Dermal allograft superior capsule reconstruction biomechanics and kinematics

The effects of medial soft tissue release for varus deformity during medial open wedge supramalleolar osteotomy: a cadaveric study

This study was performed to investigate the effects of fibular osteotomy and release of medial soft tissues including posterior tibial tendon (PTT), and deep deltoid ligaments, which act as medial stabilizing structures in medial open wedge SMO. Twelve fresh frozen human legs were obtained and disarticulated below the knee. Experiments were conducted in four steps. First, medial open wedge tibial osteotomy was performed. Second, fibular osteotomy was performed in an inferomedial direction at the same level as the tibial osteotomy. Third, the deep deltoid ligament was released from tibial attachments. Forth, total tenotomy of the PTT was performed behind the medial malleolus. After finishing each step, contact area and peak and mean pressures were measured in the tibiotalar and talofibular joints. Fibular osteotomy after medial open wedge SMO significantly decreased mean pressure in the tibiotalar joint, mean and peak pressures in the talofibular joint. Medial soft tissue release resulted in a remarkable lateral shift and decreased tibiotalar joint loading. However, no remarkable change was observed in the tibiotalar joint during releasing medial soft tissues. The overall peak pressure distribution tended to shift more laterally compared to the value of normal alignment. In conclusion, concomitant fibular osteotomy and release of the deltoid ligament and PTT provide a useful means of minimizing tibiotalar joint stress.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13534-024-00370-7.

Tuberoplasty reduces resistance force in dynamic shoulder abduction for irreparable rotator cuff tears: a cadaveric biomechanical study

BACKGROUND

Arthroscopic tuberoplasty is an optional technique for managing irreparable rotator cuff tears. However, there is a lack of studies investigating the resistance force during shoulder abduction in cases of irreparable rotator cuff tears and tuberoplasty.

HYPOTHESES

In shoulders with irreparable rotator cuff tears, impingement between the greater tuberosity (GT) and acromion increases the resistance force during dynamic shoulder abduction. Tuberoplasty is hypothesized to reduce this resistance force by mitigating impingement.

STUDY DESIGN

Controlled laboratory study.

METHODS

Eight cadaveric shoulders, with a mean age of 67.75 years (range, 63-72 years), were utilized. The testing sequence included intact rotator cuff condition, irreparable rotator cuff tears (IRCTs), burnishing tuberoplasty, and prosthesis tuberoplasty. Burnishing tuberoplasty refers to the process wherein osteophytes on the GT are removed using a bur, and the GT is subsequently trimmed to create a rounded surface that maintains continuity with the humeral head. Deltoid forces and actuator distances were recorded. The relationship between deltoid forces and actuator distance was graphically represented in an ascending curve. Data were collected at five points within each motion cycle, corresponding to actuator distances of 20 mm, 30 mm, 40 mm, 50 mm, and 60 mm.

RESULTS

In the intact rotator cuff condition, resistance forces at the five points were 34.25 ± 7.73 N, 53.75 ± 7.44 N, 82.50 ± 14.88 N, 136.25 ± 30.21 N, and 203.75 ± 30.68 N. In the IRCT testing cycle, resistance forces were 46.13 ± 7.72 N, 63.75 ± 10.61 N, 101.25 ± 9.91 N, 152.5 ± 21.21 N, and 231.25 ± 40.16 N. Burnishing tuberoplasty resulted in resistance forces of 32.25 ± 3.54 N, 51.25 ± 3.54 N, 75.00 ± 10.69 N, 115.00 ± 10.69 N, and 183.75 ± 25.04 N. Prosthesis tuberoplasty showed resistance forces of 29.88 ± 1.55 N, 49.88 ± 1.36 N, 73.75 ± 7.44 N, 112.50 ± 7.07 N, and 182.50 ± 19.09 N. Both forms of tuberoplasty significantly reduced resistance force compared to IRCTs. Prosthesis tuberoplasty further decreased resistance force due to a smooth surface, although the difference was not significant compared to burnishing tuberoplasty.

CONCLUSION

Tuberoplasty effectively reduces resistance force during dynamic shoulder abduction in irreparable rotator cuff tears. Prosthesis tuberoplasty does not offer a significant advantage over burnishing tuberoplasty in reducing resistance force.

CLINICAL RELEVANCE

Tuberoplasty has the potential to decrease impingement, subsequently reducing resistance force during dynamic shoulder abduction, which may be beneficial in addressing conditions like pseudoparalysis.

Influence of the rotator cuff tear pattern in shoulder stability after arthroscopic superior capsule reconstruction: a computational analysis

OBJECTIVES

To assess the ability of the arthroscopic superior capsule reconstruction (SCR) in restoring glenohumeral stability in the presence of different preoperative patterns of irreparable rotator cuff tears (RCTs).

METHODS

A computational musculoskeletal (MSK) model of the upper limb was used to simulate isolated SCR and to estimate the stability of the shoulder. Four patterns of preoperative irreparable RCTs were modeled: Supraspinatus (SSP); SSP ​+ ​Subscapularis (SSC); SSP ​+ ​Infraspinatus (ISP); and SSP ​+ ​SSC ​+ ​ISP. The muscles involved in the irreparable RCT were removed from the MSK model to simulate an irreparable full-thickness tear. In the MSK model, the muscle and joint forces were estimated for a set of upper limb positions, from four types of motions (abduction in the frontal plane, forward flexion in the sagittal plane, reaching behind the back, and combing the hair) collected in a biomechanics laboratory, through inverse dynamic analysis. The stability of the shoulder was estimated based on the tangential and compressive components of the glenohumeral joint reaction force. The comparison of pre- and post-operative conditions, for the four patterns of irreparable RCTs, with the healthy condition, was performed using ANOVA and Tukey's tests (statistical level of p ​< ​0.05).

RESULTS

In the setting of an isolated irreparable SSP tear, SCR statistically significantly improved stability compared with the preoperative condition (p ​< ​0.001). For the irreparable SSP ​+ ​SSC pattern, a statistically significant loss in stability was observed (p ​< ​0.001) when SCR was applied. For the irreparable SSP ​+ ​ISP and SSP ​+ ​SSC ​+ ​ISP patterns, the postoperative condition increased shoulder stability, compared to the preoperative condition; however, the improvement was not statistically significantly different.

CONCLUSION

Isolated SCR for irreparable RCTs extending beyond the SSP does not statistically significantly improve the stability of the glenohumeral joint.

LEVEL OF EVIDENCE

Level IV.

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.

The Number of Surgeons Using Superior Capsular Reconstruction for Rotator Cuff Repair Is Declining

Purpose

To investigate surgeon preferences for graft use, including biologic augmentation and superior capsular reconstruction (SCR) associated with surgical treatment of rotator cuff repair (RCR).

Methods

A 26-question survey was completed by arthroscopic shoulder surgeons. Surgeon demographics were evaluated. Surgeons were queried about shoulder arthroscopic graft use and rationale then responses were analyzed based on demographics.

Results

In total, 260 surgeons completed the survey. Fifty-one percent of surgeons reported a decrease in the volume of SCR use in the past 5 years. Less than 3% of surgeons used SCR in >90% of irreparable RCR cases, compared with 38% using SCR in <10% of irreparable cases (P < .05). Surgeons performing >100 RCR annually (42%; P < .05) and those employed in the hospital setting (44%; P < .05) reported an overall increase in the use of SCR. More international surgeons (67%) decreased their use of SCR compared with U.S. surgeons (44%; P < .05). In contrast, bioinductive graft use is generally on the rise, with 48% of surgeons reporting increased use since first use, although used in <10% of cases by 54% of surgeons. Sixty-eight percent of surgeons performing >100 RCRs annually used bioinductive grafts (P < .05). Fewer international surgeons (30%) performed biologic augmentation (P < .05). Suboptimal published outcomes (40%) and no perceived patient benefit (40%) were most cited for decreased SCR use. Surgeons reporting increased use cited improved personal patient outcomes (72%).

Conclusions

Arthroscopic surgeons report decrease in volume of SCR use in the past 5 years. Surgeon's personal experience of patient outcome and suboptimal published results were the strongest factors impacting decision-making. In contrast, bioinductive graft use is increasing. However, most surgeons use these grafts in a relatively small percentage of cases.

Clinical Relevance

Evaluation of scientific data, personal experience, and influences on surgical practice will give a comprehensive understanding of current RCR practices.

Irreparable Massive Rotator Cuff Tears: Subacromial Balloon Surgical Technique

Massive irreparable rotator cuff tears pose a significant challenge for both the treating orthopedic surgeon and patient. Surgical treatment options for massive rotator cuff tears include arthroscopic debridement, biceps tenotomy or tenodesis, arthroscopic rotator cuff repair, partial rotator cuff repair, cuff augmentation, tendon transfers, superior capsular reconstruction, subacromial balloon spacer, and ultimately reverse shoulder arthroplasty. The present study will provide a brief overview of these treatment options along with a description of the surgical technique for subacromial balloon spacer placement.

The clinical outcomes of infraspinatus rotational transfer for irreparable posterosuperior rotator cuff tears: a preliminary report

Background

This study aimed to examine the preliminary clinical results of the infraspinatus rotational transfer procedure for irreparable posterosuperior rotator cuff tears.

Methods

This study included 34 patients (mean age, 68.4 years). Their mean tear width and length measurements were 50.9 mm and 50.6 mm, respectively. The functional outcomes, including physician-determined and patient-reported scores, were evaluated before and at 1 year after surgery. The structural outcomes determined using the magnetic resonance imaging examination results were also assessed.

Results

The clinical scores significantly improved after surgery compared with the scores before surgery: the Constant-Murley score (53.3±21.1 to 76.8±10.5), University of California at Los Angeles Shoulder score (15.6±3.6 to 27.8±6.7), American Shoulder and Elbow Surgeons Shoulder score (51.8±18.3 to 89.1±13.5), and WORC score (925.0±436.8 to 480.3±373.2) (all p<0.001). Postoperative re-tears were noted in two patients (5.9%).

Conclusions

One year postoperatively, the patient’s clinical scores significantly improved, with a re-tear rate of 5.9%.

Long head of biceps transfer to augment Bankart repair in chronic anterior shoulder instability with and without subcritical bone loss: a biomechanical study

BACKGROUND

Treating recurrent anterior shoulder instability in participants in collision sports, patients with capsulolabral defects, and patients with bipolar bone loss remains challenging. The study purpose was to investigate the effect of long head of the biceps transfer (LHBT) on load-to-dislocation biomechanics in a repetitive serial shoulder dislocation cadaveric model comparing LHBT with the Latarjet and Bankart procedures-the first-line treatment methods for chronic traumatic anterior shoulder instability with and without anterior glenoid bone loss, respectively.

METHODS

In this controlled laboratory study, 8 fresh-frozen cadaveric shoulders with different conditions were dislocated in sequence using a custom test frame. The muscle loading configuration simulated the arm in the apprehension position, and biceps loads of 20 N and 40 N were used for the static glenohumeral position analysis to evaluate the sling effect. Sequential experimental conditions consisted of the intact state, second and third dislocations, chronic instability, Bankart repair, first LHBT, subcritical glenoid bone loss, second LHBT, and Latarjet procedure.

RESULTS

The pectoralis major and joint reaction loads to dislocation sequentially decreased with serial dislocations in all specimens, with the lowest value in the subcritical glenoid bone defect condition. In the setting of chronic instability, the pectoralis load to dislocation was significantly higher with the Bankart repair (P = .031) and LHBT (P < .001), at 71% and 85% of the intact value, respectively. Direct comparison of the pectoralis load to dislocation favored LHBT over Bankart repair (P = .015). In the subcritical defect scenario, LHBT did not significantly increase the load to dislocate, and the Latarjet procedure demonstrated a higher load to dislocate than LHBT (P < .001). All 3 surgical procedures tested significantly increased the angle of horizontal abduction at the time of dislocation and restored the glenohumeral position to closer to the intact state. Doubling the biceps load leveraged the sling effect, pulling the humeral head farther posterior-superiorly, but this was not enough to overcome the effect of a 20% subcritical glenoid bone defect.

CONCLUSIONS

In a serial dislocation model, LHBT effectively stabilized the glenohumeral joint in a simulated chronic instability scenario, increasing the pectoralis major load-to-dislocate and glenohumeral joint reaction force components at the time of dislocation and restoring relative glenohumeral positioning to close to the intact state. The Latarjet procedure outperformed LHBT in stabilizing shoulders in the 20% subcritical glenoid bone defect condition.

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.

Superior Capsular Reconstruction: Proposed Biomechanical Advantages

The intact rotator cuff provides dynamic stability for the glenohumeral joint through range of motion by compressing the humeral head to the center of the glenoid. Maintenance of articular congruity provides a stable fulcrum for the more forceful muscles of the shoulder girdle. Massive rotator cuff tears disrupt the concavity-compression mechanism and lead to unopposed superior pull of the deltoid. As a result, superior migration of the humerus, abutment of the acromion, and, in some cases, progression to cuff tear arthropathy occur. Arthroscopic superior capsular reconstruction has emerged as an effective treatment in select indications. Several potential biomechanical advantages to SCR have been described on the basis of cadaver studies. By tethering the greater tuberosity to the glenoid, superior migration is resisted, and the center of rotation is stabilized. The interpositional spacer effect describes reduced subacromial contact pressure, and the reduction is greater with thicker grafts. Side-to-side suturing of the graft to residual tendon and capsule achieves capsular continuity and may further improve the stabilizing function of the residual capsule and prevent medial-lateral elongation of the graft. Although these biomechanical principles overlap to some degree, their summation offers an explanation for the improved pain and function seen in patients who undergo superior capsular reconstruction.

Biologic Tuberoplasty With an Acellular Dermal Allograft for Massive Rotator Cuff Tears

We present the technique of biologic tuberoplasty, where an acellular dermal allograft is used to cover the tuberosity in patients with massive irreparable cuff tears to prevent bone-to-bone contact between the tuberosity and acromion when active elevation is attempted. This technique can be performed in patients with massive rotator cuff tears who are low-demand and have significant medical comorbidities, poor bone quality, or who are not candidates for a reverse shoulder arthroplasty or who cannot tolerate a lengthy rehabilitation protocol. It is less time-consuming than a superior capsule reconstruction and more bone-sparing than traditional tuberoplasty. Patients with massive rotator cuff tears involving the supraspinatus and a portion of the infraspinatus lose their force couple, leading to superior humeral head migration with abutment of the tuberosity against the acromion upon deltoid activation. The center of rotation moves superiorly with deltoid contraction, developing an acromiohumeral articulation. This results in bone-to-bone contact between the acromion and humerus, leading to pain and acetabularization of the acromion over time. Coverage of the tuberosity with the acellular dermal allograft acts as an interpositional tissue and prevents bone-to-bone contact between the tuberosity and acromion.