Biomechanical analysis of latissimus dorsi tendon transfer with and without superior capsule reconstruction using dermal allograft

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.

Superior Capsular Reconstruction Combined With Lower Trapezius Tendon Transfer Improves the Biomechanics in Posterosuperior Massive Rotator Cuff Tears

BACKGROUND

Surgical treatments for chronic posterosuperior massive rotator cuff tear (MRCT) are still controversial. Superior capsular reconstruction (SCR), which provides a static stabilizer to decrease superior humeral head translation, and lower trapezius tendon transfer (LTTT) with centralization of the humeral head, which prevents superior humeral head migration, are potential surgical options. To date, SCR combined with LTTT has not been fully investigated.

HYPOTHESIS

Restoration of static stabilizer and dynamic stabilizer together would effectively improve shoulder kinematics in posterosuperior MRCT.

STUDY DESIGN

Controlled laboratory study.

METHODS

A custom-made shoulder mechanics testing system was used to test 8 fresh-frozen cadaveric shoulders. The testing conditions were as follows: (1) intact; (2) posterosuperior MRCT (supraspinatus and infraspinatus removed); (3) SCR using the fascia lata; (4) LTTT; and (5) SCR combined with LTTT. The total rotational range of motion (ROM), superior translation, anteroposterior translation, and peak subacromial contact pressure were evaluated at 0°, 30°, and 60° of shoulder abduction. Repeated-measures analysis of variance and Tukey post hoc tests were performed.

RESULTS

The total rotational ROM, superior translation, anteroposterior translation, and peak subacromial contact pressure increased in posterosuperior MRCTs (all, P < .05). The rotational ROM, superior translation, anteroposterior translation, and peak subacromial contact pressure at 0° and 30° of shoulder abduction decreased in SCR (all, P < .05). However, there was no significant improvement in rotational ROM, superior translation, and peak subacromial contact pressure at 60° of shoulder abduction (P > .05). LTTT resulted in a significant decrease in the superior translation, anteroposterior translation, and peak subacromial contact pressure at 0°, 30°, and 60° of shoulder abduction (P < .05). SCR combined with LTTT restored the total rotational ROM, superior translation, anteroposterior translation, and peak subacromial contact pressure at 0°, 30°, and 60° of shoulder abduction (all, P < .05).

CONCLUSION

In the cadaveric model, SCR combined with LTTT showed improved shoulder kinematics and contact pressures in the posterosuperior MRCT model compared with SCR or LTTT alone.

CLINICAL RELEVANCE

SCR combined with LTTT may be regarded as an alternative surgical procedure for posterosuperior MRCTs.

Combined Arthroscopic-Assisted Lower Trapezius Tendon Transfer and Superior Capsule Reconstruction for Massive Irreparable Posterior-Superior Rotator Cuff Tears: Surgical Technique

Primary or revision irreparable rotator cuff tears remain a challenge. Clear algorithms do not exist. Several joint-preserving options are available, but no technique has been definitely proven to be better than another. Although superior capsule reconstruction has been shown to be effective in restoring motion, lower trapezius transfer can provide strong external rotation and abduction moment. The aim of the present article was to describe an easy and reliable technique to combine both options in 1 surgery, aiming to maximize the functional outcome by getting motion and strength back.

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.

Biomechanical analysis of progressive rotator cuff tendon tears on superior stability of the shoulder

BACKGROUND

The biomechanical relationship between irreparable rotator cuff tear size and glenohumeral joint stability in the setting of superiorly directed forces has not been characterized. The purpose of this study was to quantify kinematic alterations of the glenohumeral joint in response to superiorly directed forces in a progressive posterosuperior rotator cuff tear model.

METHODS

Nine fresh-frozen cadaveric shoulders (mean age; 58 years) were tested with a custom shoulder testing system. Three conditions were tested: intact, stage II (supraspinatus) tear, stage III (supraspinatus + anterior half of infraspinatus) tear. At each condition, range of motion and humeral head positions were measured with a "balanced" loading condition, and with a superiorly directed force ("unbalanced loading condition"). At each of the 0°, 20°, and 40° of glenohumeral abduction positions, all measurements were made at 0°, 30°, 60°, and 90° of external rotation (ER). Two-way repeated measures analysis of variance with Tukey post hoc tests were performed for statistical analyses.

RESULTS

With the balanced load, no significant change in superior humeral head position was observed in stage II tears. Stage III tears significantly changed the humeral head position superiorly at 30° and 60° ER at each abduction angle compared with the intact condition (P ≤ .028). With superiorly directed load, stage II and stage III tears both showed statistically significant increases in superior translation at all degrees of ER for all degrees of abduction (P ≤ .035), except stage II tears at 0° ER and 40° abduction (P = .185) compared with the intact condition. Stage II tears showed posterior translations with 30° and 60° ER, both at 20° and 40° of abduction. Stage III tears also showed posterior translations with 90° ER for all abduction angles (P ≤ .039).

CONCLUSION

With superiorly directed loads, complete supraspinatus tendon tears created superior translations at all abduction angles, and posterior instability in the middle ranges of rotation for 20° and 40° of abduction. Larger tears involving the anterior half of the infraspinatus tendon caused significant superior and posterior translations within the middle ranges of ER for all abduction angles. In addition to superior instability, posterior translation should be considered when selecting or developing surgical techniques for large posterosuperior rotator cuff tears.

Dermal allograft superior capsule reconstruction biomechanics and kinematics

PURPOSE

To investigate the effect of a dermal allograft superior capsule reconstruction (SCR) on kinematics and joint pressure biomechanics immediately after simulated superior irreparable rotator cuff tear.

METHODS

This controlled laboratory study tested 8 fresh-frozen cadaveric shoulders using a custom test frame. Balanced loading configuration centered the humeral head on the glenoid, and unbalanced load created a force pulling the head toward the acromion. Experimental conditions included the intact rotator cuff, irreparable supraspinatus tear (ISST), and dermal allograft SCR. A digital sensor measured glenohumeral and subacromial contact pressure maps, and a microscribe measured the acromion-humeral distance.

RESULTS

Glenohumeral contact pressure of ISST was 175% (295 ± 44 kPa; P = .018) of the intact rotator cuff value (169 ± 10 kPa) at 0° in the balanced condition and 176% (P = .048) of intact at 30°. SCR decreased glenohumeral contact pressure to 110% (185 ± 27 kPa; P = .044) of intact at 0° and to 95% (P = .034) at 30°. Unbalanced ISST contact pressure was 146% (365 ± 23 kPa; P = .009) of intact (250 ± 24 kPa) at 0° and 122% (P = .045) at 60°. SCR decreased contact pressures to 110% (274 ± 21 kPa; P = .039) of intact at 0° and to 89% (P = .003) at 60°. ISST increased superior migration of the humeral head, decreasing the acromion-humeral distance by 3.0 ± 0.6 mm (P = .006) in the unbalanced condition at 0°. SCR increased the acromion-humeral distance to a value similar to that of the intact cuff (P = .003). SCR significantly lowered subacromial pressures in the unbalanced condition.

CONCLUSIONS

In an irreparable supraspinatus tear model, the dermal allograft SCR showed competency in stabilizing the glenohumeral joint, decreasing glenohumeral and subacromial contact pressures, and increasing the acromion-humeral distance.

Arthroscopic superior capsular reconstruction of the shoulder: a narrative review

Irreparable rotator cuff tears (IRCTs) in young and considerably active patients are difficult to treat because it is mostly associated with poor outcome which may lead to a painful and dysfunctional shoulder. Most of the IRCTs are encountered in massive size rotator cuff tears which associated with high failure rate following surgical repair. Thus, the IRCTs was considered challenging for its poor healing rate following repair which may induce the arthritic changes. Since the advent of arthroscopic superior capsular reconstruction (ASCR) of the shoulder in 2013, it has gained its popularity. The procedure has become the most popular option for joint-preserving shoulder surgery for patients with IRCTs. It works by providing a static restraint to the superior humeral head migration to optimize the rotator cuff force couples, hence improving joint kinematics. The acceptance of superior capsular reconstruction has made it rapidly evolving in terms of a wider variety of procedures and broader surgical indications. Despite the enthusiasm and widely acceptance towards the procedure, there are still many queries that exist regarding the best indications, surgical technique particularly graft of choice, the long-term outcome, and the complication and risk of the superior capsular reconstruction (SCR). This narrative review provide the current evidence of SCR in an attempt to provide a state-of-the-art knowledge.

Shoulder biomechanics in normal and selected pathological conditions

The stability of the glenohumeral joint depends on soft tissue stabilizers, bone morphology and dynamic stabilizers such as the rotator cuff and long head of the biceps tendon. Shoulder stabilization techniques include anatomic procedures such as repair of the labrum or restoration of bone loss, but also non-anatomic options such as remplissage or tendon transfers.

Rotator cuff repair should restore the cuff anatomy, reattach the rotator cable and respect the coracoacromial arch whenever possible. Tendon transfer, superior capsular reconstruction or balloon implantation have been proposed for irreparable lesions.

Shoulder rehabilitation should focus on restoring balanced glenohumeral and scapular force couples in order to avoid an upward migration of the humeral head and secondary cuff impingement. The primary goal of cuff repair is to be as anatomic as possible and to create a biomechanically favourable environment for tendon healing.

Cite this article: EFORT Open Rev 2020;5:508-518. DOI: 10.1302/2058-5241.5.200006

Effect of rotator cuff muscle activation on glenohumeral kinematics: A cadaveric study

Healthy shoulder function requires the coordination of the rotator cuff muscles to maintain the humeral head's position in the glenoid. While glenohumeral stability has been studied in various settings, few studies have characterized the effect of dynamic rotator cuff muscle loading on glenohumeral translation during shoulder motion. We hypothesize that dynamic rotator cuff muscle activation decreases joint translation during continuous passive abduction of the humerus in a cadaveric model of scapular plane glenohumeral abduction. The effect of different rotator cuff muscle activity on glenohumeral translation was assessed using a validated shoulder testing system. The Dynamic Load profile is a novel approach, based on musculoskeletal modeling of human subject motion. Passive humeral elevation in the scapular plane was applied via the testing system arm, while the rotator cuff muscles were activated according to the specified force profiles using stepper motors and a proportional control feedback loop. Glenohumeral translation was defined according to the International Society of Biomechanics. The Dynamic load profile minimized superior translation of the humeral head relative to the conventional loading profiles. The total magnitude of translation was not significantly different (0.805) among the loading profiles suggesting that the compressive forces from the rotator cuff primarily alter the direction of humeral head translation, not the magnitude. Rotator cuff muscle loading is an important element of cadaveric shoulder studies that must be considered to accurately simulate glenohumeral motion. A rotator cuff muscle activity profile based on human subject muscle activity reduces superior glenohumeral translation when compared to previous RC loading profiles.