Superior Capsule Reconstruction Using Fascia Lata Allograft Compared With Double- and Single-Layer Dermal Allograft: A Biomechanical Study

Middle trapezius tendon transfer using Achilles allograft for irreparable isolated supraspinatus tendon tears effectively restores the superior stability of the humeral head without restricting range of motion: a biomechanical study

BACKGROUND

Middle trapezius tendon (MTT) transfer has been suggested for promising treatment of irreparable isolated supraspinatus tendon tears (IISTTs). However, there have been no attempts to assess the biomechanical efficacy of MTT transfer. This study aims to evaluate the biomechanical efficacy of MTT transfer in the setting of IISTTs.

METHODS

Eight fresh frozen cadaveric shoulders were tested in 3 conditions: (1) intact rotator cuff, (2) IISTT, and (3) MTT transfer using Achilles allograft for IISTTs. Total humeral rotational range of motion (ROM), superior translation of the humeral head, and subacromial contact characteristics were measured at 0°, 20°, and 40° glenohumeral abduction (representing 0°, 30°, and 60° shoulder abduction). Superior translation and subacromial contact pressures were measured at 0°, 30°, 60°, and 90° external rotation (ER). Two different MTT muscle loading conditions were investigated. A linear mixed effects model and Tukey post hoc test were used for statistical analysis.

RESULTS

Total ROM was significantly increased after IISTT at 20° abduction (P = .037). There were no changes in total ROM following MTT transfer compared to the IISTT condition (P > .625 for all comparisons). The IISTT condition significantly increased superior translation compared to the intact rotator cuff condition in 0° and 20° abduction with all ER angles (P < .001), 40° abduction-30° ER (P = .016), and 40° abduction-60° ER (P = .002). MTT transfer significantly decreased superior translation of the humeral head at all abduction angles compared to the IISTT condition (P < .026). MTT transfer significantly decreased peak contact pressure by 638.7 kPa (normal loading) and 726.8 kPa (double loading) at 0° abduction-30° ER compared to the IISTT condition (P < .001). Mean contact pressure was decreased by 102.8 kPa (normal loading) and 118.0 kPa (double loading) at 0° abduction-30° ER (P < .001) and 101.0 kPa (normal loading) and 99.2 kPa (double loading) at 0° abduction-60° ER (P < .001). MTT transfer at 20° abduction-30° ER with 24 N loading significantly decreased contact pressure by 91.2 kPa (P = .035).

CONCLUSIONS

The MTT transfer biomechanically restored the superior humeral head translation and reduced the subacromial contact pressure in a cadaveric model of IISTT, while not restricting total ROM. These findings suggest that MTT transfer may have potential as a surgical treatment for IISTTs.

Biomechanical Comparison Between Superior Capsular Reconstruction and Lower Trapezius Tendon Transfer in Irreparable Posterosuperior Rotator Cuff Tears

BACKGROUND

Superior capsular reconstruction (SCR) and lower trapezius tendon transfer (LTT) have recently been used to manage irreparable posterosuperior rotator cuff tears (PSRCTs). There has been a paucity of comparative biomechanical considerations between the 2 procedures.

PURPOSE

To compare the glenohumeral stability and biomechanical properties between SCR and LTT in PSRCTs involving the entire infraspinatus tendon region.

STUDY DESIGN

Controlled laboratory study.

METHODS

Eight fresh-frozen cadaveric shoulders were tested at 0°, 20°, and 40° of shoulder abduction. Maximum internal, external, and total humeral range of motion (ROM), superior translation of the humeral head, and subacromial contact characteristics were compared among 4 conditions: (1) intact rotator cuff, (2) PSRCTs involving the entire infraspinatus tendon region, (3) LTT using Achilles allograft (12 N and 24 N of loading), and (4) SCR using fascia lata allograft.

RESULTS

Although a decrease in total ROM was noted in LTT with 12 N compared with the tear condition, LTT with both 12 N and 24 N as well as SCR did not restrict total rotational ROM compared with the intact condition. LTT had decreased total ROM compared with tear condition at 20° of abduction (P = .042), while no significant decrease was confirmed at all abduction angles after SCR. SCR and LTT with 24 N decreased superior translation compared with the PSRCT condition at 0° and 20° of abduction (P < .037) but not significantly at 40° of abduction, whereas LTT with a 24-N load decreased glenohumeral superior translation at all abduction angles (P < .039). Both SCR and LTT decreased subacromial contact pressure compared with the tear condition (P < .014) at all abduction angles. SCR decreased subacromial contact pressure at 0° and 40° of abduction (P = .019 and P = .048, respectively) compared with LTT with 12 N of loading, while there was no difference between SCR and LTT with 24 N of loading in all abduction angles. SCR increased the contact area compared with the PSRCT condition at all abduction angles (P < .023), whereas LTT did not increase the contact area.

CONCLUSION

SCR and LTT decreased glenohumeral superior translation and contact pressure compared with PSRCT conditions. The LTT was superior to SCR in terms of superior translation of the humeral head at a higher shoulder abduction angle, whereas the SCR showed more advantageous subacromial contact characteristics compared with LTT.

CLINICAL RELEVANCE

These biomechanical findings provide insights into these 2 fundamentally different procedures for the treatment of young and active patients with PSRCTs involving the entire infraspinatus tendon region.

Surgical Management of Massive Irreparable Cuff Tears: Superior Capsule Reconstruction and Rotator Cable Reconstruction

PURPOSE OF REVIEW

Massive irreparable rotator cuff tears (MIRCTs) present treatment challenges. Recently, superior capsule reconstruction (SCR) and anterior cable reconstruction have emerged as surgical options, but no single approach is superior. This review provides an overview of SCR and cable reconstruction techniques, including biomechanical studies, clinical outcomes, and surgical considerations.

RECENT FINDINGS

Biomechanical studies show SCR with autografts or allografts improves glenohumeral stability and mechanics. Clinical outcomes of SCR demonstrate improved range of motion, function scores, and pain relief in short-term studies. Anterior cable reconstruction reduces superior humeral head translation and subacromial pressures in biomechanical models. Early clinical studies report improved rotator cuff healing and outcomes for cable reconstruction in specific irreparable tear patterns. SCR and cable reconstruction are viable surgical options for MIRCTs based on early encouraging results. However, higher-level comparative studies with long-term follow-up are still needed. Careful consideration of tear pattern, patient factors, and surgical goals is required to optimize treatment of MIRCTs. Further research is necessary to determine the optimal role for these procedures.

Glenohumeral Superior Translation and Subacromial Contract Pressure Are Both Improved With Superior Capsular Reconstruction: A Systematic Review and Meta-analysis of Biomechanical Investigations

PURPOSE

To review cadaveric studies evaluating the biomechanical outcomes of superior capsular reconstruction (SCR) with different graft types for the treatment of irreparable rotator cuff (RTC) tears.

METHODS

PubMed, Cochrane, and Embase were queried in January 2022 to conduct this meta-analysis using the following key words: "superior capsule reconstruction," "superior capsular reconstruction," and "biomechanics." Articles were included if they reported glenohumeral superior translation or subacromial contact pressure following SCR in cadaveric RTC tears. The review adhered to the Preferred Reporting Items for Systematic Reviews and Meta-analyses criteria. Number of shoulders, graft types, and biomechanical outcomes were recorded and analyzed with forest plots.

RESULTS

Twelve studies (95 shoulders) were included in the statistical analysis. There was a significant reduction in glenohumeral superior translation following SCR compared with RTC tear across 10 studies (79 shoulders) with standardized mean difference (SMD) -2.48 mm; confidence interval (CI) -3.28 mm, -1.69 mm. The SMD between fascia lata graft and RTC tear was -3.84 mm (CI -4.82 mm, -2.86 mm) and between dermal allograft and RTC tear was -2.05 mm (CI -3.10 mm, -1.00 mm). There was a significant reduction in subacromial contact pressure following SCR compared with RTC tear across 5 studies (55 shoulders) with SMD -3.49 MPa (CI -4.54 MPa, -2.44 MPa). The SMD between fascia lata graft and RTC tear was -3.21 MPa (CI -5.08 MPa, -1.34 MPa) and between dermal allograft and RTC tear was -3.89 MPa (CI -5.91 MPa, -1.87 MPa).

CONCLUSIONS

Independent of graft type, biomechanical studies suggest that SCR improves glenohumeral superior translation and subacromial contact pressure in comparison with RTC tear at time zero. There was no definitive evidence identified in this study to suggest a biomechanically superior SCR graft option.

CLINICAL RELEVANCE

Investigating the biomechanical outcomes of several graft types for superior capsular reconstruction will help surgeons better understand the efficacies of different graft types for use in superior capsule reconstruction surgery.

Postoperative Graft Volume Reduction Is Associated With Inferior Clinical Outcomes of Superior Capsule Reconstruction Using an Acellular Dermal Matrix Allograft

PURPOSE

To evaluate whether postoperative graft volume reduction is associated with clinical outcomes after superior capsule reconstruction (SCR) and to identify factors related to graft volume change.

METHODS

Between May 2018 and June 2021, patients who underwent SCR with acellular dermal matrix allograft for irreparable rotator cuff tear with a minimum 1-year follow-up and who had intact graft continuity in postoperative 6-month magnetic resonance imaging were retrospectively reviewed. The lateral half to the medial half of the graft volume ratio was defined as lateral half graft volume ratio. The difference between the preoperative and postoperative lateral half graft volume ratio was defined as lateral half graft volume change. Patients were divided into 2 groups: those with preserved graft volume (group I) and those with reduced graft volume (group II). Intergroup differences in clinical and radiological characteristics were analyzed.

RESULTS

A total of 81 patients were included, with 47 (58.0%) in group I and 34 (42.0%) in group II. Group I showed significantly lower lateral half graft volume change (0.018 ± 0.064 vs 0.370 ± 0.177; P < .001) than group II. Group II showed significantly greater preoperative Hamada grade (1.3 ± 0.5 vs 2.2 ± 0.6, P < .001), an anteroposterior distance of the graft at the greater tuberosity (APGT) (30.3 ± 4.8 vs 35.2 ± 3.8, P < .001), and fatty infiltration of infraspinatus (2.3 ± 0.9 vs 3.1 ± 0.8, P < .001) and subscapularis (0.9 ± 0.9 vs 1.6 ± 1.3, P = .009) than group I. Group II had a significantly lower proportion of patients achieving MIC in Constant score than group I (70.2% vs 47.1%, P = .035). The Hamada grade, APGT, and fatty infiltration of infraspinatus and subscapularis were independent factors of graft volume change.

CONCLUSIONS

Although SCR improved pain and shoulder function, postoperative graft volume reduction was related to a lower rate of minimal important change achievement in the Constant score compared with preserved graft volume. The preoperative Hamada grade, APGT, and fatty infiltration of infraspinatus and subscapularis were associated with graft volume reduction.

LEVEL OF EVIDENCE

Level III, retrospective case-control study.

Midterm outcome of superior capsular reconstruction using doubled acellular human dermal allograft for irreparable rotator cuff tear

BACKGROUND

Thicker (folded) facia lata autografts have been shown to be superior to thinner grafts and single-layered acellular human dermal (HD) allografts for superior capsular reconstruction (SCR) in biomechanical studies. The aim of this study was to evaluate the midterm clinical outcomes following SCR for irreparable supraspinatus tears using doubled (folded) HD allograft.

METHODS

Thirty-two patients who had undergone SCR using doubled HD allograft between February 2012 and January 2020 were recruited in a continuous manner in this retrospective study. The inclusion criteria were SCR performed for irreparable supraspinatus tear and a minimum of 2 years' follow-up. The primary outcome measure was the American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES) score. The secondary outcome measures were complications and revision surgery. A subgroup analysis was performed between patients who received a "standard" graft of mean 3-mm thickness or a "thick" graft of mean 4.4-mm thickness.

RESULTS

One patient was lost to follow-up. A total of 31 patients (31 shoulder joints) were analyzed with a mean follow-up duration of 48 months (range, 25-96 months). Following surgery, there was significant improvement in the ASES score from 18.1 ± 14.3 (preoperative) to 76.3 ± 25.1 (postoperative) (P < .001), with a satisfactory clinical outcome obtained in 83.8% of the patients. In a subset of 8 patients completing 5 years' follow-up, the clinical improvements were sustained. The percentage of patients with a clinically successful outcome was higher among those with thick grafts compared to those with standard grafts, although this failed to reach statistical significance (94.4% vs. 69.2%, risk ratio 1.36, 95% confidence interval 0.93-1.99, P = .13). One patient within the standard group underwent revision surgery.

CONCLUSION

SCR for irreparable rotator cuff tears with doubled HD allograft results in improved clinical outcomes and low reoperation at midterm follow-up duration.

Superior capsular reconstruction for irreparable rotator cuff tear: a review of current methods

Irreparable massive rotator cuff tears can significantly impact daily life; and these types of tears can be difficult to repair completely, especially in younger patients who are more active and have higher functional requirements. Since its introduction by Mihata and the colleagues, superior capsular reconstruction (SCR) has gained popularity in the treatment of irreparable massive rotator cuff tears and has shown promising short-term results. A variety of studies have focused on the clinical and biomechanical outcomes of this procedure. This article reviews the biomechanics, indications for the surgical procedure, graft options, surgical technique, and rehabilitation from SCR.

Anterior capsular reconstruction in irreparable subscapularis tear: human dermal allograft

BACKGROUND

The irreparable subscapularis (SSc) tears pose an extremely difficult situation to manage, especially in the younger population. The anterior capsular reconstruction (ACR) with human dermal allograft (HDA) is an alternative to tendon transfer with sound biomechanical advantages and clinical outcomes. The purpose of this study was to evaluate the early clinical and radiologic outcomes of open ACR with HDA in patients with irreparable SSc tears.

METHODS

Eighteen patients who had an open ACR with HDA for irreparable SSc tears between August 2020 and January 2022 were enrolled. There were 11 male and 7 female patients with a mean age of 63.7 years and a mean follow-up of 17 months (range, 12-28 months). The dominant side was affected in 10 patients. One of the 18 patients had reconstruction with single-layer HDA, 14 had double-layer HDA, and 3 had SSc augmentation over double-layer HDA. Clinical and radiologic outcomes were assessed and compared pre- and postoperatively.

RESULTS

There was significant improvement in visual analog scale score from 6.6 ± 1.6 to 1.6 ± 1.5 (P < .001) and in the total University of California-Los Angeles shoulder score from 12.4 ± 4.3 to 29.0 ± 4.5 (P < .001). Forward flexion, abduction, and internal rotation (IR) increased by 28.6°, 32.5°, and 11.8°, respectively (P < .001). External rotation decreased by 6.4° (P = .020). There was notable improvement in IR strength (percentage of that of the opposite, normal side) from 66.0% ± 19.4% to 84.4% ± 22.3% (P = .008). The mean postoperative coracohumeral distance improved from 3.0 to 6.0 mm (P < .001), the anterior translation of the humeral head reduced from 1.5 to 0.5 mm (P = .210), and the acromiohumeral interval from 8.1 to 8.8 mm (P = .070). The patients' satisfaction at final follow-up was rated 4.1 of 5.0 (P < .001). Sixteen of 18 patients (88.9%) had the HDA healed at the glenoid and humeral side, and 2 (11.1%) had retear at the final follow-up. Among the 17 who had double-layer HDA, none showed any healing between the layers.

CONCLUSION

This study showed that early significant and comprehensive improvement inclusive of pain relief, improvement in range of motion, IR strength, and reduction of anterosuperior translation was achievable by open ACR with HDA for irreparable SSc tear.

Reliability of a Novel Preoperative Protocol for Determining Graft Sizes for Superior Capsular Reconstruction Using Plain Film Radiography

BACKGROUND

Superior capsular reconstruction (SCR) for massive, irreparable rotator cuff tears involves anchoring a graft between the superior glenoid and the greater tuberosity of the humerus. Optimizing the graft size is important. We aimed (1) to evaluate the reliability of plain film radiography in determining graft size for SCR and (2) to create a database to help predict future graft sizes.

METHODS

An inter- and intra-rater reliability trial was conducted on 10 and 6 subjects with healthy shoulders, respectively, using plain film radiography to measure the distance between the superior glenoid and the supraspinatus footprint. The subjects were positioned upright with an abduction pillow modified to hold the shoulder at 30° abduction and 45° external rotation, afterwhich a true antero-posterior shoulder radiograph was captured. Thirty subjects were recruited for the database and grouped using the aforementioned protocol.

RESULTS

The inter-rater and intra-rater trial agreement was excellent, with intraclass correlation coefficients of 0.94 (95% CI) and 0.76 (95% CI), respectively. Three medio-lateral patch sizes, of 33 mm, 38 mm, and 47 mm, were proposed based on the protocol in 30 subjects.

CONCLUSIONS

Plain film radiography demonstrated excellent reliability in measuring the distance between the superior glenoid and the supraspinatus footprint. Three ordinal patch sizes are proposed.

Superior Capsular Reconstruction Partially Restores Native Glenohumeral Joint Loads In A Dynamic Biomechanical Shoulder Model

PURPOSE

To evaluate the effect of an irreparable posterosuperior rotator cuff tear (PSRCT) on glenohumeral joint loads and to quantify improvement following superior capsular reconstruction (SCR) using an acellular dermal allograft.

METHODS

Ten fresh-frozen cadaveric shoulders were tested using a validated dynamic shoulder simulator. A pressure mapping sensor was placed between the humeral head and glenoid surface. Each specimen underwent the following conditions: (1) native, (2) irreparable PSRCT, (3) SCR using a 3mm-thick acellular dermal allograft. Glenohumeral abduction angle (gAA) and superior humeral head migration (SM) were measured using 3D motion tracking software. Cumulative deltoid force (cDF) and glenohumeral contact mechanics, including contact area (gCA) and contact pressure (gCP), were assessed at rest,15°,30°,45°, and maximum angle of glenohumeral abduction.

RESULTS

The PSRCT resulted in a significant decrease of gAA along with an increase in SM, cDF, and gCP (P<.001, respectively). SCR did not restore native gAA (P<.001), however, SM was significantly reduced (P<.001). Further, SCR significantly reduced deltoid forces at 30° (P=.007) and 45° of abduction (P=.007) when compared to the PSRCT. SCR did not restore native cDF at 30°(P=.015), 45°(P<.001), and maximum angle (P<.001) of glenohumeral abduction. Compared to the PSRCT, SCR resulted in a significant decrease of gCP at 15°(P=.008), 30°(P=.002), and 45°(P=.006). However, SCR did not completely restore native gCP at 45° (P=.038) and maximum abduction angle (P=.014).

CONCLUSION

In this dynamic shoulder model, SCR only partially restored native glenohumeral joint loads. However, SCR significantly decreased glenohumeral contact pressure, cumulative deltoid forces, and superior migration, while increasing abduction motion, when compared to the posterosuperior rotator cuff tear.

CLINICAL RELEVANCE

These observations raise concerns regarding the true joint preserving potential of SCR for an irreparable posterosuperior rotator cuff tear, along with its ability to delay progression of cuff tear arthropathy and eventual conversion to reverse shoulder arthroplasty.

Biomechanical Comparison of Synthetic Polytetrafluoroethylene (PTFE) vs Human Dermal Allograft (HDA), 2 vs 3 Glenoid Anchors, and Suture vs Minitape in Superior Capsule Reconstruction

Background: Superior capsule reconstruction (SCR) is an option for the treatment of massive, irreparable rotator cuff tears. However, which materials yield the strongest constructs remains undetermined. Purposes: We sought to investigate whether SCR with polytetrafluoroethylene (PTFE) or human dermal allograft (HDA), 2 or 3 glenoid anchors, and suture or minitape resulted in better failure load properties at the patch-glenoid interface. Methods: We conducted a biomechanical study in 30 glenoid-sided SCR repairs in Sawbones models divided into 5 groups. Each was pulled to failure to assess mode of failure, peak load (N), stiffness (N/mm), yield load (N), peak energy (N m), and ultimate energy (N m). The 5 groups were as follows: group 1-PTFE, 2 anchors, and suture; group 2-PTFE, 2 anchors, and minitape; group 3-HDA, 2 anchors, and suture; group 4-HDA, 2 anchors, and minitape; group 5-PTFE, 3 anchors, and minitape. Results: Repairs failed by button-holing of suture/minitape. Group 5 had greater peak load, stiffness, yield load, and peak energy (384 ± 62 N; 24 ± 3 N/mm; 343 ± 42 N; 4 ± 2 N m) than group 3 (226 ± 67 N; 16 ± 4 N/mm; 194 ± 74 N; 2 ± 1 N m) or group 4 (274 ± 62 N; 17 ± 4 N/mm; 244 ± 50 N; 2 ± 1 N m) and greater ultimate energy (8 ± 3 N m) than all other groups. Conclusions: This biomechanical study of SCR repairs in Sawbones models found that yield load was greater in PTFE than HDA, 3 anchors were better than 2, and minitape was no better than suture.

Arthroscopic Superior Capsular Reconstruction with Tensor Fascia Lata Allograft for Irreparable Rotator Cuff Tears: Clinical and Radiologic Outcomes for a Minimum 1-Year Follow-Up

PURPOSE

To confirm the radiologic and clinical outcomes after performing arthroscopic superior capsular reconstruction (ASCR) using a tensor fascia lata (TFL) allograft.

METHODS

Thirty-three patients with irreparable rotator cuff tears were treated with ASCR with a TFL allograft. The mean age and follow-up period were 62 years and 20.1 months, respectively. TFL allografts were used as 3, 4, and 6 layers, and the graft thickness was 3.7, 3.9, and 5.4 mm, respectively. Range of motion, visual analog scale (VAS) pain score, American Shoulder and Elbow Surgeons score, and Constant score were evaluated preoperatively and at the final follow-up. The pre-, postoperative, and final acromiohumeral distances (AHD) were compared. The graft integrity was checked through a follow-up magnetic resonance imaging at least 6 months after surgery.

RESULTS

Torn grafts were identified in 6 cases (19%). AHD significantly increased from 5.0 to 8.0 mm postoperatively (P < .0001). However, there was no significant difference of 5.0 mm at the final follow-up AHD. Five cases (83%) of torn grafts were induced in the 3-layered graft sheet group, but the difference was not statistically significant (P = .067). Visual analog scale, forward elevation, internal rotation, American Shoulder and Elbow Surgeons, and Constant scores significantly improved at the last follow-up. Two cases of early infection were confirmed and the graft materials were all removed.

CONCLUSIONS

Despite the possibility of early infection, ASCR using TFL allograft is a reliable procedure for the irreparable rotator cuff tear. In particular, if the number of layers of TFL allograft increases, it is judged that it could become a more effective graft.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Biomechanical outcomes of superior capsular reconstruction for irreparable rotator cuff tears by different graft materials-a systematic review and meta-analysis

Background

Irreparable rotator cuff tears (IRCT) are defined as defects that cannot be repaired due to tendon retraction, fat infiltration, or muscle atrophy. One surgical remedy for IRCT is superior capsular reconstruction (SCR), which fixes graft materials between the larger tuberosity and the superior glenoid.

Patients and methods

The Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) criteria were followed for conducting the systematic review and meta-analysis. From their inception until February 25, 2022, Pubmed, Embase, and Cochrane Library's electronic databases were searched. Studies using cadavers on SCR for IRCT were also included. The humeral head's superior translation and subacromial peak contact pressure were the primary outcomes. The humeral head's anteroposterior translation, the kind of graft material used, its size, and the deltoid load were the secondary outcomes.

Results

After eliminating duplicates from the search results, 1,443 unique articles remained, and 20 papers were finally included in the quantitative research. In 14 investigations, the enhanced superior translation of the humeral head was documented in IRCTs. In 13 studies, a considerable improvement following SCR was found, especially when using fascia lata (FL), which could achieve more translation restraints than human dermal allograft (HDA) and long head of bicep tendon (LHBT). Six investigations reported a subacromial peak contact pressure increase in IRCTs, which could be rectified by SCR, and these studies found a substantial increase in this pressure. The results of the reduction in subacromial peak contact pressure remained consistent regardless of the graft material utilized for SCR. While there was a statistically significant difference in the change of graft material length between FL and HDA, the change in graft material thickness between FL and HDA was not significant. The humeral head's anterior-posterior translation was rising in IRCTs and could be returned to its original state with SCR. In five investigations, IRCTs caused a significant increase in deltoid force. Furthermore, only one study showed that SCR significantly decreased deltoid force.

Conclusion

With IRCT, SCR might significantly decrease the glenohumeral joint's superior and anterior-posterior stability. Despite the risks for donor-site morbidity and the longer recovery time, FL is still the best current option for SCR.

Superior Capsule Reconstruction With Fascia Lata Allograft Has Initial Stiffness and Ultimate Load Comparable to the Native Shoulder Superior Capsule: A Cadaveric Biomechanical Study

PURPOSE

The purpose of this study was to compare the biomechanical characteristics of a fascia lata superior capsule reconstruction (FL-SCR) to the native superior capsule.

METHODS

The native superior capsule of 8 cadaveric shoulders was tested with cyclic loading from 10 to 50 N for 30 cycles in 20° of glenohumeral abduction followed by load to failure at 60 mm/min. Following native superior capsule testing, FL-SCR was performed, which was tested as described for the native capsule. Paired t test was used for statistical analyses with P < .05 for significance.

RESULTS

The stiffness for cycle 1 to 50 N was significantly higher for the native superior capsule compared to the FL-SCR (P = .001). By cycle 30, the stiffness between the two was not statistically different (P = .734). During load to failure, the initial stiffness to 2 mm for the FL-SCR and the native superior capsule was not statistically different (P = .262). The linear stiffness and yield load of the native superior capsule were significantly greater than that of the FL-SCR (94.5 vs 28.0 N/mm, P = .013; 386.9 vs 123.8 N, P = .029). There was no significant difference in ultimate load between the native superior capsule and the FL-SCR (444.9 vs 369.0 N, P = .413).

CONCLUSIONS

FL-SCR has initial stiffness and ultimate load similar to the native superior capsule.

CLINICAL RELEVANCE

The biomechanical properties of FL allograft make it an appealing option as a graft choice for superior capsule reconstruction.

Graft Healing Is More Important Than Graft Technique: Superior Capsular Reconstruction Versus Bridging Grafts-A Prospective Randomized Controlled Trial

PURPOSE

To compare superior capsular reconstruction (SCR) versus bridging graft (BG) for massive irreparable rotator cuff tears (RCTs).

METHODS

A prospective double-blind randomized study was conducted to compare SCR versus BG for massive irreparable RCTs. Fifty patients (mean age: 60.2 ± 6.0 years) with chronic tears (mean duration of symptoms: 5 ± 5.2 years) were intraoperatively randomized following partial repair to SCR or BG using human dermal allograft. All patients underwent standardized rehabilitation and were followed at 3, 6, 12, and 24 months clinically and radiographically. Magnetic resonance imaging were obtained at 12 months to determine graft integrity.

RESULTS

At 2 years, 46 patients were available for follow-up. Mean American Shoulder and Elbow Surgeons (ASES), Western Ontario Rotator Cuff (WORC), and Quick Disabilities of the Arm, Shoulder and Hand scores were 74.8 ± 23.9, 66.0 ± 28.3, and 24.7 ± 26.1 for the SCR group, and 77.9 ± 19.9, 69.5 ± 24.5, and 25.0 ± 19.1 for the BG group, respectively, with no significant difference between groups. Magnetic resonance imaging demonstrated 18 of 24 (75%) in the SCR group and 14 of 22 (64%) in the BG group were intact at 12 months (P = .53). Patients with intact grafts compared with those with retorn grafts, whether SCR or BG, had greater ASES and WORC scores at 24 months (ASES 81.0 ± 18.7 vs 65.7 ± 24.4, P = .021 and WORC 72.3 ± 24.6 vs 53.7 ± 26.7, P = .04) and greater acromiohumeral intervals on radiographs at all follow-up time points.

CONCLUSIONS

When performing arthroscopic reconstruction using human dermal allograft for an irreparable RCT, whether the proximal edge of the graft is attached on the glenoid bone or to the torn tendon does not significantly change short-term clinical and radiographic outcomes.

LEVEL OF EVIDENCE

I, therapeutic.

Revascularization character of autologous fascia lata graft following shoulder superior capsule reconstruction by enhanced magnetic resonance imaging

Background

Fascia lata has been used for arthroscopic superior capsule reconstruction (ASCR) and verified to achieve a good clinical outcome. However, it is still not known about revascularization character of the fascia lata after ASCR. This study was performed to evaluate the revascularization of autologous fascia lata grafts after ASCR by enhanced magnetic resonance imaging (MRI).

Methods

A prospective study of 19 patients with irreparable rotator cuff tears underwent ASCR with autologous fascia lata grafts from September 2019 to April 2021. Radiography examinations and clinical evaluations were performed preoperatively and postoperatively at 6 weeks and 3, 6, and 12 months. The signal-to-noise quotient (SNQ) value and enhancement index (EI) of autologous fascia lata grafts in the great tubercle insertion (GTI), midpoint of the graft (MG), and glenoid insertion (GI) were compared for radiography examination. Clinical evaluation included the American Shoulder and Elbow Surgeons (ASES) score, University of California Los Angeles (UCLA) shoulder score, and Visual Analog Scale (VAS) score.

Results

The SNQ values in T1WI enhancement at GI and GTI were significantly higher than those at the plain MRI scan at all postoperative observation timepoints; however, the SNQ values in T1WI enhancement at MG did not show a significant difference until 3 months postoperation. EI values at GTI and GI were significantly higher than those at MG at 6 weeks and 3 months postoperation, while there was no significant difference in the EI value between GTI and GI. At 6 months postoperation, the EI value at GI was significantly higher than those at MG. At 12 months postoperation, the EI value at GI was significantly higher than those at MG and GTI; however, there was no significant difference between GTI and MG. The EI values at GTI and MG peaked at 3 months and 6 months postoperation, respectively, and then plateaued at 12 months postoperation. However, there was no significant difference in the EI value among the different postoperative timepoints at GI. The EI value did not correlate with the VAS and ASES, UCLA scores at any time point or any postoperative observation location.

Conclusion

Revascularization of the fascia lata was dependent on the location of the fascia lata and plateaus at 12 months postoperation. The EI value did not correlate with the VAS and ASES, UCLA scores during12 months postoperation.

Decellularized Bovine Pericardial Patch Loaded With Mesenchymal Stromal Cells Enhance the Mechanical Strength and Biological Healing of Large-to-Massive Rotator Cuff Tear in a Rat Model

PURPOSE

The purpose of this study was to determine whether the addition of decellularized bovine pericardial patch loaded with mesenchymal stromal cells enhanced bone-to-tendon healing and improved the biomechanical strength of large-to-massive rotator cuff tears in a small animal model.

METHODS

Adipose-derived mesenchymal stromal cells (MSCs) from rat inguinal fat were isolated, cultured, and loaded onto decellularized bovine pericardium patches. To simulate large-to-massive tears, rats were managed with free cage activity for 6 weeks after tear creation. A total of 18 rats were randomly allocated to repair-only (control), repair with pericardial patch augmentation (patch), or repair with MSC loaded pericardial patch augmentation (patch-MSC). Each group had 6 rats (one shoulder of each rat was used for histological evaluation and another for biomechanical evaluation). MSCs seeded on the pericardial patches were traced on four shoulders from 2 other rats at 4 weeks after surgery. Histological evaluation for bone-to-tendon healing and biomechanical testing was carried out at 8 weeks after repair.

RESULTS

MSCs tagged with a green fluorescent protein were observed in the repair site 4 weeks after the repair. One shoulder each in the control and patch groups showed complete discontinuity between the bone and tendon. One shoulder in the control group showed attenuation with only a tenuous connection. Fibrocartilage and tidemark formation at the bone-to-tendon interface (P = .002) and collagen fiber density (P = .040) and orientation (P = .003) were better in the patch-MSC group than in the control or patch group. Load-to-failure in the patch-MSC and patch groups was higher than that in the control group (P = .001 and .009, respectively).

CONCLUSION

Decellularized bovine pericardial patches loaded with adipose-derived and cultured mesenchymal stromal cells enhanced healing in terms of both histology and mechanical strength at 8 weeks following rotator cuff repair in a rat model.

CLINICAL RELEVANCE

Large-to-massive rotator tears need a strategy to prevent retear and enhance healing. The addition of decellularized bovine pericardial patch loaded with MSCs can enhance bone-to-tendon healing and improve biomechanical healing of large-to-massive rotator cuff tears following repair.

Early Treatment of Shoulder Pathology Is Necessary but Not Enough Is Being Performed

Delayed treatment of shoulder instability results in bone loss requiring more-complicated surgery, in turn resulting in less-optimal outcomes. Similarly, delayed treatment of repairable rotator cuff tears results in irreparable tears requiring more-complicated surgery and resulting in less-optimal outcomes. Delayed treatment of shoulder pathology is a problem. Solutions include education and research investigation.

Relationship between the progression of posterosuperior rotator cuff tear size and shoulder abduction function: A cadaveric study via dynamic shoulder simulator

Posterosuperior rotator cuff tear (PSRCT) is one of the most common shoulder disorders in elderly people’s daily life; however, the biomechanical relationship between PSRCT and shoulder abduction function is still controversial. In this study, a total of twelve freshly frozen cadaveric shoulders were included and tested in five conditions: intact rotator cuff, 1/3 PSRCT, 2/3 PSRCT, entire PSRCT, and global RCT. In each condition, extra load (0%, 45%, and 90% failure load) was sequentially added to the distal humerus, and the function of the remaining rotator cuff was mainly evaluated via the middle deltoid force (MDF) required for abduction. It is found that the peak MDF is required for abduction did not differ among the three PSRCT conditions (1/3 PSRCT: 29.30 ± 5.03 N, p = 0.96; 2/3 PSRCT: 29.13 ± 9.09 N, p = 0.98; entire PSRCT: 28.85 ± 7.12 N, p = 0.90) and the intact condition (29.18 ± 4.99 N). However, the peak MDF significantly differed between the global RCT (76.27 ± 4.94 N, p < 0.01) and all PSRCT and intact conditions. Under 45% failure load, the MDF of the entire PSRCT and global tear conditions were significantly increased compared with another status. With the 90% failure load, only the 1/3 PSRCT condition maintained the same shoulder function as the intact rotator cuff. These biomechanical testing jointly suggested that the weight-bearing ability of the shoulder significantly decreased as PSRCT progressed.

Editorial Commentary: Increased Graft Thickness With Superior Capsular Reconstruction Results in Improved Acromiohumeral Distance, but Increased Graft Tear Rate and Lateral Acromial Erosion

For the treatment of irreparable posterosuperior rotator cuff tears of the supraspinatus and infraspinatus, superior capsular reconstruction (SCR) has continued to supplant other less successful and/or reproducible techniques, including partial rotator cuff repair and latissimus tendon transfer. After its initial description utilizing a folded fascia lata autograft with a thickness of up to 8 mm, many in North America adapted their surgical technique to use commercially available human dermal allograft to mitigate donor site morbidity. Early series have revealed the importance of graft thickness in predicting risk of radiographic or clinical failure. As a result, there has been a renewed interest in increasing the thickness of an SCR graft to further prevent superior humeral head translation and diminish subacromial contact pressures and secondary radiographic, or more importantly, clinical failure. Some authors have sought to augment dermal allografts for increased stiffness, whereas other authors have explored the option of adding a separate graft on the undersurface of the acromion for a bursal acromial reconstruction. Although this increased graft thickness may result in improved acromiohumeral distance and clinically significant patient improvement, secondary graft retear and acromial osteolysis may develop due to increased friction or "overstuffing" of the subacromial space.

Shoulder Superior Capsular Reconstruction Hybrid Graft Thickness Greater Than Preoperative Acromiohumeral Distance Increases Graft Retear Rate and Subacromial Erosion

PURPOSE

To evaluate the impact of graft thickness on clinical outcomes and graft retear after superior capsular reconstruction (SCR) using a hybrid graft combining both fascia lata autograft and dermal allograft in patients with massive rotator cuff tear (MRCT).

METHODS

Between January 2017 and February 2019, this study enrolled 58 patients with MRCT who underwent SCR using a hybrid graft combining both fascia lata autograft and dermal allograft. We evaluated clinical outcomes and compared differences between the graft intact and the graft retear group. Moreover, subgroup analysis was performed for patients having a preoperative acromiohumeral distance (AHD) less than or equal to the used graft thickness (group 1) and the results were compared with those for preoperative AHD greater than the used graft thickness (group 2).

RESULTS

Fifty-five patients who underwent MRCT with a mean age of 65.1 ± 5.7 years old were followed up during a mean period of 30.5 ± 6.5 (range, 24-37) months. There were significant differences in clinical outcome measures preoperatively and postoperatively (P < .05). There were no significant differences in clinical outcomes between the graft intact and graft retear groups (P > .05). The subgroup analysis revealed that the retear (68.6% vs 30.4%, P = .004) and subacromial erosion rates (91.4% vs 60.9%, P = .005) were significantly greater in for patients having a preoperative AHD less than or equal to the used graft thickness (group 1).

CONCLUSIONS

SCR using a hybrid graft combining both fascia lata autograft and dermal allograft is promising with improved clinical scores (P < .05) irrespective of the graft integrity. The use of a graft with a thickness greater than a patient's preoperative AHD could increase graft retear and subacromial erosion rates after SCR. However, there was no significant difference in clinical outcomes according to the relationship between used graft thickness and preoperative AHD.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Anterior Cable Reconstruction: Prioritize Rotator Cable and Tendon Cord When Considering Superior Capsular Reconstruction

Although distinct in name, the anterior cable of the superior capsule and tendon cord of the supraspinatus are structurally one in the same at the attachment on the greater tuberosity footprint. Force transmission through both structures where they converge and interdigitate at this location is disproportionately high, which has implications on functional impact. Superior capsule reconstruction, and, specifically, the anterior cable of the superior capsule, has been shown to assist in maintaining superior stability and a functional fulcrum of the glenohumeral joint, without overconstraining range of motion. Anterior cable reconstructions have been described for specific indications, including full-thickness tears of the supraspinatus and anterior one-half of the infraspinatus. Cord-like grafts, including long head biceps tendon autografts and semitendinosus allografts, can provide relative technical ease during surgery compared to sheet-like grafts for this indication. Side-to-side sutures between anterior cable reconstruction graft and posterosuperior capsule retension the native capsule to optimize its natural functional role. Accounting for abduction and rotation at the time of fixation and employing "loop-around" fixation sutures (no sutures through the graft), are critical concepts to consider in terms of kinematics and limiting graft failure. With both the biomechanically and clinically based literature demonstrating functionality with maintenance of the superior capsule (and specifically the anterior cable of the capsule), despite rotator cuff tendon insufficiency or irreparability, the anterior cable of the superior capsule should be prioritized when considering full-thickness rotator cuff tears that naturally involve both the capsular cable and the supraspinatus tendon cord. LEVEL OF EVIDENCE: Level V (expert opinion).

Biomechanical Role of the Superior Capsule in a Rotator Cuff Sectioned and Repaired State: A Sequential Sectioning Study

BACKGROUND

Individual contributions of the rotator cuff (RC) and superior capsule (SC) to prevent superior translation of the humerus are not well understood.

PURPOSE

To evaluate the relative contributions of the SC and RC to normal and pathologic shoulder biomechanics by determining their independent effects on superior humeral translation.

STUDY DESIGN

Controlled laboratory study.

METHODS

Twelve cadaveric shoulders were tested at 0º, 45º, and 90º of abduction under 5 conditions: intact RC/SC, RC sectioned first, SC sectioned first, both structures sectioned, and RC repair. Matched pairs were randomly assigned to the second or third testing condition (RC or SC sectioned first). Specimens were tested under 2 static conditions (40-N deltoid load [balanced load], 80-N deltoid load [superiorly directed load]) and 1 dynamic condition during active abduction. A mixed-design 2-way repeated-measures analysis of variance with Bonferroni adjustments was performed to compare testing conditions. Paired t tests were used to compare specimens in the intact state versus the repaired state. Significance was set at P < .05.

RESULTS

During balanced deltoid loading at 0° and 45º, there was significantly greater humeral translation when both structures were sectioned as compared with the intact state and with both isolated sectioned states (P < .05 for all). No significant differences were observed between or within groups at 90º of abduction. These effects remained consistent with superiorly directed loading. Dynamic testing of both groups showed a significant increase in superior translation for specimens in which the RC was deficient versus the intact state (P = .027), with no difference when the SC was sectioned. The RC repair state returned translation to values similar to the intact state at all abduction angles and loading conditions (P > .05).

CONCLUSION

In this cadaveric study, the SC and RC played an important role in preventing superior humeral translation; however, dynamic testing suggested preferential contribution of the RC. RC repair was effective in preventing superior humeral translation, even with a sectioned SC at the level of the glenohumeral joint.

CLINICAL RELEVANCE

RC repair was effective in preventing superior humeral translation, even in the presence of a sectioned SC at the level of the glenohumeral joint in this cadaveric model. Our data lay the groundwork for future studies investigating the clinical effect of RC repair in an SC sectioned state.

Human Dermal Allograft Superior Capsule Reconstruction With Graft Length Determined at Glenohumeral Abduction Angles of 20° and 40° Decreases Joint Translation and Subacromial Pressure Without Compromising Range of Motion: A Cadaveric Biomechanical Study

PURPOSE

To compare the biomechanical effects of superior capsule reconstruction (SCR) graft fixation length determined at 20° and 40° of glenohumeral (GH) abduction.

METHODS

Humeral translation, rotational range of motion (ROM), and subacromial contact pressure were quantified at 0°, 30°, and 60° of GH abduction in the scapular plane in 6 cadaveric shoulders for the following states: intact, massive rotator cuff tear, SCR with dermal allograft fixed at 20° of GH abduction (SCR 20), and SCR with dermal allograft fixed at 40° of GH abduction (SCR 40). Statistical analysis was conducted using a repeated-measures analysis of variance and a paired t test (P < .05).

RESULTS

A massive cuff tear significantly increased total ROM compared with the intact state at 0° and 60° of abduction. SCR 20 or SCR 40 did not affect ROM. Compared with the intact state, the massive cuff tear model significantly increased superior translation by an average of 4.6 ± 0.5 mm in 9 of 12 positions (P ≤ .002). Both SCR 20 and SCR 40 reduced superior translation compared with the massive cuff tear model (P < .05); however, SCR 40 significantly decreased superior translation compared with SCR 20 at 0° of abduction (P ≤ .046). Peak subacromial pressure for the massive cuff tear model increased by an average of 486.8 ± 233.9 kPa relative to the intact state in 5 of 12 positions (P ≤ .037). SCR 20 reduced peak subacromial pressure in 2 of 12 positions (P ≤ .012), whereas SCR 40 achieved this in 6 of 12 positions (P ≤ .024).

CONCLUSIONS

SCR with dermal allograft fixed at 20° or 40° of GH abduction decreases GH translation and subacromial pressure without decreasing ROM.

CLINICAL RELEVANCE

With an increasing abduction angle for graft fixation, the medial-to-lateral graft length is decreased and the graft tension is effectively increased. Surgeons may increase shoulder stability without restricting ROM by fixing the graft at higher abduction angles. However, surgeons should remain cognizant of potential graft failure due to increased tension.

The choice of an optimal graft for the superior capsule reconstruction of the shoulder with a massive rotator cuff tear

Background: The study hypothesis is that the knowledge about the mechanical properties of biological tissues will help surgeons to choose a transplant. Aim: To determine the optimal type of a graft, based on the assessment of the mechanical properties of three types of grafts used for the superior capsule reconstruction of the shoulder joint with a massive rotator cuff tear. Methods: In the experimental work, 3 types of biological tissues were studied: allografts of the fascia lata and of the dura mater, and the DX Reinforcement Matrix (a dermal ECM xenograft). The experiment was divided into two parts. In the first part, the mechanical strength at rupture of the samples was evaluated and compared, in the second part the resistance of a vertical suture was studied. The tests included uniaxial stretching with the force and strain at rupture recorded. Results: The fascia lata allograft showed the highest ultimate tensile strength, while the dura mater allograft had the lowest ultimate tensile strength. All the three materials showed rather high values of the rupture strain. The lowest value of the rupture strain was detected for the dura mater allograft 15.22.6%, the highest value was obtained for the dermal ECM xenograft 63.320.8%. The largest value of the fracture stress was recorded for the DX Reinforcement Matrix 33.5 N. The minimum value was recorded for the fascia lata allograft 9.9 N. Conclusion: The fascia lata allograft and DX Reinforcement Matrix have the optimal mechanical characteristics and can be recommended as grafts for the superior capsule reconstruction of the shoulder joint with a massive rotator cuff tear.

Treatment Options for Massive Irreparable Rotator Cuff Tears

PURPOSE OF REVIEW

Massive irreparable rotator cuff tears present a significant challenge to the orthopedic surgeon. No single treatment, particularly among joint-preserving options, has been shown to be superior. The purpose of this review is to discuss recent advances in the treatment of massive irreparable rotator cuff tears, including partial repair with and without graft augmentation, interposition grafts, superior capsule reconstruction, subacromial balloon spacers, tendon transfer, and reverse total shoulder arthroplasty. We will also offer guidance on surgical indications based on our clinical experience.

RECENT FINDINGS

Partial repair may offer reasonable clinical improvement for patients with lower preoperative function despite high re-tear rates. Additionally, several types of interposition grafts have shown promising short-term results and may outperform repair alone. Subacromial balloon spacers may lead to clinical improvement, especially in patients without glenohumeral osteoarthritis or pseudoparalysis, and recently received FDA approval for use in the USA. Superior capsule reconstruction is a technically demanding procedure that appears to produce excellent short-term results particularly when performed at high volume, but long-term studies in heterogeneous study groups are needed. Tendon transfers improve function by restoring force coupling in the shoulder, offering a promising option for younger patients. Reverse total shoulder arthroplasty (RTSA) is a reliable option for treatment of irreparable cuff tears in elderly patients with lower functional demands. Irreparable cuff tears remain a difficult condition to treat. Recommended treatment for younger patients without glenohumeral osteoarthritis is particularly controversial. For older patients with low-demand lifestyles and glenohumeral osteoarthritis, RTSA is an effective treatment option. For all discussed procedures, patient selection appears to play a critical role in clinical outcomes.

The best options in superior capsular reconstruction

Irreparable massive rotator cuff tears cause pain, loss of function, and a decrease in range of motion, which cause serious disturbances in daily life. Young patients, in particular, are active and have relatively high functional requirements, and their surgical options are limited. Superior capsular reconstruction (SCR) was first proposed for irreparable massive rotator cuff tears, good clinical results have been reported in short-term follow up. Since then, SCR has been used increasingly worldwide for irreparable massive rotator cuff tears, and various studies have been published on clinical outcomes, biomechanical outcomes, surgical techniques, and graft types. This article reviews the optimal graft and surgical options for improving clinical outcomes in SCR.

Editorial Commentary: Mechanics Versus Biology: Both Are Relevant Principles in Understanding Superior Capsular Reconstruction

The topic of superior capsular reconstruction remains controversial. Whereas identifying the best time-zero graft configuration for this procedure remains important, the success or failure of the procedure will be dependent on the biology, not just the bench performance. Any conforming object placed in the subacromial space at time zero could center the humeral head and decrease superior translation compared with a massive rotator cuff tear but may not restore translation to normal. It does appear that a thicker graft is better in this regard, but how much thicker is better is unclear. Most of all, whether the mechanical benefits of a thicker graft will be offset by a thicker and potentially less biologically compatible construct is also unclear. In most orthopaedic settings, autografts remain consistently superior to allografts. The contrast in results may be better explained by biology, and the excellent superior capsular reconstruction results reported with autograft have not been replicated universally with dermal allograft.