The American Journal of Sports Medicine

Background: The choice of different graft types and surgical techniques used when reconstructing a torn anterior cruciate ligament may influence the long-term prevalence of osteoarthritis and functional outcomes.

Hypothesis: There are no differences in the prevalence of knee osteoarthritis or knee function in patients undergoing reconstruction of a torn anterior cruciate ligament with 4-strand hamstring autograft versus patellar tendon—bone autograft.

Study Design: Randomized controlled trial; Level of evidence, 1.

Methods: Seventy-two patients with subacute or chronic rupture of the anterior cruciate ligament were randomly assigned to autograft reconstruction with 4-strand gracilis and semitendinosus tendon (HAM) (N = 37) or with patellar tendon—bone (PTB) (N = 35) from the ipsilateral side. Outcome measurements were the Cincinnati knee score, single-legged hop tests, isokinetic muscle strength tests, pain, knee joint laxity test (KT-1000 arthrometer), and a radiologic evaluation (Kellgren and Lawrence) at 10-year follow-up.

Results: At 10 years, 57 patients (79%) were eligible for evaluation—29 in the HAM group and 28 in the PTB group. No differences were found between the 2 graft groups with respect to the Cincinnati knee score, the single-legged hop tests, pain, muscle strength measurements, or knee joint laxity. Fifty-five percent and 64% of the patients had osteoarthritis corresponding to Kellgren and Lawrence grade 2 or more in the HAM and the PTB groups, respectively (P = .27). For the uninvolved knee, the corresponding numbers were 28% and 22% (P = .62).

Conclusion: At 10 years postoperatively, no statistically significant differences in clinical outcome between the 2 graft types were found. The prevalence of osteoarthritis was significantly higher in the operated leg than in the contralateral leg, but there were no significant differences between the 2 groups. The results indicate that the choice of graft type after an anterior cruciate ligament injury has minimal influence on the prevalence of osteoarthritis 10 years after surgery.

Background: The incidence of osteoarthritis after anterior cruciate ligament reconstruction is disturbingly high, with reports of nearly 50% of patients developing mild to moderate osteoarthritis 6 years after surgery. Few studies have assessed the factors involved in the development of osteoarthritis.

Hypothesis: The following 10 factors will be found to be predictive of osteoarthritis: meniscectomy, chondral damage, patellar tendon grafting, age at surgery, time delay between injury and surgery, type and intensity of postsurgery sport, quadriceps strength, hamstring strength, quadriceps-to-hamstring strength ratio, and residual joint laxity.

Study Design: Cohort study (prognosis); Level of evidence, 1.

Methods: Fifty-six subjects with anterior cruciate ligament reconstruction were followed for 6 years after surgery. Assessment included KT-1000 arthrometer testing, isokinetic strength testing, a return-to-sport questionnaire, and a radiograph assessment. A discriminant analysis was performed to assess which of the 10 factors could discriminate between those patients who developed tibiofemoral and patellofemoral osteoarthritis and those who did not.

Results: Five factors were found to be predictive of tibiofemoral osteoarthritis. Meniscectomy (r = .72) and chondral damage (r = .41) were the strongest discriminators, followed by patellar tendon grafting (r = .37) (χ2 [7, n = 56] = 25.48; P = .001). Weak quadriceps (r = .39) and low quadriceps-to-hamstring strength ratios (r = .6) were very close discriminators (χ2 [8, n = 42] = 15.02; P = .059). For patellofemoral osteoarthritis, meniscectomy (r = .45), chondral damage (r = .75), and age at surgery (r = .65) were predictors or close predictors (χ2 [7, n = 54] = 13.30; P = .065).

Conclusion: As not all 10 factors studied were predictive of osteoarthritis, the hypothesis was only partially proven. Preventing further meniscal and chondral damage in patients with anterior cruciate ligament deficiency is critical. Grafting using the hamstring tendons and restoration of quadriceps-to-hamstring strength balance are associated with less osteoarthritis.

Background: Evidence-based clinical data are required for safe return to play after concussion in sport.

Purpose: The objective of this study was to describe the natural history of concussion in sport and identify clinical features associated with more severe concussive injury, using return-to-sport decisions as a surrogate measure of injury severity.

Study Design: Cohort study (prognosis); Level of evidence, 3.

Methods: Male elite senior, elite junior, and community-based Australian Rules football players had preseason baseline cognitive testing (Digit Symbol Substitution Test, Trail-Making Test—Part B, and CogSport computerized test battery). Players were recruited into the study after a concussive injury sustained while playing football. Concussed players were tested serially until all clinical features of their injury had resolved.

Results: Of 1015 players, 88 concussions were observed in 78 players. Concussion-associated symptoms lasted an average of 48.6 hours (95% confidence interval, 39.5-57.7 hours) with delayed return to sport correlated with ≥4 symptoms, headache lasting ≥60 hours, or self-reported ‘‘fatigue/fogginess.’’ Cognitive deficits using the Digit Symbol Substitution Test and Trail-Making Test—part B recovered concomitantly with symptoms, but computerized test results recovered 2 to 3 days later and remained impaired in 35% of concussed players after symptom resolution.

Conclusion: Delayed return to sport was associated with initially greater symptom load, prolonged headache, or subjective concentration deficits. Cognitive testing recovery varied, taking 2 to 3 days longer for computerized tests, suggesting greater sensitivity to impairment. Therefore, symptom assessment alone may be predictive of but may underestimate time to complete recovery, which may be better estimated with computerized cognitive testing.

Background: Tears of the medial meniscus posterior horn (MMPH) are frequently found in knees with deficient anterior cruciate ligaments (ACLs). There are few studies that have evaluated healing of the menisci and the factors associated with healing.

Hypothesis: The repaired menisci would show good healing in the knees with reconstructed ACLs, and the healing capacity of the menisci would differ according to the size, type, and location of the tear as well as the age and gender.

Study Design: Case series; Level of evidence, 4.

Methods: From August 1997 to February 2007, 311 knees underwent MMPH repair using either a modified all-inside or inside-out technique with concomitant ACL reconstruction. Among these patients, a second-look arthroscopy was performed at a mean of 37.7 months postoperatively (range, 12-128 months) in 140 patients. Clinical parameters and outcomes were evaluated. The repaired menisci were divided into complete, incomplete, and failure-to-heal groups. The factors associated with meniscal healing were statistically assessed.

Results: Among 140 patients, 118 (84.3%) showed complete healing, 17 (12.1%) had incomplete healing, and 5 (3.6%) failed to heal. The clinical success rate was 96.4% (135/140) because patients in the incomplete group showed no clinical symptoms associated with meniscal tears. Healing was associated with the tear location (P < .001) and type of tear (P = .0237) on the univariate analysis and the location (P = .0401) only on the multivariate analysis.

Conclusion: Repaired MMPH tears in knees with reconstructed ACLs healed without complications and had satisfactory clinical results. The tear location and type were factors associated with healing on the univariate analysis and location only on the multivariate analysis.

Background: Increasing the coefficient of friction of the shoe-surface interaction has been shown to lead to increased incidence of anterior cruciate ligament (ACL) injuries, but the causes for this increase are unknown. Previous studies indicate that specific biomechanical measures during landing are associated with an increased risk for ACL injury.

Hypothesis: At foot contact during a sidestep cutting task, subjects use different movement strategies for shoe-surface conditions with a high coefficient of friction (COF) relative to a low friction condition. Specifically, the study tested for significant differences in knee kinematics, external knee moments, and the position of the center of mass for different COFs.

Study Design: Controlled laboratory study.

Methods: Twenty-two healthy subjects (11 male) were evaluated performing a 30° sidestep cutting task on a low friction surface (0.38) and a high friction surface (0.87) at a constant speed. An 8-camera markerless motion capture system combined with 2 force plates was used to measure full-body kinematics, kinetics, and center of mass.

Results: At foot contact, subjects had a lower knee flexion angle (P = .01), lower external knee flexion moment (P < .001), higher external knee valgus moment ( P < .001), and greater medial distance of the center of mass from the support limb (P < .001) on the high friction surface relative to the low friction surface.

Conclusion: The high COF shoe-surface condition was associated with biomechanical conditions that can increase the risk of ACL injury. The higher incidence of ACL injury observed on high friction surfaces could be a result of these biomechanical changes. The differences in the biomechanical variables were the result of an anticipated stimulus due to different surface friction, with other conditions remaining constant.

Clinical Relevance: The risk analysis of ACL injury should consider the biomechanical movement changes that occur for a shoe-surface condition with high friction.

Background: The motion control shoe is a well-developed technology in running shoe design for controlling excessive rearfoot pronation and plantar force distribution. However, there is little information on the leg muscle activation with different shoe conditions.

Hypothesis: The motion control shoe can prevent excessive shank muscle activation and delay fatigue.

Study Design: Controlled laboratory study.

Methods: Twenty female recreational runners with excessive rearfoot pronation were tested with running 10 km on a treadmill on 2 days. Participants wore either a motion control running shoe or neutral running shoe on each day. Activities of their right tibialis anterior and peroneus longus were recorded with surface electromyography. The normalized root-mean-square electromyography and median frequency were compared between the 2 shoe conditions.

Results: Significant positive correlations were found between the root-mean-square eletromyography and running mileage in both the tibialis anterior and peroneus longus in the neutral shoe condition (P < .001). The median frequency dropped in both shoe conditions with mileage, but paired t tests revealed a significantly larger drop in the neutral shoe (P < .001 for peroneus longus, P = .074 for tibialis anterior).

Conclusion: The motion control shoe may facilitate a more stable activation pattern and higher fatigue resistance of the tibialis anterior and peroneus longus in individuals with excessive rearfoot pronation during running.

Clinical Relevance: The motion control shoe may increase the running endurance, thus reduce overuse injuries, in athletes with unstable feet during long-distance running.

Backgound: Hamstring strengthening after anterior cruciate ligament reconstruction is a vital component of the rehabilitation program.

Purpose: The objective of this trial was to investigate the effects of hamstring isokinetic training used in the early phase of the rehabilitation program on the stability, strength, symptoms, and functional outcomes of patients throughout 12 months after anterior cruciate ligament surgery.

Study Design: Randomized controlled clinical trial; Level of evidence, 2.

Methods: Forty-eight men underwent anterior cruciate ligament reconstruction with an ipsilateral bone—patellar tendon—bone autograft. The patients were randomly assigned to perform daily isokinetic hamstring exercises at postoperative 3 weeks (group I) or to perform daily isokinetic hamstring exercises at postoperative 9 weeks (group II). The patients were evaluated monthly for the first 4 months and at the 12th month for postoperative hamstring and quadriceps strength, as well as for knee function via the Cincinnati Knee Rating Scale and International Knee Documentation Committee form.

Results: Hamstring isometric strength at 30° of knee flexion (at the first and second months) and concentric isokinetic strength (at 2, 3, 4, and 12 months) at the angular velocity of 60 deg/s were significantly (P < .05-.01) greater in group I compared with group II. Average scores of the Cincinnati Knee Rating Scale for symptoms were significantly (P < .05-.001) higher in group I compared with group II at all evaluation periods. Walking and stair-climbing scores at 1, 2, 3, and 4 months and squatting score at all evaluation periods were also better (P < .05-.01) in group I compared with group II. In addition, group I exhibited better (P < .01-.001) Lachman test results compared with group II for all postoperative evaluation periods. The International Knee Documentation Committee final rating scores were significantly ( P < .01) greater at 2, 3, and 4 months in group I compared with group II.

Conclusion: The results of this study suggest that hamstring as well as quadriceps strength can be increased via early hamstring strengthening after anterior cruciate ligament reconstruction with no negative impact on knee function.

Background: Press-fit fixation of a tendon graft has been advocated to achieve tendon-to-bone healing.

Hypothesis: Fixation of hamstring tendon grafts with a porous bone scaffold limits bone tunnel enlargement compared with a biodegradable interference screw fixation.

Study Design: Randomized controlled trial; Level of evidence, 1.

Methods: Between 2005 and 2006, 20 patients (17 men, 3 women) with a primary reconstruction of the anterior cruciate ligament (ACL) were enrolled in this study. Patients were randomized to obtain graft fixation in the tibial tunnel either by means of an interference screw (I) or a press-fit fixation with a porous bone cylinder (P). At 3 months after surgery, a computed tomography (CT) scan of the knee was performed, and tunnel enlargement was analyzed in the coronal and sagittal planes for the proximal, middle, and distal thirds of the tunnel. After 6 months and 1 and 2 years, radiographs of the knee in the sagittal and coronal plane were analyzed for bone tunnel widening. The International Knee Documentation Committee (IKDC), Tegner, and Lysholm scores of both groups were compared after 1 and 2 years.

Results: The bone tunnel enlargement determined by CT was 106.9% ± 10.9% for group P and 121.9% ± 9.0% for group I (P < .02) in the anteroposterior (AP) plane and 102.8% ± 15.2% versus 121.5% ± 10.1% in the coronal plane (P < .01). The IKDC, Tegner, and Lysholm scores improved in both groups from preoperatively to postoperatively without significant differences between the 2 groups. There was a trend to higher knee stability in group P after 3 months (0.6 ± 1.4 mm vs 1.8 ± 1.5 mm; P = .08).

Conclusion: Both interference screw and a press-fit fixation lead to a high number of good or very good outcomes after ACL reconstruction. Tibial press-fit fixation decreases the amount of proximal bone tunnel enlargement.

Background: Cartilage tissue engineering using synthetic scaffolds allows maintaining mechanical integrity and withstanding stress loads in the body, as well as providing a temporary substrate to which transplanted cells can adhere.

Purpose: This study evaluates the use of polycaprolactone (PCL) scaffolds for the regeneration of articular cartilage in a rabbit model.

Study Design: Controlled laboratory study.

Methods: Five conditions were tested to attempt cartilage repair. To compare spontaneous healing (from subchondral plate bleeding) and healing due to tissue engineering, the experiment considered the use of osteochondral defects (to allow blood flow into the defect site) alone or filled with bare PCL scaffold and the use of PCL-chondrocytes constructs in chondral defects. For the latter condition, 1 series of PCL scaffolds was seeded in vitro with rabbit chondrocytes for 7 days and the cell/scaffold constructs were transplanted into rabbits’ articular defects, avoiding compromising the subchondral bone. Cell pellets and bare scaffolds were implanted as controls in a chondral defect.

Results: After 3 months with PCL scaffolds or cells/PCL constructs, defects were filled with white cartilaginous tissue; integration into the surrounding native cartilage was much better than control (cell pellet). The engineered constructs showed histologically good integration to the subchondral bone and surrounding cartilage with accumulation of extracellular matrix including type II collagen and glycosaminoglycan. The elastic modulus measured in the zone of the defect with the PCL/cells constructs was very similar to that of native cartilage, while that of the pellet-repaired cartilage was much smaller than native cartilage.

Conclusion: The results are quite promising with respect to the use of PCL scaffolds as aids for the regeneration of articular cartilage using tissue engineering techniques.

Background: Chondrolysis associated with intra-articular administration of local anesthetics has been attributed to chondrocyte death induced by the local anesthetics. The mechanism of how the local anesthetics cause chondrocyte death is not clear.

Purpose: This study was conducted to determine whether and how the local anesthetics cause chondrocyte death.

Study Design: Controlled laboratory study.

Methods: Bovine articular chondrocytes in suspension culture were treated for 1 hour with phosphate-buffered saline or phosphate-buffered saline/medium mixture (as controls); 1% lidocaine alone; 0.25% to 0.5% bupivacaine alone; phosphate-buffered saline with pH values of 4.5, 3.8, 3.4, and 2.4; or mixtures of the local anesthetics and cell culture medium or human synovial fluid. Chondrocyte viability was analyzed by flow cytometry using the LIVE/DEAD Viability/Cytotoxicity Kit.

Results: In 1% lidocaine-alone or 0.25% to 0.5% bupivacaine-alone groups, the rate of cell death was 11.8% to 13.3% of bovine articular chondrocytes, whereas the phosphate-buffered saline control had 8.4% of cell death. Increased chondrocyte death was only found when the pH value of phosphate-buffered saline dropped to ≤3.4. In contrast, when bupivacaine was mixed with cell culture medium, needle-like crystals were formed, which was accompanied with 100% death of chondrocytes. Lidocaine did not form visible crystals when it was mixed with culture medium, but the mixtures caused death of over 96% of chondrocytes (P < .001).

Conclusion: Less than 5% of chondrocyte death was attributable to the anesthetics when applied to the cells alone or in phosphate-buffered saline—diluted solution. Acidity (as low as pH 3.8) or epinephrine in the anesthetic solutions could not account for chondrocyte death. However, chemical incompatibility between the local anesthetics and cell culture medium or human synovial fluid may be the cause of chondrocyte death.

Clinical Relevance: Intra-articular administration of lidocaine and bupivacaine is not an indicated usage of either anesthetic, although such a usage has become a common practice. Physicians should be aware of the potential incompatibility of the drug and synovial fluid.

Background: Men’s intercollegiate lacrosse is played at a fast pace and with significant force. Glove protection is required. However, the thumb is at risk because of contact with opponents’ sticks, the ball, other players, and the ground or artificial surface.

Purpose: To characterize patterns of hand injuries in men’s intercollegiate lacrosse and to compare them with those in similar intercollegiate stick-handling sports that require gloves.

Study Design: Descriptive epidemiology study.

Methods: The National Collegiate Athletic Association (NCAA) Injury Surveillance System was utilized to evaluate thumb injuries in intercollegiate stick-handling sports (men’s lacrosse, women’s lacrosse, and men’s ice hockey) during 16 intercollegiate seasons. Injuries were defined as events requiring an athlete to seek medical treatment and miss competition. Data were collected for injuries to the thumb, phalanges, and hand. Descriptive statistics were performed to calculate rates of injury per 1000 athlete-exposures and the relative exposure of the thumb with respect to total hand injuries. χ2 testing with the Yates correction for continuity was performed to determine differences in proportions of injury among the 3 sports studied.

Results: During 16 intercollegiate seasons, there were 692 thumb, finger, and hand injuries in 3 038 255 athlete-exposures. Total thumb injuries were significantly higher in men’s lacrosse, accounting for 59.4% of total hand injuries, when compared with women’s lacrosse (42%) and men’s ice hockey (35.8%) (P < .001). Thumb fractures and contusions were each also found to be significantly more prevalent ( P < .001) when compared with women’s lacrosse and men’s ice hockey.

Conclusion: Men’s intercollegiate lacrosse requires the use of gloves; nonetheless, injury rates of the thumb are significantly elevated in this sport compared with other gloved, stick-handling sports. Recommendations include the development of gloves with improved thumb protection.

Background: Snowboarding-related injuries have been associated with specific snowboarding skill levels, but differences in specific skill level have not been identified.

Hypothesis: Injury patterns are different among skill levels.

Study Design: Descriptive epidemiology study.

Methods: The subjects were 19 539 snowboarders from the Oku-Mino region in Gifu Prefecture, Japan, who were admitted to our hospital during the 12 snowboarding seasons from 1996 to 2008. They were asked to complete a questionnaire regarding age, gender, self-estimated skill level, injury location, injury type, mechanism of injury, and protective gear. Physicians documented diagnostic variables and injury severity score; these variables were compared among the self-estimated skill levels.

Results: Of the total 19 539 injured snowboarders, 1204 (6.2%) were novices, 6409 (32.8%) were beginners, 9260 (47.4%) were intermediates, 1918 (9.8%) were experts, and the skill level was not known in 748 (3.8%). Proportions of the trunk and multiple injuries increased with increases in skill level; however, the number of head/face injuries decreased with increase in skill level. Upper extremity injuries also decreased with increase in skill level, except in novices. Dislocations and multiple injuries increased with increase in skill level, while lacerations/contusions, fractures, and bruises decreased. The mean overall injury severity score was 3.28 ± 0.02, and the value increased significantly with increase in skill level. The proportion of collision and isolated fall injuries significantly decreased with increase in skill level, but that of jump injuries significantly increased. The percentage of protective gear use increased with the increase in skill level.

Conclusion: Prevalence of injury type, injury location, mechanism of injury, and percentage of protective gear use varied according to skill level, and the severity of the injury increased with increase in skill level. On the basis of our observations, we believe that snowboarding injury prevention strategies should be formulated according to skill level.

Background: Information regarding pelvic fractures sustained during snowboarding is scant.

Purpose: To analyze the epidemiologic data, injury patterns, and types of pelvic fractures sustained during snowboarding. Study Deign: Case series; Level of evidence, 4.

Methods: We analyzed the epidemiologic factors, injury patterns, and types of pelvic fractures in 145 patients with snowboarding-related pelvic fractures who were admitted to our institution from the 1998-1999 to the 2006-2007 ski season.

Results: The incidence of snowboarding-related pelvic fractures was 0.102 per 10 000 ski lift tickets, which amounted to 2% of all snowboarding-related fractures (fifth most common type of fracture among all snowboarding-related fractures). Of the pelvic fractures, 85.5% were stable (type A according to the Tile classification) and 14.5% were unstable (types B and C according to the Tile classification). Isolated sacral fractures had the second-highest incidence (24.1%) after pubic bone and/or ischium fractures (46.9%). A distinct female prevalence was seen (52.4%). Jumps and isolated falls were the main mechanisms of injury (80%), and the incidence of collision was significantly higher in the unstable group than in the stable group (P = .037). In all, 57.9% patients classified their skill level as ‘‘intermediate,’’ and only 9.7% of patients had received professional snowboarding lessons. A total of 30 subjects (20.8%) had other injuries along with pelvic fractures; the patients with multiple injuries were significantly more frequent in the unstable group than in the stable group (P = .035).

Conclusion: Pelvic fractures resulting from snowboarding accidents included a higher proportion with isolated sacral fractures in the stable group and a lower prevalence of associated injuries in the unstable group compared with those resulting from other causes.

Background: The popliteus tendon has important dynamic and static stabilizing functions at the knee. Evaluation of its static role as the ‘‘fifth ligament’’ of the knee and a subsequent analysis of a popliteus tendon reconstruction has not been performed.

Hypothesis: In vitro knee stability can be restored to a popliteus tendon—deficient knee with an anatomic popliteus tendon reconstruction.

Study Design: Controlled laboratory study.

Methods: Eleven nonpaired cadaveric knees were tested under the following popliteus tendon states: intact, sectioned, and reconstructed using an autogenous semitendinosus graft. Each knee was subjected to 10-N·m varus moments, 5-N·m external and internal torques, and 88-N anterior and posterior loads at flexion angles of 0°, 20°, 30°, 60°, and 90°. A 6 degrees of freedom electromagnetic motion tracking system was used to assess motion changes of the tibia with respect to the femur.

Results: Significant increases in external rotation and small but significant increases in internal rotation, varus angulation, and anterior translation motion were found after sectioning the popliteus tendon compared to the intact state. Significant decreases in external rotation were found in the reconstructed state compared with the sectioned state at knee flexion angles of 20°, 30°, 60°, and 90°. Comparing the reconstructed state to the intact state, there were no significant differences at knee flexion angles of 0° and 20°, but significant decreases of external rotation were found at knee flexion angles of 30°, 60°, and 90°. Additionally, there were small but significant differences between the reconstructed and intact state with respect to varus angulation at knee flexion angles of 20°, 30°, and 60°; anterior translation at 20° and 30°; and internal rotation at all flexion angles.

Conclusion: The popliteus tendon has important primary stabilization roles at the knee. The authors also found that an anatomic popliteus tendon reconstruction significantly reduced the increase in external rotation that occurred with sectioning the popliteus tendon; however, differences seen with respect to internal rotation, varus angulation, and anterior translation were not restored.

Clinical Significance: The popliteus tendon functions essentially as the fifth major ligament of the knee. An anatomic popliteus tendon reconstruction can restore external rotation stability to knees with popliteus tendon injury.

Background: Ligament restraints to terminal knee extension are poorly understood.

Hypotheses: (1) As with other motions of the knee, genu recurvatum is limited primarily by a named, identifiable structure. (2) As the largest static structure of the posterior knee, the oblique popliteal ligament is uniquely suited to act as a checkrein to knee hyperextension.

Study Design: Descriptive laboratory study.

Methods: Twenty fresh-frozen human knees were divided into 3 groups for a ligament sectioning study. Extension moments of 14 and 27 N·m were applied before and after sectioning of each ligament, and motion changes were recorded. In group 1, the oblique popliteal ligament was sectioned first, followed by the fabellofibular ligament, ligament of Wrisberg, anterior cruciate ligament, posterolateral structures, and posterior cruciate ligament. In group 2, the order was altered to section the anterior cruciate ligament first; no other changes were made. Similarly, the cutting order for group 3 was altered to section the posterior cruciate ligament first. The sagittal tibial slope of each specimen was documented off a lateral radiograph.

Results: The greatest increase in knee hyperextension was observed after sectioning the oblique popliteal ligament. This was independent of cutting order, consistent across groups, and statistically significant. In all groups, the increase in knee hyperextension after sectioning the oblique popliteal ligament approached or exceeded the increases seen after sectioning the anterior and posterior cruciate ligaments combined. Overall, less knee hyperextension was seen in knees with increased posterior tibial slope.

Conclusion: The oblique popliteal ligament was found to be the primary ligamentous restraint to knee hyperextension.

Clinical Relevance: Further studies are needed to determine if surgical repair or reconstruction of the oblique popliteal ligament can restore normal motion limits in patients with symptomatic genu recurvatum. Patients with decreased posterior tibial slope would have increased recurvatum with posterior structure injury, which increases the likelihood of increased symptoms in this population.

Background: The in situ forces of the anteromedial (AM) and posterolateral bundles (PL) of the anterior cruciate ligament (ACL) under simulated functional loads such as simulated muscle loads have not been reported. These data are instrumental for improvement of the anatomical double-bundle ACL reconstruction.

Hypothesis: The load-sharing patterns of the 2 bundles are complementary under simulated muscle loads.

Study Design: Descriptive laboratory study.

Methods: Eight cadaveric knees in this study were sequentially studied using a robotic testing system. Each knee was tested under 3 external loading conditions including (1) a 134-N anterior tibial load; (2) combined rotational loads of 10 N·m of valgus and 5 N·m internal tibial torques; and (3) a 400-N quadriceps muscle load with the knee at 0°, 15°, 30°, 60°, and 90° of flexion. The in situ forces of the 2 bundles of ACL were determined using the principle of superposition.

Results: Under the anterior tibial load, the PL bundle carried peak loads at full extension and concurrently had significantly lower force than the AM bundle throughout the range of flexion (P < .05). Under the combined rotational loads, the PL bundle contributed to carrying the load between 0° and 30°, although less than the AM bundle. Under simulated muscle loads, both bundles carried loads between 0° and 30°. There was no significant difference between the 2 bundle forces at all flexion angles (P > .05).

Conclusion: Under externally applied loads, in general, the AM bundle carried a greater portion of the load at all flexion angles, whereas the PL bundle only shared the load at low flexion angles. The bundles functioned in a complementary rather than a reciprocal manner to each other.

Clinical Relevance: The data appear to support the concept that both bundles function in a complementary manner. Thus, how to re-create the 2 bundle functions in an ACL reconstruction should be further investigated.

Background: Tears of the rotator cuff are highly prevalent in patients older than 60 years, thereby presenting a population also suffering from osteopenia or osteoporosis. Suture fixation in the bone depends on the holding strength of the anchoring technique, whether a bone tunnel or suture anchor is selected. Because of osteopenic or osteoporotic bone changes, suture anchors in the older patient might pull out, resulting in failure of repair.

Hypothesis: The aim of our study was to analyze the bone quality within the tuberosities of the osteoporotic humeral head using high-resolution quantitative computed tomography (HR-pQCT).

Study Design: Descriptive laboratory study.

Methods: Thirty-six human cadaveric shoulders were analyzed using HR-pQCT. The mean bone volume to total volume (BV/TV) as well as trabecular bone mineral densities (trabBMDs) of the greater tuberosity (GT) and the lesser tuberosity (LT) were determined. Within the GT, 6 volumes of interest (VOIs) within the LT, and 2 VOIs and 1 control volume within the subchondral area beyond the articular surface were set.

Results: Comparing BV/TV of the medial and the lateral row, significantly higher values were found medially (P < .001). The highest BV/TV, 0.030% ± 0.027%, was found in the posteromedial portion of the GT (P < .05). Regarding the analysis of the LT, no difference was found comparing the superior (BV/TV: 0.024% ± 0.022%) and the inferior (BV/TV: 0.019% ± 0.016%) portion. Analyzing trabBMD, equal proportions were found. An inverse correlation with a correlation coefficient of —0.68 was found regarding BV/TV of the posterior portion of the GT and age (P < .05).

Conclusion: Significant regional differences of trabecular microarchitecture were found in our HR-pQCT study. The volume of highest bone quality resulted for the posteromedial aspect of the GT. Moreover, a significant correlation of bone quality within the GT and age was found, while the bone quality within the LT seems to be independent from it.

Clinical Relevance: The shape of the rotator cuff tear largely determines the bony site of tendon reattachment, although the surgeon has distinct options to modify anchor positioning. According to our results, placement of suture anchors in a medialized way at the border to the articular surface might guarantee a better structural bone stock.

Background: Little work has been made regarding the use of radiographic landmarks in fibular collateral ligament reconstruction. Radiographic tools can be of use to the surgeon in posterolateral reconstruction as secondary checks in the setting of tissue and bony attrition.

Hypothesis: Using standardized radiographic imaging, a zone for femoral tunnel placement in lateral collateral ligament (LCL) reconstruction can be identified.

Study Design: Descriptive laboratory study.

Methods: Eight fresh-frozen unmatched knees, free of any osseous or articular pathological changes, were selected for dissection (mean age, 61.3 years). Skin and surrounding soft tissues were left intact. Subsequent dissection was carried out to identify the true origin of the LCL. A radiographic marker was applied. True lateral radiographs of the distal femur (posterior condyles overlapping) were taken. Digital radiographic images were obtained and analyzed.

Results: The Blumensaat line was found to be closely associated with the LCL origin on lateral radiographic imaging. On average, the LCL ligament was found to be 58% (±4.7%) across the width of the condyle and 2.3 mm (±2.3 mm) distal to the Blumensaat line. In all specimens, the anatomical LCL origin was found to have less than 5 mm variance from the mean.

Conclusion: The LCL origin is located within a specific region that is noted to have a small amount of variance. This is of benefit to the clinician in the traumatic and reconstructive setting where the true origin may not be easily identifiable through dissection.

Clinical Relevance: Intraoperative fluoroscopic imaging can be used as an adjunctive tool for femoral tunnel placement during posterolateral corner and LCL reconstruction.

Background: Revision ulnar collateral ligament reconstruction remains a challenging problem. The objective of this study was to biomechanically evaluate an ulnar collateral ligament reconstruction technique using a suspension button fixation technique that can be used even in the case of ulnar cortical bone loss.

Hypothesis: An ulnar suspension fixation technique for ulnar collateral ligament reconstruction can restore elbow kinematics and demonstrate failure strength comparable to that of currently available techniques.

Study Design: Controlled laboratory study.

Methods: Nine pairs of cadaveric elbows were dissected free of soft tissue and potted. After simulating ulnar cortical bone loss, ulnar collateral ligament reconstruction was performed in 1 elbow of each pair using palmaris longus autograft and a 30-mm RetroButton suspended from the far (lateralmost) ulnar cortex. A docking technique was used for humeral fixation of the graft. Elbow valgus angle was quantified using a Microscribe 3DLX digitizer at multiple elbow flexion angles. Valgus angle was measured with the ulnar collateral ligament intact, transected, and reconstructed. In addition, load-to-failure testing was performed in 1 elbow of each pair.

Results: Release of the ulnar collateral ligament caused a significant increase in valgus angle at each flexion angle tested (P < .002). Reconstructed elbows demonstrated no significant differences in valgus angle from the intact elbow at all flexion angles tested. Load-to-failure tests showed that reconstructed elbows had an ultimate torque (10.3 ± 5.7 N·m) significantly less than intact elbows (26.4 ± 10.6 N·m) (P = .001).

Conclusion: Ulnar collateral ligament reconstruction using a suspension button fixation technique reliably restored elbow kinematics to the intact state. Load-to-failure testing demonstrated comparable fixation strength to several historic controls of primary reconstruction techniques despite the simulated ulnar cortical bone loss.

Clinical Relevance: Ulnar collateral ligament reconstruction using a suspension button fixation technique can be considered in the case of ulnar cortical bone loss in a primary or revision setting.

Background: Internal oblique muscle injuries are common in professional baseball pitchers and may require a prolonged convalescence of up to 10 weeks. Most strains can be diagnosed clinically, but imaging can be helpful to assess the severity of injury, which may predict recovery and return to play.

Hypothesis: Ultrasound-guided injection of steroid and local anesthetic into the muscle tear can speed recovery and subsequent return to play.

Study Design: Case series; Level of evidence, 4.

Methods: Three professional baseball pitchers with acute tears of the internal oblique muscle confirmed by magnetic resonance imaging underwent ultrasound-guided injection of steroid and local anesthetic.

Results: All 3 patients experienced significant pain relief within a few days of the injection and were able to pitch at full speed within 3 weeks of injury (mean, 21 days) and return to able status by 5 weeks (mean, 30.7 days). The 3 athletes continue to pitch in Major League Baseball 36 months, 36 months, and 14 months, respectively, after injury, and none have sustained reinjury during this time.

Conclusion: Therapeutic injection of steroids and anesthetic under ultrasound guidance appears to speed recovery and rehabilitation in professional baseball pitchers with acute side strains.

Background: Isokinetic muscle strength testing using the peak torque value is the most frequently included quadriceps muscle strength measurement for anterior cruciate ligament (ACL)—injured subjects.

Purpose and Hypotheses: The purpose of this study was to investigate quadriceps muscle performance during the whole isokinetic curve in subjects with ACL deficiency classified as potential copers or noncopers and to investigate whether these curve profiles were associated with single-legged hop performance. We hypothesized that quadriceps muscle torque at other knee flexion angles than peak torque would give more information about quadriceps muscle strength deficits. Furthermore, we hypothesized that there would be significant torque differences between potential copers and noncopers and a significant relationship between angle-specific torque values and single-legged hop performance.

Study Design: Cross-sectional study; Level of evidence, 3.

Methods: Seventy-six individuals with a complete unilateral ACL rupture within the last 3 months were included. The subjects were classified as potential copers and noncopers. Isokinetic quadriceps muscle tests were performed at 60 deg/s. Mean torque values were calculated for peak torque as well as for specific knee flexion angles. The 1-legged hop and the 6-m timed hop tests were included, and symmetry indices were used.

Results: The peak torque value did not identify the largest quadriceps muscle strength deficit. Rather, these were established at knee flexion angles of less than 40°. There were significant differences in angle-specific torque values between potential copers and noncopers (P < .05). Moderate to strong associations were disclosed between angle-specific torque values and single-legged hop performance, but only for noncopers (r ≥ .32-.58).

Conclusion: Angle-specific quadriceps muscle torque values of less than 40° of knee flexion provide more information on the quadriceps strength deficits after ACL injury than the commonly used peak torque values. Interpretation of the isokinetic curve profiles seems to be of clinical importance for the evaluation of quadriceps muscle performance after ACL injury.

Background: Hill-Sachs lesions are often present with recurrent shoulder instability and may be a cause of failed Bankart repair.

Hypothesis: Glenohumeral joint stability decreases with increasingly larger humeral head defects.

Study Design: Descriptive laboratory study.

Methods: Humeral head defects, 1/8, 3/8, 5/8, and 7/8 of the humeral head radius, were created in 8 human cadaveric shoulders, simulating Hill-Sachs defects. Testing positions included 45° and 90° of abduction and 40° of internal rotation, neutral, and 40° of external rotation. Testing occurred at each defect size sequentially from smallest to largest for all abduction and rotation combinations. The humeral head was translated at 0.5 mm/s 45° anteroinferiorly to the horizontal glenoid axis until dislocation. Distance to dislocation, defined as humeral head translation until it began to subluxate, was the primary outcome measure.

Results: Significant factors by ANOVA were rotation (P < .001) and defect size (P < .001). There was no difference for the 2 abduction angles. External rotation of 40° significantly reduced distance to dislocation compared with neutral and 40° internal rotation (P < .001). Osteotomies of 5/8 and 7/8 radius significantly decreased distance to dislocation over the intact state (P = .009 and P < .001, respectively). Post hoc analysis determined significant differences for the rotational positions. Decreased distance to dislocation occurred at 5/8 radius osteotomy at 40° external rotation with 90° of abduction (P = .008). For the 7/8 radius osteotomy at 90° abduction, there was a decreased distance to dislocation for neutral and 40° external rotation (P < .001); at 45° abduction, there was a decreased distance to dislocation at 40° external rotation (P < .001). With the humerus internally rotated, there was no significant change in distance to dislocation.

Conclusion: Glenohumeral stability decreases at a 5/8 radius defect in external rotation and abduction. At 7/8 radius, there was a further decrease in stability at neutral and external rotation.

Clinical Relevance: Defects of 5/8 the humeral head radius may require treatment to decrease the failure rate of shoulder instability repair.

Background: Tightness of the posteroinferior capsule is assumed to be the cause of internal rotation loss in baseball pitchers. Although the relationship between posterior capsule and subacromial impingement has been recognized, this relationship during the baseball-pitching motion is unclear.

Hypothesis: Contact pressure during baseball-pitching motion increases with posterior capsule tightness.

Study Design: Controlled laboratory study.

Methods: Eight fresh-frozen shoulders were used. The peak contact pressure and area on the coracoacromial arch were measured on a custom-designed shoulder experimental device capable of 6 degrees of freedom motion. Simultaneously, the sites of peak pressure on the coracoacromial arch and humerus were observed from various angles. The posteroinferior capsule tightness was simulated by plicating the capsule in the region from 6 to 8 o’clock. The static testing positions correlated to the early cocking, late cocking, acceleration, deceleration, and follow-through phases of the pitching motion.

Results: The peak contact pressure during the follow-through phase (0.63 ± 0.50 MPa) significantly increased with posteroinferior capsule tightness (1.00 ± 0.65 MPa) (P = .014). Additionally, the contact area on the coracoacromial ligament during the follow-through phase (0.98 ± 0.67 cm2) significantly increased with posteroinferior capsule tightness (1.47 ± 0.91 cm 2) (P < .001). The site of the peak contact pressure did not change between the 2 conditions.

Conclusion: Our findings demonstrate that posteroinferior capsule tightness leads to higher contact pressure under the subacromial arch and increased contact area, particularly on the coracoacromial ligament during the follow-through phase.

Clinical Relevance: This tightness may affect risk of injury of the rotator cuff and its surrounding tissues by increasing subacromial contact during pitching.

Background: To address persisting controversy in the literature concerning the efficacy of arthroscopic compared to open acromioplasty, a meta-analysis was performed to evaluate the treatment effect after both approaches.

Hypothesis: The final clinical outcomes will be the same after both open and arthroscopic acromioplasty. However, the arthroscopic technique results in faster recovery and less postoperative morbidity as reflected by faster return to work and decreased hospital stays.

Study Design: Meta-analysis; Level of evidence, 3.

Methods: We performed our search of published English language literature using PubMed. We also searched the proceedings from 4 major orthopaedic meetings convened from 2000 to 2007. Furthermore, the reference sections of all relevant articles were reviewed for pertinent studies and presentations. Nine studies met the inclusion criteria that directly compared arthroscopic versus open acromioplasty with minimum follow-up of 1 year. The analysis focused on 1-year clinical outcome and included comparison of the objective 100-point score, hospital stay, time until return to work, operative time, and complications.

Results: No significant differences were found in clinical outcomes or complications for the 2 groups. However, open acromioplasty was associated with longer hospital stays (2.3 days, P = .05) and a greater length in time until return to work (65.1 days) compared with the arthroscopic technique (48.6 days) (P < .05).

Conclusion: Arthroscopic and open acromioplasty have equivalent ultimate clinical outcomes, operative times, and low complication rates. However, arthroscopic acromioplasty results in faster return to work and fewer hospital inpatient days compared with the open technique.

Recent studies have reported that massive rotator cuff tears do not heal as predictably as, and may have diminished clinical outcomes compared with, smaller rotator cuff tears. An improved understanding of the biologic degeneration and the biomechanical alterations of massive rotator cuff tears should provide better strategies to optimize outcomes. The approach to patients with massive rotator cuff tears requires careful assessment of the patient and the extent of rotator cuff degeneration to determine the appropriate treatment. For a rotator cuff tear that is repairable, the goal is to produce a tension-free, anatomical repair that restores the footprint using soft tissue releases and various suturing techniques, including double-row, transosseous-equivalent suture bridges or the rip-stop stitch. For irreparable cuff tears, the surgeon may elect to proceed with 1 of 2 approaches: (1) palliative surgical treatment—that is, rotator cuff debridement, synovectomy, biceps tenotomy, tuberoplasty and/or nonanatomical repair with partial repair; or (2) salvage treatment with various tendon transfers. Even though the biomechanical constructs for rotator cuff repairs have been improved, the integrity of the repair still depends on biologic healing at the tendon-to-bone junction. There has been much interest in the development of a scaffold to bridge massive rotator cuff tears and adjuvant biologic modalities including growth factors and tenocyte-seeded scaffolds to augment tendon-to-bone healing. The treatment of rotator cuff disease has improved considerably, but massive rotator cuff tears continue to pose a challenging problem for orthopaedic surgeons.