Longitudinal efficacy of acellular dermal allograft following superior capsular reconstruction of irreparable rotator cuff tears

Abstract

Background

Superior capsular reconstruction (SCR) remains an option for irreparable rotator cuff tears, especially for active patients. While fascia lata grafts were first used with SCRs, acellular dermal allografts have demonstrated similar postoperative outcomes and complication rates. Few studies report long-term clinical outcomes following use of acellular dermal allografts. The aim of the current study is to evaluate long-term efficacy of allograft usage in SCR through patient reported clinical outcomes.

Methods

A retrospective review of patients undergoing SCR with use of dermal allografts from 2015 to 2021 was performed. Exclusion criteria included patients lost to follow up, revision or removal of graft, and inadequate follow up timepoints. Demographics and operative characteristics were collected. To evaluate efficacy of graft, numerical rating scale (NRS), American Shoulder and Elbow Score (ASES) were assessed postoperatively. Shoulder range of motion (ROM) was also evaluated by the 6-month postoperative timepoint. Improvement in NRS, ASES, and shoulder ROM from baseline values were evaluated using a t-test.

Results

The final cohort was 21 patients with two patients undergoing revision and removal of the graft. Mean follow up time was 36.9 months. No major postoperative complications were recorded. Mean preoperative NRS and ASES score was 5.7 and 38.4, which both significantly improved postoperatively (p < 0.001). Patients demonstrated improvements in forward flexion, abduction in 90° rotation, and external and internal rotation.

Conclusion

Use of acellular dermal grafts in SCR procedures for irreparable rotator cuff tears remains a viable long-term solution to restore shoulder function.

1. Introduction

Rotator cuff tears are among the most common injuries adults face on an annual basis and is especially prevalent among the elderly population.¹ Injuries can range from partial to full thickness tears, which is reported to occur in over 20% of the adult population.² Symptoms range from asymptomatic pain to debilitating pain causing a limitation in range of motion and muscle strength. Among full thickness tears, 35–41% of individuals report symptomatic pain and 10–21% are asymptomatic.2, 3, 4, 5 Although a number of meta-analyses have established that conservative and operative management may provide equivalent relief of symptoms,^6,7 instances where pain is intractable or functionality of the joint is lost may cause surgeons to favor surgery. A number of options are available for surgical treatment, including partial rotator cuff repair, reverse shoulder total arthroplasty, and bridging rotator cuff reconstruction through use of a graft. However surgical options are limited by chronic tendon retraction, atrophy and fatty infiltration.^8,9 Surgeons must also consider the quality of life of their patients during preoperative counseling.

While performing a total reverse shoulder arthroplasty is reported to result in significant improvement in symptoms and physical function, a benefits may be ideal for a patient population >65 years.¹⁰ Individuals seeking to retain the ability of full range of motion (ROM), who still live relatively active lives, or have intact articular cartilage may opt for other surgical options. While a host of options exist that may address this particular need of a patient, bridging rotator cuff reconstruction through grafts has become an option that has demonstrated desired results among active patient populations.¹¹ In particular, superior capsular reconstruction has been reported, to provide better protection against proximal humeral head migration as compared to interposition grafts.^12,13

Since it was first introduced by Mihata et al.,¹² SCR has undergone significant change with respect to the type of graft used and few if any studies have provided some form of longitudinal data. Their follow-up study of 23 patients who received SCR with fascia lata graft demonstrated that after an average of 34 months patients showed improvement in the American Shoulder and Elbow Surgeons (ASES) score as well as increased functional outcomes such as range of motion and muscle strength.¹² Although promising, the fascia lata graft is thin and requires doubling of the graft and large incisions to obtain donor grafts, increasing surgical time and donor site morbidity.¹⁰ To address these deficiencies, others have adapted Mihata's technique through the use of an acellular dermal allograft for SCR. This allograft is prepared to retain extracellular material, thereby permitting retention of key biochemical and biomechanical properties. Early reports outline key advantages of acellular dermal allografts as ease of preparation, thickness and strength of construct and lack of donor site morbidity.¹⁰ Early results demonstrate that the acellular dermal allograft provided a 70% success rate at 17 months, as well as similar or better clinical outcomes such as return of function, reduction in pain, and increased range of motion as compared to fascia lata grafts.¹⁴

Although the benefits of use of an acellular dermal graft may be eventually realized, there are few studies that provide a longitudinal outlook of the improvement SCR can provide to patients. Therefore, the purpose of this study is to provide a long term assessment of the efficacy of allograft usage in superior capsular reconstruction procedures in hopes of further substantiating its use for treatment of irreparable rotator cuff tears. Our hypothesis is that patients undergoing an SCR using an acellular dermal graft will demonstrate significant improvement in their shoulder function.

2. Materials and methods

2.1. Inclusion and exclusion criteria

In accordance with our institution's ethical guidelines, Institutional Review Board approval was obtained prior to commencement of the study. A retrospective chart review was performed for eligible arthroscopic SCR procedures for irreparable rotator cuff tears between August 2015 and June 2021. Inclusion criteria for this study included patient age ≥18 years, underwent arthroscopic SCR surgery using acellular human dermal allograft with a minimum postoperative follow up length of ≥ 6-months. Exclusion criteria included patients <18 years, patients lost to follow up, revisions of arthroscopic SCR for graft failure, or removal of acellular human dermal allograft. Patients lost to follow up were defined as individuals who did not appear for postoperative follow up appointments prior to the 6-month timepoint. All patients included in this study underwent arthroscopic SCR for an irreparable rotator cuff tear.

2.2. Data collection

Demographic information was collected, which included age, gender, ethnicity, body mass index (BMI), active smoker status, and diabetic status. Additionally, perioperative information was gathered for total operative time (skin incision to skin closure), estimated intraoperative blood loss, day of discharge, and rates of major medical complications. Primary outcomes measures were collected as patient reported outcome measures (PROM), which included the American Shoulder and Elbow Surgeons score (ASES) and Numerical Rating Scale (NRS). ASES were calculated on a 100-point scale with points weight 50% for pain and 50% for function. 50% pain score was calculated based on NRS scores as follows, (10-NRS) * 5 for a total of 50 points. The 50% function was based on a separate 10-item questionnaire (Appendix A) with each question graded on an ordinal scale of 0–3 for a maximum score of 30. Raw scores were multiplied by 5/3 for a maximum function score of 50. Both ASES and NRS scores were collected at the preoperative timepoint as well as at the final postoperative follow up visit. Secondary outcomes of interest were shoulder range of motion (ROM) as defined by active forward flexion, rotation at 90° abduction, active internal rotation, and active external rotation. ROM was collected at the 12-week, 18-week, 24-week, 32-week, 1-year and final postoperative visit.

2.3. Surgical technique

Preoperative assessment of a massive irreparable rotator cuff tear was performed through magnetic resonance imaging (Fig. 1). The senior authors’ current surgical technique for SCR using acellular human dermal allograft (3.0 mm thickness) is briefly described below. Patients were placed in the beach chair position and diagnostic arthroscopy was performed through a posterior portal. Intra articular debridement was performed, and any torn or frayed labral tissue cleared. Following debridement, a thorough subacromial decompression and acromioplasty was performed. Tear in the rotator cuff and retracted nature were confirmed and bicep tenodesis completed. Two anchors were then drilled into the superior glenoid spanning from the anterior to posterior border (Fig. 2). Four dimensions were measured using an arthroscopic probe to determine the size of the acellular dermal allograft. The dermal allograft was introduced and firmly anchored to the glenoid and humerus using a lateral and medial row (Fig. 2). Fixation was confirmed for quality and then arthroscopy terminated. Patients were followed up postoperatively in clinic to determine success of graft placement (Fig. 3).

Fig. 1.

Preoperative magnetic resonance image of coronal (A) and sagittal (B) plane of a massive, retracted rotator cuff tear.

Fig. 2.

Superior view (A) of the glenoid and humeral head with suture anchors placed in the glenoid. Note the rotator cuff is not visible. Dermal allograft (*) fixed medially (B) and laterally (C).

Fig. 3.

Postoperative magnetic resonance image of coronal (A) and sagittal (B) plane of intact repair 1 year postoperatively.

2.4. Statistical analysis

Descriptive statistics of all baseline and operative characteristics for the cohort were performed. Comparison of pre-operative and post-operative ASES and NRS scores were done using a two-tailed Student's t-test. Additionally, differences in preoperative and postoperative active shoulder range of motion were also evaluated using a two-tailed Student's t-test. All statistical analysis was performed using RStudio (RStudio, PBC, Boston, MA) using an ɑ value of 0.05.

3. Results

3.1. Patient cohort

Retrospective chart review identified a total of 26 patients who underwent a superior capsular reconstruction. After inclusion and exclusion criteria were applied, 21 patients made up the final cohort, with 1 patient lost to follow up, 2 patients undergoing a revision and removal of graft, and 2 patients not meeting the minimum follow up. Both patients requiring removal of graft were indicated for failure of the graft and a partial repair was not attempted. Mean follow up time was 36.9 months. A summary of the patient baseline characteristics can be found in Table 1. The cohort had a mean age of 64.0 years (range 46–75 years) with a mean BMI of 29.9 kg/m². Majority of patients were male (90.5%) and carried a preoperative American Society of Anesthesiologist (ASA) score of 2. A summary of perioperative characteristics can be found in Table 2. Majority of procedures were performed on the right shoulder (57.1%), with most patients being of right-hand dominance (90.5%). Mean operative time was 116 ± 12 min with all patients having minimal blood loss and discharged on the same day of surgery (POD 0). No major postoperative complications were recorded for all patients.

Table 1.

Patient demographics.

Characteristic	Total (n = 21)
Age (mean ± SD, years)	64.0 ± 6.8
40–49 years	4.7% (1)
50–59 years	14.3% (3)
60–69 years	52.4% (11)
70+ years	28.6% (6)
Gender
Male	90.5% (19)
Female	9.5% (2)
BMI (mean ± SD, kg/m2)	29.9 ± 6.7
Diabetic Status
Non-Diabetic	95.2% (20)
Diabetic	4.8% (1)
Smoking Status
Non-Smoker	90.5% (19)
Smoker	9.5% (2)
Ethnicity
Caucasian	95.3% (20)
African American	4.7% (1)

BMI = Body Mass Index; SD = standard deviation.

Table 2.

Perioperative characteristics.

Characteristic	Total (n = 21)
Laterality
Left	42.9% (9)
Right	57.1% (12)
Hand Dominance
Left	9.5% (2)
Right	90.5% (19)
Operative Time (Mean ± SD; min)	116 ± 12
Reported Estimated Blood Loss	Minimal
Day of Discharge POD 0	100.0% (21)

POD = Postoperative day.

3.2. Improvement in pain and function

Patients included in the study reported a mean baseline preoperative NRS score of 5.7 ± 2.8, which demonstrated significant improvement postoperatively to 0.22 ± 0.67 (p < 0.001), which represented a mean percent change of 95.5% (Table 3). In terms of shoulder function, patients improved their ASES score by a mean of 270.6% with the mean score at baseline of 38.4 ± 22.2 increasing to 100.0 ± 0.0 (p < 0.001) at final follow-up (Table 3).

Table 3.

Patient reported outcomes.

PROM	Mean ± SD	Δ (%)	*p-value
NRS
Preoperative	5.7 ± 2.8	–	–
Final Postoperative	0.2 ± 0.7	95.5	<0.001
ASES
Preoperative	38.4 ± 22.2	–	–
Final Postoperative	100.0 ± 0.0	270.6	<0.001

*p-values calculated using t-test.

Boldface indicates statistical significance.

3.3. Improvement in range of motion

A summary of all postoperative physical exam findings can be found in Table 4. At the preoperative timepoint, patients were limited in forward flexion from 0° to 112° and demonstrated significant improvements at all postoperative timepoints (p ≤ 0.029) except for 12-weeks and 32-weeks. Alternatively, patients had a mean rotation at 90° abduction of 77.3, which did not demonstrate any significant differences by the 1-year timepoint (p > 0.05). In terms of external rotation improvements, patients reported a baseline value of 28.7° and were able to show improvements at all postoperative timepoints up to 1-year but did not reach statistical significance (p > 0.05, all). Lastly, patients at best were able to internally rotate their shoulder to the L5 spinal level. Postoperatively, the majority of patients were able to demonstrate an improvement with most able to internally rotate to the L3 vertebral level.

Table 4.

Patient physical exam.

	Mean ± SD	*p-value
Forward Flexion
Preoperative	111.7 ± 31.2	–
12-weeks	125.4 ± 28.2	0.185
18-weeks	140.9 ± 28.1	0.011
24-weeks	135.8 ± 26.3	0.019
32-weeks	137.9 ± 28.8	0.065
1-year	150.0 ± 23.8	<0.001
>1-year	148.8 ± 14.4	0.029
Rotation at 90° Abduction
Preoperative	77.3 ± 17.2	–
12-weeks	90.0 ± 0.0	–
18-weeks	40.0 ± 8.7	0.002
24-weeks	64.0 ± 26.1	0.329
32-weeks	76.7 ± 11.5	0.941
1-year	76.7 ± 11.5	0.941
>1-year	70.0 ± 0.0	–
External Rotation
Preoperative	28.7 ± 8.2	–
12-weeks	27.7 ± 13.0	0.794
18-weeks	32.8 ± 12.5	0.391
24-weeks	29.6 ± 8.6	0.785
32-weeks	29.2 ± 5.8	0.889
1-year	30.7 ± 6.7	0.532
>1-year	28.3 ± 7.6	0.934
Internal Rotation1
Preoperative	L5 Level
12-weeks	L5 Level
18-weeks	L3 Level
24-weeks	L5 Level
32-weeks	L5 Level
1-year	L3 Level
>1-year	L3 Level

¹value represents the mode of spinal levels reported.

*p-values calculated using t-test.

Boldface indicates statistical significance.

4. Discussion

With rotator cuff injuries accounting for the majority of shoulder injuries, there has been an increase in both conservative and surgical options available to patients of all ages and demographics. While rotator cuff repairs have shown to be successful across a wide variety of injuries, limited options exist for patients with irreparable tears. Past studies have reported the success of reverse total shoulder arthroplasty for such types of injuries; however, success has largely been reported among patients >65 years.¹⁵ The subsequent development of surgical techniques with use of fascia lata grafts provided an option for patients with irreparable repairs who either remain active or were of a younger demographic.^12,13 However, while the use of such graft has proven beneficial for irreparable repairs, more recently acellular dermal allografts have become of great interest for use in superior capsular reconstruction procedures. As a recent development for the use of irreparable rotator cuff repairs, a consensus on its efficacy in SCR procedures is yet to be determined. This study demonstrated that recipients of the allograft have demonstrated longitudinal improvements in pain, disability, and physical function.

Although it is suggested that SCR is optimal for younger active patients without signs of osteoarthritis,^16,17 our cohort had a mean age of 64.0 years, which may be considered a less ideal population to benefit from this procedure. Prior studies have reported that augmentation of SCR procedures demonstrates similar outcomes between both younger and older patient populations.¹⁸ Similar to prior studies, older patients of our study demonstrated similar outcomes as their younger counterparts and did not have signs of graft failure. Such a result may suggest that SCR may not be limited solely to a younger population and may offer the elderly an additional option for treatment before undergoing arthroplasty.

Success of procedures traditionally has been assessed using a number of objective measures such as radiographic images and physical exam findings; however, with medicine shifting towards being patient centered, the use of patient reported outcomes has become increasingly important.¹⁹ Our study placed an emphasis on first assessing the improvement in shoulder and neck pain through the use of the NRS. A significant improvement in NRS scores was demonstrated among all postoperative groups, which aligns well with previous studies that utilized either acellular dermal grafts or fascia lata grafts.^{13,14,17,20,21} The current study add to the increasing number of investigations that support the use of grafts during an SCR procedure to alleviate pain due to irreparable rotator cuff tears. In addition to the improvement in pain, the use of ASES provides a patient reported objective measure for clinicians to track their patient's postoperative functional progress. Alternative psychometrics are also available to perform a similar assessment and includes the Shoulder Pain Disability Index (SPADI) and shortened Disability of the Arm, Shoulder, and Hand (quick DASH).^22,23 Prior studies compared the use of all three questionnaires and were able to demonstrate that the ASES score had similar reliability, convergent validity, discriminant validity, and internal validity.²⁴ Given the specificity of the questionnaire for evaluation of rotator cuff patients, we demonstrated that our cohort had a significant improvement in shoulder function following SCR for irreparable tears.

To the author's knowledge, few, if any, other studies have reported improvement of ASES over 4 years postoperatively; however, several investigators have reported a similar improvement in ASES up to 34 months or at minimum 2-years postoperatively.²⁰ Burkhart et al. also reported that ASES improved from a preoperative level of 52 to a 2-year postoperative value of 89.²⁰ Additionally, Hirahara et al.²⁵ reported a mean preoperative ASES value of 43.5, which significantly improved to 86.5 with a mean follow up time of 32 months. In contrast to previous studies, patients included in our study reported a substantially worse preoperative ASES score, with the 4-year group being the lowest at 22.5. Conversely, we saw an average ASES score of 100 indicative of patients experiencing no pain and functional limits following SCR. This may be more of a reflection of the full resolution of pain and gain of function due to a longer mean postoperative follow up time of 36.9 months, or it may also be a limitation of our smaller cohort with increased attrition rates affecting the mean ASES score. Nevertheless, our patients still demonstrated a significant improvement in ASES scores and these results, along with others, may suggest that use of a dermal allograft may require a longer postoperative course of recovery to regain shoulder function to pre-injury or presurgical levels.

Beyond patient reported outcome measures, improvements in shoulder range of shoulder motion proves equally as important. Given that irreparable rotator cuff tears can cause significant reduction in shoulder mobility such as forward flexion and external rotation, significant improvements in these areas can provide considerable benefits to a patient's quality of life.²⁶ Our study cohort reported to a considerable baseline impairment of forward flexion (<130°) and external rotation (<40°), which were similar to preoperative physical exam findings by Burkhart et al.²⁰ Additionally, our patients also demonstrated a noticeable improvement in forward flexion of over 30°. It must be noted that although the final postoperative ROM demonstrated were either similar or improved from their respective preoperative value, we did observe a decrease in rotation at 90° abduction at the 18-week timepoint. It could be postulated that this decrease was a result of limitations due to pain as it coincided with the commencement of active ROM exercises, in particular overhead maneuvers that improve scapular stability. Alternatively, this drop in value may also be a result of a smaller cohort and future studies with larger populations should observe any decrease in ROM during the postoperative course. Nevertheless, with our results being similar to previous studies, this study provided additional evidence that substantiates the claim that SCR may provide significant improvement to shoulder function at both preliminary and long term postoperative timepoints following an SCR.^14,20,27 These improvements in both short term and long term cohorts may imply that the use of the dermal allograft is appropriate for restoration of pre-injury ROM and could suggest a significant role in maintaining mobility in the shoulder for a more long term time period.

4.1. Limitations

There are several limitations that should be considered with this study. First, our patient cohort was limited to 21 individuals and considerably more power for analysis would be gained with a higher total number. Additionally, these patients spanned over a time period of over 6 years and all underwent a SCR by a single attending physician at a single institution, which may limit the generalizability of our results. Future studies reporting findings from multiple centers and additional surgeons may further substantiate our findings and strengthen our study. Moreover, while we were able to report on objective and subjective measures through physical exam findings and patient reported outcomes, the addition of radiographic analysis of graft integrity through either ultrasound or magnetic resonance imaging may further strengthen the claims of use of dermal allografts for SCRs. However, neither are currently considered standard of care and should be considered for future studies.

5. Conclusions

Patients with irreparable rotator cuff tears demonstrated significant benefits from undergoing a SCR with dermal allograft with both pain and function significantly improving postoperatively. In terms of range of motion, patients experienced significant improvements in forward flexion and saw the ability to externally and internally rotate their shoulder improve. Use of a dermal allograft did not lead to any postoperative complications and no patients were reported as having a failed procedure. These results suggest that while the use of dermal allografts have been a recent development in superior capsular reconstruction surgeries, their long-term outlook is believed to be equally beneficial as the current standard of care and may permit patients to retain functionality in their shoulder and avoid other surgical options that may result in restrictions of the shoulder function.

CRediT authorship contribution statement

Elliot D.K. Cha: Conceptualization, Data curation, Formal analysis, Methodology, Writing – review & editing. Kelly Shultz: Data curation, Formal analysis, Data curation. Kelley Chan: Data curation, Data curation. Joseph Choi: Conceptualization, Data curation, Methodology, Writing – review & editing, Supervision.

Appendix A. Supplementary data

The following is the Supplementary data to this article: