Abstract
Background:
Concomitant arthroscopic rotator cuff repair (ARCR) and microfracture (MFX) for glenoid articular cartilage lesions among active-duty servicemembers yields lower return-to-duty rates than ARCR alone; however, there is no existing comparison with outcomes after MFX alone to elucidate where these discrepancies arise.
Purpose:
To compare postoperative outcomes and return-to-duty rates after MFX for glenoid cartilage lesions with and without ARCR.
Study Design:
Cohort study; Level of evidence, 3.
Methods:
Active-duty servicemembers 18 to 50 years of age who underwent either simultaneous ARCR/MFX or isolated MFX between January 2010 and August 2021 were eligible for inclusion if they had Outerbridge grade 4 glenoid articular cartilage lesions with or without full-thickness rotator cuff tears. All patients had at least 2 years of follow-up. Patient-reported outcome measures (PROMs), range of motion (ROM), return to duty, adverse events, and reoperations were collected and analyzed.
Results:
Ultimately, 38 patients were eligible for inclusion in the ARCR/MFX cohort and 28 in the MFX cohort, with higher mean age (42.5 vs 35.3 years, P < .0004), higher mean preoperative pain scores (8.2/10 vs 7.1/10, P = .0183), and lower mean preoperative ASES scores (42.9 vs 49.1, P = .0424) among patients with ARCR/MFX. Both cohorts demonstrated significant improvements in pain and PROMs (P < .0001); however, there were no significant differences in final postoperative values between the cohorts. Postoperative ROM was slightly more limited after ARCR/MFX compared with MFX (forward flexion: 154.6° ± 9.9° vs 158.4° ± 4.5°, P = .0300; external rotation: 61.2° ± 8.2° vs 68.0° ± 4.6°, P = .0007; internal rotation: T10.8 ± 2.0 vs T9.5 ± 2.0, P = .0357). There were no significant differences among complications (P = .2076), and rates of return to duty were similar between the cohorts (71.4% for ARCR/MFX, 73.7% for MFX; P = .8389).
Conclusion:
Patients undergoing MFX of glenoid articular cartilage defects with or without concomitant ARCR were found to have significant improvements in pain and PROMs, with very slight limitations in postoperative ROM observed among patients with concomitant ARCR. The results of this study suggest that active-duty military patients undergoing glenoid MFX with ARCR have similar final pain scores, PROMs, complication rates, and return-to-duty rates to patients undergoing MFX alone and can assist in preoperative counseling regarding military career management and postoperative expectations.
Shoulder injuries are common among US active-duty servicemembers, with prevalences as high as 24% reported, and are often attributed to a physically demanding occupation with limited ability to self-regulate activity.1,7,10,14 While the incidence of symptomatic glenohumeral articular cartilage lesions among military patients is not explicitly defined in the existing literature, such cartilage defects are frequently linked to a wide variety of other shoulder pathologies such as instability, rotator cuff tears, and generalized glenohumeral degeneration, pathologies that are common among military patients.3,11,18 Subsequently, understanding treatment for symptomatic glenoid cartilage defects comorbid with more common pathologies like rotator cuff tears is an increasingly relevant topic in treating the young, physically active soldier who is not yet a candidate for shoulder arthroplasty.4,5,12,16,17
Microfracture (MFX) is a well-accepted, joint-preserving treatment for glenohumeral articular cartilage lesions in a young, active patient population that can easily augment other shoulder procedures.2,3,4 -6,18 Additionally, there is a greater amount of evidence investigating the use of MFX for glenohumeral cartilage lesions when compared with other treatment modalities. In their 2018 review, Seidl et al 18 reported MFX to have a grade B recommendation for fair evidence to support its use in practice, while evidence for other existing treatment measures, such as nonoperative management, debridement, osteochondral auto- or allograft transplantation, autologous chondrocyte implantation, and particulate juvenile allograft cartilage implantation, is considered conflicting, of poor quality, or insufficient.
Given that MFX is often performed in combination with other shoulder procedures, recent literature has investigated how the addition of MFX affects overall outcomes.4,5,8 Specific to arthroscopic rotator cuff repair (ARCR), Hill et al 8 reported modest improvements in PROMs among patients undergoing ARCR and MFX for focal glenohumeral arthritis, and Green et al 4 identified similar sustainment of PROM improvements among patients undergoing ARCR/MFX as compared with ARCR alone. However, Green et al 4 also found significantly lower rates of return to active duty among patients undergoing ARCR/MFX versus ARCR alone. Subsequently, the question remains: is the lower rate of return to duty more attributable to the glenoid articular cartilage defect in isolation versus in combination with a rotator cuff tear?
This study aimed to investigate postoperative outcomes and return-to-duty rates after MFX for glenoid articular cartilage defects with and without ARCR to offer further insight into the return-to-duty discrepancy identified in the findings of Green et al. 4 We hypothesized that patients undergoing simultaneous ARCR/MFX would have lower return-to-duty rates than patients undergoing MFX alone.
Methods
Patient Population
This retrospective review involves all active-duty military patients between 18 and 50 years of age who underwent primary operative debridement and MFX of a glenoid articular cartilage defect with or without simultaneous ARCR. Patients were divided into 2 groups: MFX alone or MFX with concomitant ARCR (ARCR/MFX) for full-thickness tears. All surgical procedures were conducted between January 2010 and August 2021, and all patients had at least 2 years of follow-up. Patients with previous ipsilateral shoulder surgery, concomitant capsulolabral repair, osteochondral defects of the humeral head, partial-thickness osteochondral defects classified as Outerbridge grade 1 to 3, and partial-thickness rotator cuff tears were excluded.
In total, 118 active-duty military patients <50 years of age underwent first-time shoulder surgery including debridement and MFX for a glenoid osteochondral defect classified as Outerbridge grade 4. Three patients with superior glenoid defects were excluded. Of the remaining patients, 42 underwent concomitant capsulolabral repair. The remaining 73 were divided into 2 groups: 43 who underwent debridement and MFX alone and 30 who underwent debridement, MFX, and ARCR. After excluding those lost to follow-up and patients with humeral head articular cartilage defects, 38 patients were included in the MFX group and 28 in the ARCR/MFX group (Figure 1).
Patient inclusion flowchart. ADSM, active-duty servicemember; ARCR, arthroscopic rotator cuff repair; MFX, microfracture; OCD, osteochondral defect.
Clinical Evaluation
Before being indicated for operative intervention, patients were required to undergo a minimum of 3 months of dedicated nonoperative treatment including physical therapy, prescriptions for anti-inflammatory medications, and home exercise without satisfactory improvement in symptoms. All patients had a 1.5-T magnetic resonance arthrogram evaluation preoperatively.
Surgical Procedure
All surgeries were performed by the senior author (N.P.), a fellowship-trained shoulder and elbow surgeon. Patients underwent a preoperative interscalene block and, after induction of general anesthesia, were positioned in the modified–beach-chair position using a Spider hydraulic arm holder (Smith & Nephew) after completion of an examination under anesthesia. All patients underwent diagnostic arthroscopy and related interventions (distal clavicle resection, arthroscopic biceps tenotomy or tenodesis, and subacromial space bursectomy) before ARCR and glenoid MFX. Glenoid articular cartilage defects were diagnosed intraoperatively on diagnostic arthroscopy and considered eligible for inclusion if they were confined to the inferior or central glenoid and classified as Outerbridge grade 4. Glenoid osteochondral defects were measured using a graduated probe, with the anterior to posterior distance measured from the posterior portal and the proximal to distal distance measured from the anterior portal. Rotator cuff tears were stratified as small (<1 cm), medium (1-3 cm), large (>3-5 cm), or massive (>5 cm) based on intraoperative measurements.
To complete the glenoid MFX, slight traction was applied to the humeral head to better access the inferior glenohumeral joint. Debridement of the chondral defect was then completed using an arthroscopic shaver, arthroscopic biter, and/or ring curette. The ring curette was then used to establish vertical walls surrounding the defect and debride calcified cartilage without penetration of the subchondral bone. MFX was performed with an MFX awl, taking care to penetrate the subchondral bone approximately 3 to 4 mm in depth with intervals of 3 to 4 mm between targets. MFX success was confirmed with appropriate bone marrow extravasation upon cessation of arthroscopic inflow.
The bursal aspect of the rotator cuff was then evaluated after limited subacromial bursectomy. The greater tuberosity and edge of the affected rotator cuff tendon were then prepared for repair, and a single-row repair was conducted for tears <1 cm and a transosseous equivalent double-row repair for tears >1 cm.
The surgeon maintained standardized techniques throughout the study period without significant changes.
Postoperative Rehabilitation
All patients underwent outpatient surgery and were discharged on the same day as their procedure. Patients were instructed to begin Codman exercises after cessation of analgesia from the interscalene block. All patients attended physical therapy with the same military physical therapy group. Postoperative protocols differed by study arm:
- Isolated glenoid MFX: Patients received a SmartSling (Ossur) for comfort for the first week postoperatively. Patients were encouraged to begin passive range of motion (ROM) immediately with rapid progression to active-assisted and active ROM as tolerated. Light strengthening was permitted at 6 weeks postoperatively, with unrestricted strengthening permitted at 12 weeks postoperatively. Return to unrestricted activity was permitted at 4 months after both clearance by physical therapy and subjective patient-reported readiness to return to duty.
- Simultaneous glenoid ARCR/MFX: Patients were immobilized in neutral rotation in a SmartSling for 6 weeks. Active ROM was initiated at 6 weeks. A gradual strengthening program was started at 12 weeks. Return to unrestricted activity was permitted at 6 months after both clearance by physical therapy and subjective patient-reported readiness to return to duty.
Data Collection
Patient characteristics included age, sex, laterality, dominant upper extremity, and tobacco use, with pertinent data routinely obtained in preoperative clinical visits. Concomitant pathologies were determined from review of operative reports. Glenoid defect size was routinely measured intraoperatively and recorded in operative reports.
Patient-reported outcome measures (PROMs) and ROM in forward flexion, external rotation, and internal rotation were collected preoperatively and postoperatively with a minimum 2-year follow-up as measured by goniometry performed by the lead surgeon (N.P.) or the physician’s assistant. Specific measurement scales included the visual analog scale (VAS) for pain, the American Shoulder and Elbow Surgeons Standardized Shoulder Assessment (ASES), and the Single Assessment Numeric Evaluation (SANE). Return to duty was routinely collected at postoperative follow-up appointments in addition to adverse events and revision procedures. Outcome data for all patients who required revision surgeries were calculated at the last follow-up before revision surgery.
Statistical Analysis
IBM SPSS Statistics Version 25.0 (IBM Corp) was used to conduct statistical analyses. Continuous data are described using mean, standard deviation, range, and 95% confidence interval. An a priori power analysis was not performed given the retrospective nature of the study. Shapiro-Wilk analyses demonstrated nonparametric data distribution among at least 1 variable in each comparison group; subsequently, Wilcoxon signed-rank tests were used to compare paired data and the Mann-Whitney U test was used to compare 2 independent samples. Chi-square and Fisher exact tests were used to compare categorical variables between groups. Linear regression was used to compare correlations between glenoid defect size and final PROM scores. Statistical significance was defined as a P value <.05.
Results
Patient Characteristics and Preoperative State
Patients in the combined ARCR/MFX cohort were a mean of 7 years older than patients in the MFX cohort (42.5 ± 5.7 years vs 35.3 ± 8.9 years; P < .0004). There were no differences observed among patient sex, tobacco use, proportions of patients with combat arms military occupational specialties, dominant shoulder, laterality, or length of follow-up (Table 1). Of patients with rotator cuff tear undergoing ARCR, 7.1% of tears were classified as small (n = 2), 64.3% as medium (n = 18), 17.9% as large (n = 5), and 10.7% as massive (n = 3). The mean follow-up was 83.0 ± 35.6 months among patients in the MFX cohort and 74.1 ± 33.6 months among patients in the ARCR/MFX cohort.
Patient and Preoperative Characteristics a
Data are given as n (%) or mean ± SD. Boldface P values indicate statistical significance. ARCR, arthroscopic rotator cuff repair; ASES, American Shoulder and Elbow Surgeons Standardized Shoulder Assessment; ER, external rotation; FF, forward flexion; IR, internal rotation; MFX, microfracture; MOS, military occupational specialty; PROM, patient-reported outcome measure; ROM, range of motion; SANE, Single Assessment Numeric Evaluation; VAS, visual analog scale.
On average, patients in the ARCR/MFX cohort reported higher preoperative pain scores, lower preoperative ASES scores, and less preoperative external rotation than patients in the MFX cohort. There were no differences between preoperative SANE scores, forward flexion, internal rotation, and glenoid defect size between the 2 cohorts (Table 1).
Patient-Reported Outcome Measures
Patients in both the ARCR/MFX and MFX groups experienced significant improvements in VAS pain, SANE, and ASES scores postoperatively (Table 2). There were no significant differences observed among final postoperative PROM measurements between groups.
Postoperative PROMs and ROM Values a
Data are given as mean ± SD unless otherwise indicated. Boldface P values indicate statistical significance. ARCR, arthroscopic rotator cuff repair; ASES, American Shoulder and Elbow Surgeons Standardized Shoulder Assessment; ER, external rotation; FF, forward flexion; IR, internal rotation; MD, mean difference; MFX, microfracture; postop, postoperative; preop, preoperative; PROM, patient-reported outcome measure; ROM, range of motion; SANE, Single Assessment Numeric Evaluation; VAS, visual analog scale.
In the ARCR/MFX group, glenoid defects ranged from 8 to 400 mm3 in size, while in the MFX group, glenoid defects ranged from 24 to 400 mm3, without significant differences observed between overall sizes (Table 1). Additionally, there were no correlations between VAS pain, SANE, and ASES scores and cumulative area of the glenoid articular cartilage lesions in either the MFX or ARCR/MFX group (MFX: VAS pain score, P = .7398; SANE score, P = .8139; ASES score, P = .6786; ARCR/MFX: VAS pain score, P = .9775; SANE score, P = .0680; ASES score, P = .7509).
Range of Motion
Patients in the MFX cohort demonstrated statistically significant improvements in forward flexion (from 154.0° ± 14.0° to 158.4° ± 4.5°; P = .0244) that clinically are unlikely to be important; otherwise, improvements in postoperative ROM were not observed among patients in either cohort (Table 2). Final postoperative ROM values were noted to be significantly greater among patients in the MFX versus ARCR/MFX cohort for forward flexion, external rotation, and internal rotation; however, despite significant differences in final ROM values for forward flexion, external rotation, and internal rotation, overall differences between postoperative outcomes only ranged from 2.5% to 12%.
Adverse Events
Among patients in the ARCR/MFX cohort, the overall complication rate was 14.3% (n = 4), with 3 patients sustaining retears after ARCR and 1 patient experiencing continued postoperative stiffness. Among patients in the isolated MFX cohort, the overall complication rate was 5.3% (n = 2), with 1 patient requiring revision MFX at 30 months and another at 44 months due to continued pain postoperatively. There were no significant differences among overall complication rates in the 2 cohorts (P = .2076).
Return to Duty
Rates of return to duty were similar between the 2 cohorts and noted at 71.4% for patients undergoing ARCR/MFX (n = 20) and 73.7% for patients undergoing MFX in isolation (n = 28) (P = .8389).
Discussion
As compared with patients undergoing debridement and MFX alone, patients with glenoid articular cartilage defects who underwent concomitant ARCR/MFX were found to be significantly older with significantly worse preoperative VAS pain and ASES scores. Postoperatively, however, both groups sustained significant improvements in pain and PROMs without meaningful differences between postoperative PROMs at final measurements. Despite significantly lower ROM for forward flexion, external rotation, and internal rotation observed among patients in the ARCR group, likely explained by 6 weeks of sling immobilization, there was no significant difference between the 2 groups regarding final pain scores, PROMs, complication rates, or return-to-duty rates.
Focal, symptomatic glenohumeral articular cartilage defects are uncommon and present a challenging pathology to treat. 18 While shoulder arthroplasty may eventually be indicated for definitive treatment of glenohumeral osteoarthritis, Kusnezov et al 12 described military-specific challenges to total shoulder arthroplasty, including how only 41.4% of patients were able to remain on active duty at 2 years postoperatively and 23.1% of patients underwent reoperation for component failure, likely related to the younger age of military patients on average. Additionally, with high rates of glenoid articular cartilage lesions related to other shoulder pathologies such as traumatic injuries and instability among military servicemembers, understanding how addressing multiple concomitant pathologies affects outcomes offers substantial value to surgeons operating on military servicemembers in preoperative counseling and resource/retention planning.4,5,8,17
There is limited existing literature exploring PROMs after surgical management of glenoid articular cartilage defects, especially among military servicemembers. In their case series of 27 patients undergoing simultaneous ARCR/MFX of focal glenohumeral arthritis, Hill et al 8 reported modest improvements in PROMs; however, a majority of the lesions in these patients involved either the humeral head alone or “kissing lesions” of both the humeral head and glenoid, with only 1 case of a glenoid articular cartilage defect in isolation. Furthermore, the mean age of patients in this series was 65 years, which is substantially older than the average military patient indicated for MFX based on the presence of a glenoid articular cartilage lesion rather than glenohumeral arthritis. Specific to military servicemembers, there is evidence that patients undergoing concomitant MFX and glenohumeral stabilization have significantly worse PROMs as compared with patients undergoing stabilization alone, emphasizing the importance of studying how the presence and treatment of glenoid articular cartilage defects with concomitant pathologies can affect overall outcomes. 5 However, among other groups of military servicemembers, multiple studies have noted improvement in PROMs after glenoid MFX, despite overall variations in rates and success.4,5,8,17
This study highlights evidence of significant improvements in PROMs within ARCR/MFX and MFX cohorts, with similar final measures observed between the 2 groups. While postoperative ROM is the most notable discrepancy separating outcomes between the two, with slightly greater improvements observed among patients undergoing isolated MFX, differences in final postoperative ROM measurements are minimal and likely clinically unimportant. One explanation for these mild discrepancies lies in differences between postoperative protocols for the 2 cohorts, with patients in the ARCR cohort confined to a sling for 6 weeks postoperatively. As compared with an accelerated rehabilitation protocol, the use of a postoperative sling exchanges short-term ROM advancements for protection against retears,9,13,15 offering insight into the postoperative stiffness observed among the ARCR/MFX cohort. The absence of ROM limitations among the isolated MFX cohort suggests that these discrepancies are limited to the addition of ARCR, which is an important factor to include in preoperative and postoperative patient counseling. However, the lack of differences in final VAS pain, ASES, and SANE scores and minimal change in final ROM is reassuring in projecting the achievement of satisfactory PROMs and return to duty in this population. A previous study of military servicemembers undergoing isolated ARCR versus combined ARCR and glenoid MFX demonstrated similar forward flexion and internal rotation among both cohorts and greater external rotation among the isolated ARCR cohort 4 ; subsequently, the results of the present study suggest that while ARCR is the rate-limiting step in maximizing postoperative ROM, the addition of MFX may exacerbate this discrepancy given that patients undergoing both procedures sustained globally decreased ROM, especially in external rotation, as compared with patients undergoing MFX alone.
Another key finding of this study lies in the similar rates of return to duty after MFX with and without ARCR. Ultimately, 71.4% of patients in the ARCR/MFX cohort and 73.7% of patients in the MFX cohort were able to return to full, unrestricted duty with no significant differences observed between return-to-duty rates in each group. In the study by Green et al 4 comparing cohorts undergoing ARCR with or without MFX, a significantly greater rate of patients who underwent ARCR without MFX were able to return to full duty (88.3% vs 71.4%; P = .05). Additionally, a separate study by Green et al 5 comparing return to duty in patients undergoing capsulolabral repair for instability with or without MFX found an even more notable discrepancy, with return-to-duty rates of only 58.0% for patients undergoing both stabilization and MFX and 93.8% for patients undergoing stabilization alone. Performed in isolation, retention rates on full active duty after glenoid MFX among soldiers is not much better, at 65% for patients to remain on unrestricted duty, with the remaining 35% indicated for medical discharge. 17 Consequently, in the context of these findings, return to duty appears to be more driven by the presence of glenoid articular cartilage defects than rotator cuff tears and related pathology.
Limitations
There are a number of limitations in this study. First, sample size is limited, given both the rarity of glenoid articular cartilage defects in society overall and the inclusion of results from 1 fellowship-trained shoulder elbow surgeon, which could render results less generalizable. Additionally, with a small sample size, stratification of rotator cuff tear size was not feasible and assessment of tear size on outcomes was not performed. Second, the study population was relatively homogeneous, with the majority of patients found to be male and <50 years of age, which may be less generalizable to a nonmilitary population. Third, cartilage lesions classified as Outerbridge grade 4 encompass a spectrum of pathologies and may reflect an additional variability. Finally, a retrospective assessment of prospectively collected data can introduce selection bias in patient inclusion.
Conclusion
Patients undergoing MFX of glenoid articular cartilage defects with or without concomitant ARCR were found to have significant improvements in pain and PROMs, with very slight limitations in postoperative ROM observed among patients with concomitant ARCR. The results of this study suggest that active-duty military patients undergoing glenoid MFX with ARCR have similar final pain scores, PROMs, complication rates, and return-to-duty rates to patients undergoing MFX alone and can assist in preoperative counseling regarding military career management and postoperative expectations.
Footnotes
Final revision submitted November 11, 2024; accepted December 16, 2024.
One or more of the authors has declared the following potential conflict of interest or source of funding: N.P. has received consulting fees from DePuy Synthes and Medical Device Business Services and hospitality payments from Smith & Nephew. J.P.S. is a committee member for ASES and has received hospitality payments from Stryker and Encore Medical. E.D.C. has received hospitality payments from Arthrex, Rattan and Associates, and Stryker; education payments from Rattan and Associates, Arthrex, Sequoia Surgical, Smith & Nephew, Medical Device Business Services, and Pylant Medical; and a grant from Arthrex. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto.
Ethical approval for this study was waived by Carson-Carthage IRB (No. 2023-08).
