed groups than in the control group (P < .007). International Knee Documentation Committee (IKDC) knee evaluation scores, peak isokinetic knee extension torques, and 4 of 5 Knee Osteoarthritis Outcome Scores (KOOS) were significantly worse than the control group (P < .001, P < .027, and P < .05, respectively). Short Form–36 Health Survey (SF-36) scores and reinjury rates were similar between groups at 36 months. Although there were significant changes in radiography and magnetic resonance imaging present in the ACL-reconstructed knees of both treatment groups, the magnitude was relatively small and likely clinically insignificant at 36 months.

Both laxity-based initial graft tension protocols produced similar outcomes without fully restoring joint function or patient-oriented outcomes (KOOS) when compared with the control group. There was minimal evidence of cartilage damage 36 months after surgery.

Consistent radiographic guidelines for tunnel placement in single- or double-bundle posterior cruciate ligament (PCL) reconstructions are not well defined. Quantitative guidelines reporting the location of the individual PCL bundle attachments would aid in intraoperative tunnel placement and postoperative assessment of a PCL reconstruction.

Consistent and reproducible measurements in relation to radiographic landmarks for the entire PCL and its individual bundle attachments are achievable.

Controlled laboratory study.

The femoral and tibial PCL bundle attachment centers of 20 nonpaired fresh-frozen cadaveric knees were labeled using radio-opaque spheres and the attachment areas were labeled using barium sulfate. Anteroposterior (AP) and lateral radiographs of the femur and tibia were obtained, and measurements of the distances between the PCL bundle centers and landmarks were acquired.

On the AP femur view, the anterolateral bundle (ALB) and posteromedial bundle (PMB) centers were 34.1 ± 3.0 mm and 29.2 ± 3.0 mm lateral to the most medial border of the medial femoral condyle, respectively. The lateral femur images revealed that the ALB center was 17.4 ± 1.7 mm and the PMB center was 23.9 ± 2.7 mm posteroproximal to a line perpendicular to the Blumensaat line that intersected the anterior margin of the medial femoral condyle cortex. Anteroposterior tibia images revealed that the ALB and PMB centers were located 0.2 ± 2.1 mm proximal and 4.9 ± 2.9 mm distal to the proximal joint line, respectively. The PCL attachment center was 1.6 ± 2.5 mm distal to the proximal joint line. On the lateral tibia view, the ALB center was 8.4 ± 1.8 mm, the PCL attachment center was 5.5 ± 1.7 mm, and the PMB center was 2.5 ± 1.5 mm superior to the champagne glass drop-off of the posterior tibia.

Radiographic measurements from several clinically relevant views of the femur and tibia were reproducible with regard to the anatomic locations of the ALB and PMB centers. The measurements from the lateral femur and tibia views provided the most clinically pertinent radiographic measurements intraoperatively.

This study established a set of clinically relevant radiographic guidelines for anatomic reconstruction of the PCL. The parameters set forth in this study can be used in both the intraoperative and postoperative settings for both single- and double-bundle PCL reconstructions.

During posterior cruciate ligament (PCL) reconstruction, the placement and orientation of the femoral tunnel is critical to postoperative PCL function.

To compare the ability of outside-in (OI) versus inside-out (IO) femoral tunnel drilling in placing the femoral tunnel aperture within the anatomic femoral footprint of the PCL, and to evaluate the orientation of the tunnels within the medial femoral condyle.

Controlled laboratory study.

Ten matched pairs of cadaver knees were randomized such that within each pair, 1 knee underwent arthroscopic OI drilling and the other underwent IO drilling. All knees underwent computed tomography (CT) both pre- and postoperatively with a technique optimized for ligament evaluation (80 keV with maximum mAs). Commercially available third-party software was used to fuse the pre- and postoperative CT scans, allowing comparison of the PCL footprint to the drilled tunnel. The percentage of tunnel aperture contained within the native footprint, as well as the distance from the center of the tunnel aperture to the center of the footprint, were measured. In addition, the orientation of the tunnels in the coronal and axial planes was evaluated.

The OI technique placed 70.4% ± 23.7% of the tunnel within the native femoral footprint compared with 79.8% ± 16.7% for the IO technique (P = .32). The OI technique placed the center of the femoral tunnel 4.9 ± 2.2 mm from the center of the native footprint compared to 5.3 ± 2.0 mm for the IO technique (P = .65). The femoral tunnel angle in the coronal plane was 21.0° ± 9.9° for the OI technique and 37.0° ± 10.3° for the IO technique (P = .002). The tunnel angle in the axial plane was 27.3° ± 4.8° for the OI technique and 39.1° ± 11.5° for the IO technique (P = .01).

This study demonstrates no difference in the ability of the OI and IO techniques to place the femoral tunnel within the PCL femoral footprint during PCL reconstruction. With the technique parameters used in this study, the IO technique created femoral tunnels with a more vertical and anterior orientation than the OI technique.

Either technique can be used to place the femoral tunnel within the anatomic footprint. Consideration should be given to tunnel orientation following each technique, and what effect it has on graft bending angles, as these characteristics may affect graft strain and, ultimately, graft failure. In this regard, the IO technique likely produces gentler graft bending angles.

The role of anatomic risk factors in patellofemoral instability is not yet fully understood, as they have been observed in patients either alone or in combination and in different degrees of severity.

To prospectively analyze rotational limb alignment in patients with patellofemoral instability and in controls using magnetic resonance imaging (MRI).

Cross-sectional study; Level of evidence, 3.

Thirty patients (mean age, 22.9 y; range, 12-41 y) with a history of patellar dislocation and 30 age- and sex-matched controls (mean age, 25.2 y; range, 16-37 y) were investigated. The patients underwent MRI of the leg at 1.5 T using a peripheral angiography coil and a T2-weighted half-Fourier acquisition single-shot turbo spin echo (HASTE) sequence for measuring femoral antetorsion, tibial torsion, knee rotation, and mechanical axis deviation (MAD). The mean values of these parameters were compared between patients and controls. In addition, the patients underwent an assessment to determine the influence of rotational limb alignment on lateral trochlear inclination, trochlear facet asymmetry, trochlear depth, Insall-Salvati index, and tibial tuberosity–trochlear groove distance.

Patients had 1.56-fold higher mean femoral antetorsion (20.3° ± 10.4° vs 13.0° ± 8.4°; P < .01) and 1.6-fold higher knee rotation (9.4° ± 5.0° vs 5.7° ± 4.3°; P < .01) compared with controls. Moreover, patients had 2.9 times higher MAD (0.81 ± 0.75 mm vs −0.28 ± 0.87 mm; P < .01). Differences in tibial torsion were not significant. Also, there were no significant correlations between parameters of rotational alignment and standard anatomic risk factors.

Our results suggest that some patients with nontraumatic patellar instability have greater internal femoral rotation, greater knee rotation, and a tendency for genu valgum compared with healthy controls. Rotational malalignment may be a primary risk factor in patellar dislocation that has so far been underestimated.

Recurrent lateral patellar dislocation is a common knee injury in the skeletally immature adolescent. Because of the open physis, operative therapy in children is challenging. This study presents the outcomes of a minimally invasive technique for anatomic reconstruction of the medial patellofemoral ligament (MPFL) in children that respects the distal femoral physis.

Anatomic reconstruction of the MPFL in children that maintains the distal femoral physis will prevent redislocation, preserve the distal femoral physis, and improve knee function.

Case series; Level of evidence, 4.

Twenty-one consecutive patients with patellofemoral instability and open growth plates underwent anatomic reconstruction of the MPFL that maintained the distal femoral growth plate. Preoperative radiographic examination included AP and lateral views to assess patella alta and limb alignment. Magnetic resonance imaging was performed to evaluate trochlear dysplasia and tibial tubercle–trochlear groove (TT-TG) distance. Evaluation included preoperative and postoperative physical examination, Kujala score, and Tegner activity score.

The average age at the time of operation was 12.2 years (range, 10.3-13.9). The average follow-up after operation was 2.8 years after surgery (range, 2.0-3.6). No recurrent dislocation occurred, but 2 patients with high-grade trochlear dysplasia still had a positive apprehension sign. The Kujala score significantly improved from 72.9 (range, 37-87) preoperatively to 92.8 (range, 74-100) postoperatively (P < .01). The Tegner activity score decreased, but not significantly, from 6.0 (range, 3-9) preoperatively to 5.8 (range, 3-9) postoperatively (P = .48).

Anatomic reconstruction of the MPFL that respects the distal femoral physis in skeletally immature patients is a safe and effective technique for the treatment of patellofemoral instability and allows patients to return to sports without redislocation of the patella.

Little is known about radial displacement (RD) of polyurethane (PU) scaffolds, intended for partial meniscus defect substitution; no data are available on whether rim thickness influences RD and whether RD correlates with clinical outcome scores.

The meniscus is not extruded preoperatively, but RD occurs after scaffold implantation. A thicker rim will limit RD, and there is no correlation between RD and clinical outcome.

Case series; Level of evidence, 4.

Twenty-six patients were implanted with a PU scaffold (8 lateral, 18 medial). Radial displacement (mm) was evaluated on magnetic resonance images preoperatively and at 3 months, 1 year, and 2 years postoperatively. At each time point, it was determined whether a correlation existed between the rim and RD. Clinical outcome was determined using a visual analog scale (VAS) for pain as well as the Lysholm knee scoring scale, Knee Injury and Osteoarthritis Outcome Score (KOOS), and International Knee Documentation Committee (IKDC) score.

Radial displacement of lateral scaffolds was not significantly different (P = .178) either preoperatively (mean ± SD, 3.42 ± 0.99 mm) or at 3 months (4.82 ± 0.59 mm), 1 year (4.55 ± 0.87 mm), or 2 years postoperatively (4.10 ± 0.93 mm). No correlation was observed between the rim and lateral RD at all time points. Medial scaffold RD increased significantly (P < .001) from preoperative values (2.17 ± 0.84 mm) to those at 3 months (4.25 ± 0.89 mm), 1 year (4.43 ± 1.01 mm), and 2 years postoperatively (4.41 ± 0.96 mm). A strong negative correlation between medial RD and the rim was observed at all time points. There was no significant correlation between clinical outcome scores and RD, either preoperatively or postoperatively.

This study demonstrated that limited medial meniscal RD was present preoperatively but increased by 2 mm after scaffold implantation. Lateral RD was also present preoperatively but did not increase after scaffold implantation. Importantly, a strong negative correlation was found between the rim and postoperative medial RD; a thicker rim limited RD. However, in the lateral compartment, rim thickness did not correlate with RD because RD was already strongly present preoperatively. Finally, no correlations were observed between scaffold RD and clinical outcome scores, either preoperatively or postoperatively.

There is still little known regarding the effects of meniscus resection size on tibiofemoral stability.

To determine if partial medial meniscectomy of the posterior horn significantly alters tibiofemoral stability as measured by the anterior-posterior (AP) position and laxity of the medial femoral condyle.

Controlled laboratory study.

Five cadaveric knees were dissected to the capsule, preserving all ligaments and the quadriceps tendon. Each specimen was first tested on a rig where the AP position and laxity of the medial femoral condyle were measured while a range of forces was applied from full extension to 90° of flexion. Magnetic resonance imaging (MRI) at 3 tesla was then performed for baseline measurements of the meniscus before partial meniscectomy. Arthroscopic partial medial meniscectomy aimed at 30% of the posterior horn was then performed, followed by repeat mechanical testing and MRI. The sequence was then repeated for arthroscopic partial meniscectomy aimed at 60% and 100% of the posterior horn of the medial meniscus.

The MRI analysis demonstrated that 22% ± 9% of the original width of the posterior horn was removed at the first resection, 46% ± 11% was removed at the second resection, and the third resection was 100% removal of the posterior horn for all specimens. After 22% resection, no significant difference in AP laxity was observed. A statistically significant increase in AP laxity was observed with 46% resection under a 500-N compressive load compared with the intact meniscus. After full resection, significant increases in AP laxity were observed under a 50-N compressive load compared with the intact and 22% and 46% resections. The 22% resection had similar AP positions as the intact knee, whereas the 46% resection and 100% removal of the posterior horn had statistically further posterior AP positions than the intact knee.

Partial medial meniscectomy with ≥46% resection of the original width of the posterior horn significantly altered the AP position of the medial femoral condyle and also increased laxity.

These mechanical changes may lead to abnormal cartilage loading and early osteoarthritis.

It has been suggested that patellofemoral contact pressures and contact forces may be altered secondary to an opening wedge high tibial osteotomy, yet few data are available that quantify the effect of varying degrees of medial opening wedge osteotomy on the patellofemoral joint contact characteristics.

Opening wedge medial proximal tibial osteotomy will increase patellofemoral contact force and pressure.

Controlled laboratory study.

Nine human cadaver knees were used. Pressure-sensitive film was placed in the suprapatellar pouch, leaving the patellar tendon and medial and lateral retinacula intact. The quadriceps tendon was attached to a materials testing machine along the axis of the femur, whereby a pulley mechanism generated 950 N of force. Patellofemoral contact characteristics were measured with pressure-sensitive film at 30°, 60°, 90°, and 120° of flexion for the native knee and after subsequent 10-mm and 15-mm medial opening wedge proximal tibial osteotomies. The film was analyzed with imaging software.

There was a statistically significant increase (P < .05) in mean contact pressure at 30° and 120° between the 10-mm osteotomy and native knee and across all flexion angles between the 15-mm osteotomy and native knee. Furthermore, a significant difference was seen in peak pressures when native knees were compared with 10-mm and 15-mm opening wedge osteotomies at all flexion angles.

There was a significant increase in patellofemoral pressures at varying degrees of knee flexion after medial opening wedge proximal tibial osteotomies of only 10 mm; a larger osteotomy resulted in a greater increase.

When performing a medial opening wedge proximal tibial osteotomy, the surgeon should consider the negative effects of increased patellofemoral peak pressure.

The dial test can be improved by providing reproducible, accurate measurements to improve diagnosis and treatment comparisons.

Validation of a rotational measurement device (RMD) for measuring knee internal-external rotational laxity.

Cohort study (diagnosis); Level of evidence, 2.

The RMD consisted of 3 components: a femoral clamp and a tibial splint using paired inclinometers to measure rotations, and a boot to apply tibial internal-external rotation torque. A separate boot inclinometer allowed for foot rotations to be measured independently. The measurements were simultaneously compared with electromagnetic “nest of birds” (NOB) sensors. Sequential paired knee measurements were taken at 4, 6, and 8 N·m of torque at 30° and 90° of flexion in 46 volunteers.

The correlation coefficient was 0.92 (95% CI, 0.89 to 0.94) and 0.63 (95% CI, 0.54 to 0.70) between the NOB and RMD and between the NOB and boot inclinometer, respectively. Bland-Altman analysis revealed that the RMD was on average within 2° (95% CI, 1° to −4°) of NOB readings, whereas the boot overestimated by 34° (95% CI, −9° to −58°). Maximum side-to-side differences measured by the NOB, RMD, and boot were 1°, 3°, and 21°, respectively. The mean +2× standard deviation data gave a range of side-to-side differences of less than 5° for the RMD. The intraobserver intraclass correlation was 0.9 (95% CI, 0.78 to 0.97) at both 30° and 90° of flexion, and the 95% CI of the differences between readings taken on 2 occasions, the interobserver repeatability, was 1° or less.

The novel clinical RMD for measuring rotational laxity of the knee was portable, easy, and comfortable to use in the clinical setting. The RMD showed significant correlation and accuracy compared with sensors of known high accuracy. Side-to-side differences of less than 5° were found in 95% of normal knees, compared with differences of 13° or more for clinical diagnosis of pathological rotational laxity. Measuring knee rotation at the foot showed poor correlation and accuracy.

Young patients with osteoarthritic knees are a challenging population because of a combination of high functional demands and limited indication for joint replacement.

To analyze the potential of the cartilage regenerative approach by documenting the results and failures of matrix-assisted autologous chondrocyte transplantation (MACT) at midterm follow-up.

Case series; Level of evidence, 4.

Forty-four patients affected by cartilage lesions in osteoarthritic knees underwent MACT as a salvage procedure. The mean age at surgery was 42 years (range, 20-58 years), and the average defect size was 4 cm² (range, 1.5-9 cm²). Patients were prospectively evaluated with the subjective International Knee Documentation Committee (IKDC), EuroQol visual analog scale (EQ-VAS), and Tegner scores preoperatively; at 1, 2, and 5 years; and at a final assessment at 9 years’ mean follow-up. Adverse events and failures were also reported.

A statistically significant improvement was observed in all scores from the initial evaluation to the final follow-up. The mean ± standard deviation IKDC subjective score improved from 38.0 ± 15.8 to 67.0 ± 18.3 at 2 years (P < .0005), with a subsequent decrease to 57.8 ± 20.6 at the final follow-up (P = .012). The same trend was confirmed by the EQ-VAS score. The activity level revealed by the Tegner score improved at all follow-ups but without achieving the preinjury level. The analysis of the influencing factors showed the importance of the meniscus condition, revealing a significantly inferior outcome in knees with previous or combined partial meniscectomy procedures. During the study period, 12 patients had failed results, producing a cumulative failure rate of 27.3%. At the last evaluation, half of the patients considered their condition not better than before the treatment, and 39% would not repeat the treatment considering the results obtained.

Despite a statistically significant improvement, the clinical outcome was poor. A higher improvement could be obtained in patients who had not undergone previous or combined meniscectomies, but this was limited over time. The failure rate was also high, regardless of the degree of osteoarthritis. Tissue-engineered cartilage implantation is questionable for this indication, and the limits of this scaffold-based procedure have to be considered if it is used as a salvage procedure for young patients affected by knee osteoarthritis.

Previous reports have shown that graft fixation with the Endobutton is associated with tunnel widening because it provides distant fixation rather than aperture fixation.

A longer loop of the Endobutton results in greater tunnel widening than a shorter loop.

Cohort study; Level of evidence, 3.

A total of 171 consecutive patients underwent hamstring anterior cruciate ligament (ACL) reconstruction fixed with the Endobutton. They were followed for a minimum of 2 years postoperatively. A 15-mm loop was used in 20 patients, a 20-mm loop in 53, a 25-mm loop in 58, and a >30-mm loop in 40. On anterior-posterior (AP) and lateral radiographs, the measured diameters of the femoral tunnel at 2 years after surgery were compared with the diameter of the reamer used at surgery. The measured diameter of the tibial tunnel at 2 years after surgery was compared with measurements taken on the immediate postoperative day. The center of the tibial tunnel and direction of the ACL graft were also measured. Postoperative knee stability was evaluated using the Lachman test, pivot-shift test, and KT-1000 arthrometer. Functional evaluations were performed using the Lysholm score and Tegner activity scale. All measurements were compared among the 4 groups according to the length of the Endobutton loop.

The mean ± standard deviation (SD) diameter of the femoral tunnel increased by 50.7% ± 23.3% and 37.0% ± 18.8% on AP and lateral radiographs at 2 years after surgery, respectively. The mean ± SD diameter of the tibial tunnel increased by 40.8% ± 19.3% and 46.4% ± 22.6% on AP and lateral radiographs, respectively. No significant difference in tunnel widening was present according to the length of the Endobutton loop. There were no significant differences in the average center of the tibial tunnel or the average angle of the direction of the ACL graft among the 4 groups. There was no significant difference in Lachman test results, postoperative KT-1000 arthrometer side-to-side differences, Lysholm score, and Tegner activity scale score among the 4 groups. The group with a >30-mm loop showed a significant difference in the pivot-shift test than the other 3 groups (P = .023).

A longer Endobutton loop did not result in greater tunnel widening than a shorter loop. Long fixation distance may not be associated with tunnel widening after hamstring ACL reconstructions.

Athletic pubalgia is a complex injury that results in loss of play in competitive athletes, especially hockey players. The number of reported sports hernias has been increasing, and the importance of their management is vital. There are no studies reporting whether athletes can return to play at preinjury levels.

The focus of this study was to evaluate the productivity of professional hockey players before an established athletic pubalgia diagnosis contrasted with the productivity after sports hernia repair.

Cohort study; Level of evidence, 3.

Professional National Hockey League (NHL) players who were reported to have a sports hernia and who underwent surgery from 2001 to 2008 were identified. Statistics were gathered on the players’ previous 2 full seasons and compared with the statistics 2 full seasons after surgery. Data concerning games played, goals, average time on ice, time of productivity, and assists were gathered. Players were divided into 3 groups: group A incorporated all players, group B were players with 6 or fewer seasons of play, and group C consisted of players with 7 or more seasons of play. A control group was chosen to compare player deterioration or improvement over a career; each player selected for the study had a corresponding control player with the same tenure in his career and position during the same years.

Forty-three hockey players were identified to have had sports hernia repairs from 2001 to 2008; ultimately, 80% would return to play 2 or more full seasons. Group A had statistically significant decreases in games played, goals scored, and assists. Versus the control group, the decreases in games played and assists were supported. Statistical analysis showed significant decreases in games played, goals scored, assists, and average time on ice the following 2 seasons in group C, which was also seen in comparison with the control group. Group B (16 players) showed only statistical significance in games played versus the control group.

Players who undergo sports hernia surgeries return to play and often perform similar to their presurgery level. Players with over 7 full seasons return but with significant decreases in their overall performance levels. Less veteran players were able to return to play without any statistical decrease in performance and are likely the best candidates for repair once incurring injury.

The hamstring muscles are the most commonly injured muscle group in many different sports. Recovery time is often unpredictable and prolonged, and recurrent injury is common.

Hamstring injuries that disrupt the central tendon enclosed within the muscle belly require a longer recovery time than do injuries involving only muscle, epimysial fascia, or the musculotendinous junction.

Cohort study; Level of evidence, 3.

Injury records from professional sports teams were reviewed to determine the length of recovery from each hamstring injury that occurred over a 24-month period. The integrity of the central tendon on magnetic resonance imaging (MRI) was retrospectively reviewed for each case. The association between central tendon disruption on MRI and recovery time was determined.

There were 62 hamstring injuries included for analysis; 45 (72%) involved the biceps femoris, 11 (18%) involved the semimembranosus, and 6 (10%) involved the semitendinosus. Central tendon disruption was identified in 12 (45%) of the biceps femoris injuries and in none of the injuries to the other 2 muscles. Three of these injuries were treated surgically, with a median recovery time of 91 days. The median (interquartile range [IQR]) recovery times for those remaining biceps femoris injuries with and without central tendon disruption were 21 days (IQR, 9-28) and 72 days (IQR, 42-109), respectively (P < .01).

Disruption of the central tendon in injuries to the biceps femoris results in a significantly longer recovery time than injuries that do not disrupt the central tendon. This highlights the distinction between injury to the hamstring muscle and injury to the hamstring tendon, which is underappreciated as being a distinct entity when injury involves the enclosed central portion of the tendon.

The effect of prior strain injury on myoelectrical activity of the hamstrings during tasks requiring high rates of torque development has received little attention.

To determine if recreational athletes with a history of unilateral hamstring strain injury will exhibit lower levels of myoelectrical activity during eccentric contraction, rate of torque development (RTD), and impulse (IMP) at 30, 50, and 100 milliseconds after the onset of myoelectrical activity or torque development in the previously injured limb compared with the uninjured limb.

Case control study; Level of evidence, 3.

Twenty-six recreational athletes were recruited. Of these, 13 athletes had a history of unilateral hamstring strain injury (all confined to biceps femoris long head), and 13 had no history of hamstring strain injury. Following familiarization, all athletes undertook isokinetic dynamometry testing and surface electromyography (integrated EMG; iEMG) assessment of the biceps femoris long head and medial hamstrings during eccentric contractions at −60 and −180 deg·s⁻¹.

In the injured limb of the injured group, compared with the contralateral uninjured limb, RTD and IMP was lower during −60 deg·s⁻¹ eccentric contractions at 50 milliseconds (RTD: injured limb, 312.27 ± 191.78 N·m·s⁻¹ vs uninjured limb, 518.54 ± 172.81 N·m·s⁻¹, P = .008; IMP: injured limb, 0.73 ± 0.30 N·m·s vs uninjured limb, 0.97 ± 0.23 N·m·s, P = .005) and 100 milliseconds (RTD: injured limb, 280.03 ± 131.42 N·m·s⁻¹ vs uninjured limb, 460.54 ± 152.94 N·m·s⁻¹, P = .001; IMP: injured limb, 2.15 ± 0.89 N·m·s vs uninjured limb, 3.07 ± 0.63 N·m·s, P < .001) after the onset of contraction. Biceps femoris long head muscle activation was lower at 100 milliseconds at both contraction speeds (–60 deg·s⁻¹, normalized iEMG activity [×1000]: injured limb, 26.25 ± 10.11 vs uninjured limb, 33.57 ± 8.29, P = .009; –180 deg·s⁻¹, normalized iEMG activity [×1000]: injured limb, 31.16 ± 10.01 vs uninjured limb, 39.64 ± 8.36, P = .009). Medial hamstring activation did not differ between limbs in the injured group. Comparisons in the uninjured group showed no significant between limbs difference for any variables.

Previously injured hamstrings displayed lower RTD and IMP during slow maximal eccentric contraction compared with the contralateral uninjured limb. Lower myoelectrical activity was confined to the biceps femoris long head. Regardless of whether these deficits are the cause of or the result of injury, these findings could have important implications for hamstring strain injury and reinjury. Particularly, given the importance of high levels of muscle activity to bring about specific muscular adaptations, lower levels of myoelectrical activity may limit the adaptive response to rehabilitation interventions and suggest that greater attention be given to neural function of the knee flexors after hamstring strain injury.

Uncontained osteochondral lesions of the talar shoulder are associated with an increased risk of clinical failure in patients treated with current cylindrical osteochondral autograft techniques. Whether the same holds true in patients undergoing arthroscopic treatment is unknown.

To determine the relative prognostic significance of the containment (shoulder vs nonshoulder type) and location (medial vs lateral) of an osteochondral lesion of the talus (OLT).

Arthroscopic treatment may not be ideal for uncontained lesions of the talar shoulder due to a lack of structural support.

Cohort study; Level of evidence, 3.

Arthroscopic treatment for OLT was performed on the ankles of 399 patients between 2001 and 2009. Analyses were performed by grouping the patients according to type of containment (shoulder, n = 181; nonshoulder, n = 218), location (medial, n = 274; lateral, n = 125), and both type of containment and location (medial shoulder, n = 129; medial nonshoulder, n = 145; lateral shoulder, n = 52; lateral nonshoulder, n = 73). To evaluate the role of containment and location independently of OLT size, patients were grouped according to quartile of defect size, and outcomes were analyzed within each group.

Patients with shoulder-type OLT had a substantially worse clinical outcome than did those with nonshoulder-type OLT, even after adjustment for OLT size (P < .05). However, there was no significant difference in clinical outcome between patients with medial OLT and those with lateral OLT, and the clinical failure rates of the 2 groups were similar (P > .05). A Cox proportional hazards regression model demonstrated that OLT containment, but not location, exerted an independent prognostic effect.

Patients with uncontained OLT of the talar shoulder experienced a more complicated clinical outcome than did those with contained, nonshoulder-type OLT even after adjustment for OLT size and regardless of location.

Ten to seventy percent of rotator cuff repairs form a recurrent defect after surgery. The relationship between retraction of the repaired tendon and formation of a recurrent defect is not well defined.

To measure the prevalence, timing, and magnitude of tendon retraction after rotator cuff repair and correlate these outcomes with formation of a full-thickness recurrent tendon defect on magnetic resonance imaging, as well as clinical outcomes. We hypothesized that (1) tendon retraction is a common phenomenon, although not always associated with a recurrent defect; (2) formation of a recurrent tendon defect correlates with the timing of tendon retraction; and (3) clinical outcome correlates with the magnitude of tendon retraction at 52 weeks and the formation of a recurrent tendon defect.

Case series; Level of evidence, 4.

Fourteen patients underwent arthroscopic rotator cuff repair. Tantalum markers placed within the repaired tendons were used to assess tendon retraction by computed tomography scan at 6, 12, 26, and 52 weeks after operation. Magnetic resonance imaging was performed to assess for recurrent tendon defects. Shoulder function was evaluated using the Penn score, visual analog scale (VAS) score for pain, and isometric scapular-plane abduction strength.

All rotator cuff repairs retracted away from their position of initial fixation during the first year after surgery (mean [standard deviation], 16.1 [5.3] mm; range, 5.7-23.2 mm), yet only 30% of patients formed a recurrent defect. Patients who formed a recurrent defect tended to have more tendon retraction during the first 6 weeks after surgery (9.7 [6.0] mm) than those who did not form a defect (4.1 [2.2] mm) (P = .08), but the total magnitude of tendon retraction was not significantly different between patient groups at 52 weeks. There was no significant correlation between the magnitude of tendon retraction and the Penn score (r = 0.01, P = .97) or normalized scapular abduction strength (r = −0.21, P = .58). However, patients who formed a recurrent defect tended to have lower Penn scores at 52 weeks (P = .1).

Early tendon retraction, but not the total magnitude, correlates with formation of a recurrent tendon defect and worse clinical outcomes. “Failure with continuity” (tendon retraction without a recurrent defect) appears to be a common phenomenon after rotator cuff repair. These data suggest that repairs should be protected in the early postoperative period and repair strategies should endeavor to mechanically and biologically augment the repair during this critical early period.

Modern techniques for the treatment of acromioclavicular (AC) joint dislocations have largely centered on free tendon graft reconstructions. Recent biomechanical studies have demonstrated that an anatomic reconstruction with 2 clavicular bone tunnels more closely matches the properties of native coracoclavicular (CC) ligaments than more traditional techniques. No study has analyzed tunnel position in regard to risk of early failure.

To evaluate the effect of clavicular tunnel position in CC ligament reconstruction as a risk of early failure.

Case series; Level of evidence, 4.

A retrospective review was performed of a consecutive series of CC ligament reconstructions performed with 2 clavicular bone tunnels and a free tendon graft. The population was largely a young, active-duty military group of patients. Radiographs were analyzed for the maintenance of reduction and location of clavicular bone tunnels using a picture archiving and communication system. The distance from the lateral border of the clavicle to the center of each bone tunnel was divided by the total clavicular length to establish a ratio. Medical records were reviewed for operative details and functional outcome. Failure was defined as loss of intraoperative reduction.

The overall failure rate was 28.6% (8/28) at an average of 7.4 weeks postoperatively. Comparison of bone tunnel position showed that medialized bone tunnels were a significant predictor for early loss of reduction for the conoid (a ratio of 0.292 vs 0.248; P = .012) and trapezoid bone tunnels (a ratio of 0.171 vs 0.128; P = .004); this correlated to an average of 7 to 9 mm more medial in the reconstructions that failed. Reconstructions performed with a conoid ratio of ≥0.30 were significantly more likely to fail (5/5, 100%) than were those performed lateral to a ratio of 0.30 (3/23, 13.0%) (P < .01). There were no failures when the conoid ratio was <0.25 (0/10, 0%). Conoid tunnel placement was also statistically significant for predicting return to duty in our active-duty population.

Medial tunnel placement is a significant factor in risk for early failures when performing anatomic CC ligament reconstructions. Preoperative templating is recommended to evaluate optimal placement of the clavicular bone tunnels. Placement of the conoid tunnel at 25% of the clavicular length from the lateral border of the clavicle is associated with a lower rate of lost reduction and a higher rate of return to military duty.

Injection to the acromioclavicular (AC) joint can be both diagnostic and therapeutic.

The purpose of this study was to evaluate the accuracy of in vivo AC joint injections.

Case series; Level of evidence, 4.

Thirty patients with pain localized to the AC joint were injected with 1 mL of 1% lidocaine and 0.5 mL of radiographic contrast material (Isovue). Radiographs of the AC joint were taken after the injection. Each radiograph was reviewed by a musculoskeletal radiologist and graded as intra-articular, extra-articular, or partially intra-articular.

Of the 30 injections performed, 13 (43.3%) were intra-articular, 7 (23.3%) were partially articular, and 10 (33.3%) were extra-articular. When the intra-articular and the partially articular groups were combined, 20 patients (66.7%) had some contrast dye in the AC joint.

This study demonstrates that despite the relatively superficial location of the AC joint, the clinical accuracy of AC joint injections remains relatively low.

The double-row suture bridge repair was recently introduced and has demonstrated superior biomechanical results and higher yield load compared with the traditional double-row technique. It therefore seemed reasonable to compare this second generation of double-row constructs to the modified single-row double mattress reconstruction.

The repair technique, initial tear size, and tendon subregion will have a significant effect on 3-dimensional (3D) cyclic displacement under additional static external rotation of a modified single-row compared with a double-row rotator cuff repair.

Controlled laboratory study.

Rotator cuff tears (small to medium: 25 mm; medium to large: 35 mm) were created in 24 human cadaveric shoulders. Rotator cuff repairs were performed as modified single-row or double-row repairs, and cyclic loading (10-60 N, 10-100 N) was applied under 20° of external rotation. Radiostereometric analysis was used to calculate cyclic displacement in the anteroposterior (x), craniocaudal (y), and mediolateral (z) planes with a focus on the repair constructs and the initial tear size. Moreover, differences in cyclic displacement of the anterior compared with the posterior tendon subregions were calculated.

Significantly lower cyclic displacement was seen in small to medium tears for the single-row compared with double-row repair at 60 and 100 N in the x plane (P = .001) and y plane (P = .001). The results were similar in medium to large tears at 100 N in the x plane (P = .004). Comparison of 25-mm versus 35-mm tears did not show any statistically significant differences for the single-row repairs. In the double-row repairs, lower gap formation was found for the 35-mm tears (P ≤ .05). Comparison of the anterior versus posterior tendon subregions revealed a trend toward higher anterior gap formation, although this was statistically not significant.

The tested single-row reconstruction achieved superior results in 3D cyclic displacement to the tested double-row repair. Extension of the initial rupture size did not have a negative effect on the biomechanical results of the tested constructs.

Single-row repairs with modified suture configurations provide comparable biomechanical strength to double-row repairs. Furthermore, as increased gap formation in the early postoperative period might lead to failure of the construct, a strong anterior fixation and restricted external rotation protocol might be considered in rotator cuff repairs to avoid this problem.

Bankart repair with multiple anchor holes concentrated in the anterior-inferior glenoid may contribute to glenoid weakening and potentially may induce glenoid failure.

To compare the biomechanical strength of a Bankart repair construct that used 3 single-loaded suture anchors versus a repair construct that used 2 double-loaded suture anchors.

Comparative laboratory study.

A standard Bankart lesion was created in 18 human cadaveric shoulders (9 matched pairs). Within each matched pair, 1 repair construct used 3 single-loaded anchors, whereas the other used 2 double-loaded suture anchors. Measured outcomes (load, stiffness, and energy absorbed) were recorded at failure and at 2 mm of labral displacement. Constructs were loaded to failure with a materials testing device that had differential variable reluctance transducers for displacement measurements.

The double-loaded anchor construct had a significantly higher ultimate tensile load (944 ± 231 vs 784 ± 287 N; P = .03). For the other measures (load at 2 mm of displacement, energy absorbed at failure and at 2 mm of displacement and stiffness), there were no significant differences between tested constructs.

A Bankart repair construct that used 2 double-loaded anchors was either superior to or equal to a repair construct that used 3 single-loaded anchors in all measured outcomes.

Using 2 double-loaded suture anchors for a Bankart repair may limit anchor holes in the glenoid and reduce the risk of postsurgical glenoid fracture while providing a stable repair construct.

The early stages of spondylolysis are extremely difficult to diagnose on plain radiography. Although several studies have examined changes in active spondylolysis on magnetic resonance imaging (MRI), no studies to date have determined the onset frequency of active spondylolysis detectable on MRI but occult on plain radiography. Moreover, the clinical features of active spondylolysis described in the literature do not facilitate the differentiation of this condition from other causes of low back pain.

This study aimed to evaluate the usefulness of MRI in diagnosing active spondylolysis early and in determining the prevalence of active spondylolysis in cases where findings were not detected on plain radiography. In addition, specific clinical features to aid in the early detection of active spondylolysis were evaluated.

Cohort study; Level of evidence, 3.

Patients were 200 consecutive young athletes (144 boys and 56 girls; mean age, 14.1 ± 1.5 y) with low back pain. All patients were examined by plain radiography (188 with negative findings and 12 with unclear findings of spondylolysis) and MRI. Computed tomography (CT) was performed only for patients with high intensity changes of the pedicle observed on MRI. The presence or absence of low back pain was examined during lumbar spine extension and flexion. The Kemp test on the right and left sides and percussion of the vertebral spinous process were also performed.

Ninety-seven (48.5%) patients showed evidence of active spondylolysis on MRI, findings that had been missed by plain radiography. These pars defects were organized into the following categories based on CT findings: nonlysis stage, 52; very early stage, 37; late early stage, 22; progressive stage, 10; and terminal stage, 0. No significant physical examination factors were identified that could assist in the early detection of active spondylolysis.

The MRI results suggest a high rate of active spondylolysis in young athletes with low back pain who test negative for spondylolysis on plain radiography. Magnetic resonance imaging appears to be useful in the early diagnosis of active spondylolysis, especially as we found no significant physical examination factors that could assist in early detection.

Excessive repetitive loads are widely believed to be the cause of overload or overuse injuries. On third-generation artificial turf, impacts have been found to vary with surface and shoe properties. Mechanical devices are considered not representative for measuring impact absorption during athletic movements, and pressure insoles have been shown as inaccurate with regard to magnitude of force.

To compare impact properties between different third-generation artificial turf systems in combination with various cleat configurations in vivo using force plate technology.

Controlled laboratory study.

Twenty-two male soccer players (mean ± SD: age, 23.1 ± 2.8 y; height, 1.81 ± 0.1 m; body mass, 77.5 ± 6.0 kg) performed 10 short sprints, 5 straight with a sudden stop and 5 with a 90° cut, over a force plate covered with artificial turf for each combination of 3 turf systems and 3 cleat configurations.

During stop sprints, peak impact was significantly higher on a recreational-level turf system than professional-level turf systems with and without an underlying shock pad (3.12 body weight [W] vs 3.01 W and 3.02 W, respectively). During cut sprints, peak impact was significantly higher with traditional round cleats than with turf cleats and bladed cleats (2.99 W vs 2.84 W and 2.87 W, respectively).

The results indicate that both an increase in assumed impact-absorbing surface properties and a larger distribution of shorter cleats produced lower impacts during standardized athletic movements. Regardless, none of the shoe-surface combinations yielded peak impacts of an assumed hazardous magnitude.

The study provides information on the extent to which various third-generation artificial turf systems and cleat configurations affect impact force, widely believed to be a causative factor for overload and overuse injuries.

Platelet-rich plasma (PRP) is an autologous blood product used to treat acute and chronic tendon, ligament, and muscle injuries in over 86,000 athletes in the United States annually. The World Anti-Doping Agency (WADA) banned intramuscular PRP injections in competitive athletes in 2010 because of concerns that it may increase performance-enhancing growth factors. The ban on PRP was removed in 2011 because of limited evidence for a systemic ergogenic effect of PRP, but the growth factors within PRP remain prohibited.

To quantify the effect of PRP injection on systemic growth factors with performance-enhancing effects and to identify molecular markers to detect treated athletes.

Descriptive laboratory study.

Six ergogenic growth factors monitored by WADA—human growth hormone (hGH), insulin-like growth factor–1 (IGF-1), insulin-like growth factor binding protein–3 (IGFBP-3), basic fibroblast growth factor (bFGF or FGF-2), vascular endothelial growth factor (VEGF), and platelet-derived growth factor–BB (PDGF-BB)—were measured in 25 patients before (baseline) and at 0.25, 3, 24, 48, 72, and 96 hours after intratendinous leukocyte-rich PRP injection. Eating and exercise were prohibited for 3 hours before testing. Growth factors were quantified by enzyme-linked immunosorbent assay, and the change relative to each patient’s baseline was calculated.

Relative to serum, PRP contained significantly more bFGF (226 vs 5 pg/mL), VEGF (1426 vs 236 pg/mL), and PDGF-BB (26,285 vs 392 pg/mL), but IGF-1 and hGH were not elevated. Serum levels increased significantly for IGF-1 at 24 and 48 hours, for bFGF at 72 and 96 hours, and for VEGF at 3, 24, 48, 72, and 96 hours after PRP injection. Additionally, VEGF was increased in all 25 patients after PRP treatment.

Serum IGF-1, VEGF, and bFGF levels are significantly elevated after PRP injection, supporting a possible ergogenic effect of PRP. An indirect marker for hGH doping, the product of IGFBP-3 × IGF-1, also significantly increased after PRP. Platelet-rich plasma appears to trigger an increase in circulating growth factors through activating biological pathways rather than by serving as a vehicle for the direct delivery of presynthesized growth factors. Elevated VEGF was observed in all patients after PRP, and ≥88% of patients had elevated VEGF at each time point from 3 to 96 hours after PRP, suggesting that VEGF may be a sensitive molecular marker to detect athletes recently treated with PRP.

This is the first and only adequately powered study of the systemic effects of PRP. We present evidence that PRP contains and may trigger systemic increases in substances currently banned in competitive athletes. Finally, we provide evidence that VEGF could serve as a useful molecular marker to detect athletes treated with PRP.

Basic fibroblast growth factor (FGF-2) is a powerful stimulator of fibroblast proliferation and type I/III collagen production.

Overexpression of FGF-2 via direct recombinant adeno-associated virus (rAAV) vector–mediated gene transfer enhances the healing of experimental lesions to the human anterior cruciate ligament (ACL).

Controlled laboratory study.

rAAV vectors carrying a human FGF-2 sequence or the lacZ marker gene were applied to primary human ACL fibroblasts in vitro and to intact or experimentally injured human ACL explants in situ to evaluate the efficacy and duration of transgene expression and the potential effects of FGF-2 treatment upon the proliferative, metabolic, and regenerative activities in these systems.

Sustained, effective dose-dependent lacZ expression was achieved in all systems tested (up to 96% ± 2% in vitro and 80%-85% in situ for at least 30 days). rAAV allowed for continuous FGF-2 production both in vitro and in the intact ACL in situ (32.7 ± 1.4 and 33.1 ± 0.8 pg/mL/24 h, respectively, ie, up to 41-fold more than in the controls at day 30; always P ≤ .001), leading to significantly and durably enhanced levels of proliferation and type I/III collagen production vis-à-vis lacZ (at least 3- and 4-fold increases at day 30, respectively; always P ≤ .001). Most notably, rAAV FGF-2 promoted a significant, long-term production of the factor in experimental ACL lesions (92.7 ± 3.9 pg/mL/24 h, ie, about 5-fold more than in the controls; P ≤ .001) associated with enhanced levels of proliferation and type I/III collagen synthesis (at least 2- and 4-fold increases at day 30, respectively; always P ≤ .001). Remarkably, the FGF-2 treatment allowed for a decrease in the amplitude of such lesions possibly because of the increased expression in contractile α–smooth muscle actin, ligament-specific transcription factor scleraxis, and nuclear factor–κB for proliferation and collagen deposition, which are all markers commonly induced in response to injury.

Efficient, stable FGF-2 expression via rAAV enhances the healing of experimental human ACL lesions by activating key cellular and metabolic processes.

This approach has potential value for the development of novel, effective treatments for ligament reconstruction.

In female athletes, sports-related injuries to the anterior cruciate ligament (ACL) increase during adolescence and peak in incidence during the mid- to late teens. Although biomechanical investigations indicate that a potential window of opportunity exists for optimal timing for the initiation of integrative neuromuscular training (NMT) in young female athletes, the influence of the timing of initiation of these programs on the efficacy of ACL injury reduction has yet to be evaluated.

The purpose of the current report was to systematically review and synthesize the scientific literature regarding the influence of age of NMT implementation on the effectiveness for reduction of ACL injury incidence. The hypothesis tested was that NMT would show a greater effect in younger populations.

Meta-analysis; Level of evidence 1a.

Data were pooled from 14 clinical trials that met the inclusion criteria of (1) number of ACL injuries reported; (2) NMT program used; (3) female participants were included; (4) investigations used prospective, controlled trials; and (5) age of participants was documented or was obtainable upon contact with the authors. A meta-analysis with odds ratio (OR) was used to compare the ratios of ACL injuries between intervention and control groups among differing age categorizations.

A meta-analysis of the 14 included studies demonstrated significantly greater knee injury reduction in female athletes who were categorized in the preventive NMT group compared with those who were in the control group (OR: 0.54; 95% confidence interval [CI]: 0.35, 0.83). Lower ACL injuries in mid-teens (OR 0.28; CI: 0.18, 0.42) compared with late teens (OR 0.48; CI: 0.21, 1.07) and early adults (OR 1.01; CI: 0.62, 1.64) were found in participants undergoing NMT.

The findings of this meta-analysis revealed an age-related association between NMT implementation and reduction of ACL incidence. Both biomechanical and the current epidemiological data indicate that the potential window of opportunity for optimized ACL injury risk reduction may be before the onset of neuromuscular deficits and peak knee injury incidence in female athletes. Specifically, it may be optimal to initiate integrative NMT programs during early adolescence, before the period of altered mechanics that increase injury risk.