Tanujan Thangarajah

Augmentation of Rotator Cuff Repair With Soft Tissue Scaffolds

Background Tears of the rotator cuff are one of the most common tendon disorders. Treatment often includes surgical repair, but the rate of failure to gain or maintain healing has been reported to be as high as 94%. This has been substantially attributed to the inadequate capacity of tendon to heal once damaged, particularly to bone at the enthesis. A number of strategies have been developed to improve tendon-bone healing, tendon-tendon healing, and tendon regeneration. Scaffolds have received considerable attention for replacement, reconstruction, or reinforcement of tendon defects but may not possess situation-specific or durable mechanical and biological characteristics. Purpose To provide an overview of the biology of tendon-bone healing and the current scaffolds used to augment rotator cuff repairs. Study Design Systematic review; Level of evidence, 4. Methods A preliminary literature search of MEDLINE and Embase databases was performed using the terms rotator cuff scaffolds, rotator cuff augmentation, allografts for rotator cuff repair, xenografts for rotator cuff repair, and synthetic grafts for rotator cuff repair. Results The search identified 438 unique articles. Of these, 214 articles were irrelevant to the topic and were therefore excluded. This left a total of 224 studies that were suitable for analysis. Conclusion A number of novel biomaterials have been developed into biologically and mechanically favorable scaffolds. Few clinical trials have examined their effect on tendon-bone healing in well-designed, long-term follow-up studies with appropriate control groups. While there is still considerable work to be done before scaffolds are introduced into routine clinical practice, there does appear to be a clear indication for their use as an interpositional graft for large and massive retracted rotator cuff tears and when repairing a poor-quality degenerative tendon.

The management of recurrent shoulder instability in patients with epilepsy: a 15-year experience

BACKGROUND The purpose of this study was to review our experience with recurrent shoulder instability in epileptic patients and to discuss factors influencing its management. METHODS A retrospective review was conducted at a single facility. All patients with epilepsy and recurrent shoulder instability were included for study. RESULTS A consecutive series of 33 patients with 49 unstable shoulders presented during a 15-year period. Mean age at the time of the index dislocation was 20 years (range, 9-31). There were 24 patients with 36 anteriorly unstable shoulders, 6 patients with 8 posteriorly unstable shoulders, and 3 patients with 5 multidirectionally unstable shoulders. A large Hill-Sachs lesion was present in 21 shoulders. Glenoid bone loss was seen in 11 cases and involved >25% of the anterior-inferior margin in 6 cases and >50% in 2 cases. Thirty-six shoulders in 31 patients underwent surgery. Ongoing postoperative instability was found in 61% (22 of 36 shoulders) of the anterior group, 38% (3 of 8 shoulders) of the posterior group, and 40% (2 of 5 shoulders) of the multidirectional group. Skeletal reconstruction was found to be associated with a significantly lower rate of recurrence compared with an isolated soft tissue repair (P = .004). Glenohumeral arthrosis was found in 17 patients (22 shoulders) a mean of 12 years (range, 5-20) after the index dislocation. CONCLUSION The presence of bone loss and degenerative changes are the principal factors affecting the specific surgical strategy employed to treat shoulder instability in patients with epilepsy.

Glenohumeral arthrodesis for the treatment of recurrent shoulder instability in epileptic patients

We report our experience with glenohumeral arthrodesis as a salvage procedure for epilepsy-related recurrent shoulder instability. A total of six patients with epilepsy underwent shoulder fusion for recurrent instability and were followed up for a mean of 39 months (12 to 79). The mean age at the time of surgery was 31 years (22 to 38). Arthrodesis was performed after a mean of four previous stabilisation attempts (0 to 11) in all but one patient in whom the procedure was used as a primary treatment. All patients achieved bony union, with a mean time to fusion of 2.8 months (2 to 7). There were no cases of re-dislocation. One revision was undertaken for loosening of the metalwork, and then healed satisfactorily. An increase was noted in the mean subjective shoulder value, which improved from 37 (5 to 50) pre-operatively to 42 (20 to 70) post-operatively although it decreased in two patients. The mean Oxford shoulder instability score improved from 13 pre-operatively (7 to 21) to 24 post-operatively (13 to 36). In our series, glenohumeral arthrodesis eliminated recurrent instability and improved functional outcome. Fusion surgery should therefore be considered in this patient population. However, since the majority of patients are young and active, they should be comprehensively counselled pre-operatively given the functional deficit that results from the procedure.

Management of the unstable shoulder

#### The bottom line The shoulder is the most commonly dislocated joint in the human body. The incidence of shoulder dislocation is increasing.1 Recurrence is common and occurs in as many as 67% of cases.2 Patients often mention a painful, weak arm and a shoulder that readily dislocates with trivial movements. These disabling symptoms can lead to multiple hospital admissions, decreased ability to participate in high level activities, fewer employment opportunities, and a reduction in overall health.3 The “unstable shoulder” has therefore become a relatively common problem seen in primary healthcare, with a reported incidence rate of 2.8%.4 The aim of this review is to provide a simple framework for the clinical assessment, investigation, and treatment of the unstable shoulder for non-specialists and to highlight key patient groups that benefit from early specialist input. #### Sources and selection criteria We searched Medline and the Cochrane library using the terms “shoulder instability”, “shoulder dislocation”, “clinical assessment of shoulder instability”, and “treatment of shoulder instability”. Only articles published in English were included. Data were primarily collated from observational studies, case series, and randomised controlled trials. When a shoulder joint is dislocated by external force (a traumatic dislocation), …

Application of a Demineralized Cortical Bone Matrix and Bone Marrow–Derived Mesenchymal Stem Cells in a Model of Chronic Rotator Cuff Degeneration:

Background: The success of rotator cuff repair is primarily dependent on tendon-bone healing. Failure is common because weak scar tissue replaces the native enthesis, rendering it prone to reruptures. A demineralized bone matrix (DBM) consists of a network of collagen fibers that provide a sustained release of growth factors such as bone morphogenetic proteins. Previous studies have demonstrated that it can regenerate a fibrocartilaginous enthesis. Hypothesis: The use of a DBM and mesenchymal stem cells (MSCs) at the healing enthesis will result in a higher bone mineral density at the tendon insertion and will enhance the regeneration of a morphologically superior enthesis when compared with an acellular human dermal matrix. Study Design: Controlled laboratory study. Methods: Eighteen female Wistar rats underwent unilateral detachment of the supraspinatus tendon. Three weeks later, tendon repair was carried out in animals randomized into 3 groups: group 1 received augmentation of the repair with a cortical allogenic DBM (n = 6); group 2 received augmentation with a nonmeshed, ultrathick, acellular human dermal matrix (n = 6); and group 3 underwent tendon-bone repair without a scaffold (n = 6). All animals received 1 × 106 MSCs delivered in fibrin glue to the repair site. Specimens were retrieved at 6 weeks postoperatively for histological analysis and the evaluation of bone mineral density. Results: All groups demonstrated closure of the tendon-bone gap with a fibrocartilaginous enthesis. Although there were no significant differences in the enthesis maturation and modified Movin scores, repair augmented with a dermal matrix + MSCs exhibited a disorganized enthesis, abnormal collagen fiber arrangement, and greater cellularity compared with other MSC groups. Only repairs augmented with a DBM + MSCs reached a bone mineral density not significantly lower than nonoperated controls. Conclusion: A DBM enhanced with MSCs can augment rotator cuff healing at 6 weeks and restore bone mineral density at the enthesis to its preinjury levels. Clinical Relevance: Biological augmentation of rotator cuff repair with a DBM and MSCs may reduce the incidence of retears, although further studies are required to determine its effectiveness.

Tendon Reattachment to Bone in an Ovine Tendon Defect Model of Retraction Using Allogenic and Xenogenic Demineralised Bone Matrix Incorporated with Mesenchymal Stem Cells

Background Tendon-bone healing following rotator cuff repairs is mainly impaired by poor tissue quality. Demineralised bone matrix promotes healing of the tendon-bone interface but its role in the treatment of tendon tears with retraction has not been investigated. We hypothesized that cortical demineralised bone matrix used with minimally manipulated mesenchymal stem cells will result in improved function and restoration of the tendon-bone interface with no difference between xenogenic and allogenic scaffolds. Materials and Methods In an ovine model, the patellar tendon was detached from the tibial tuberosity and a complete distal tendon transverse defect measuring 1 cm was created. Suture anchors were used to reattach the tendon and xenogenic demineralised bone matrix + minimally manipulated mesenchymal stem cells (n = 5), or allogenic demineralised bone matrix + minimally manipulated mesenchymal stem cells (n = 5) were used to bridge the defect. Graft incorporation into the tendon and its effect on regeneration of the enthesis was assessed using histomorphometry. Force plate analysis was used to assess functional recovery. Results Compared to the xenograft, the allograft was associated with significantly higher functional weight bearing at 6 (P = 0.047), 9 (P = 0.028), and 12 weeks (P = 0.009). In the allogenic group this was accompanied by greater remodeling of the demineralised bone matrix into tendon-like tissue in the region of the defect (p = 0.015), and a more direct type of enthesis characterized by significantly more fibrocartilage (p = 0.039). No failures of tendon-bone healing were noted in either group. Conclusion Demineralised bone matrix used with minimally manipulated mesenchymal stem cells promotes healing of the tendon-bone interface in an ovine model of acute tendon retraction, with superior mechanical and histological results associated with use of an allograft.

The effectiveness of demineralized cortical bone matrix in a chronic rotator cuff tear model

BACKGROUND The purpose of this study was to assess the effect of demineralized bone matrix (DBM) on rotator cuff tendon-bone healing. The hypothesis was that compared with a commercially available dermal matrix scaffold, DBM would result in a higher bone mineral density and regenerate a morphologically superior enthesis in a rat model of chronic rotator cuff degeneration. METHODS Eighteen female Wistar rats underwent unilateral detachment of the supraspinatus tendon. Three weeks later, tendon repair was carried out in animals randomized into 3 groups: group 1 animals were repaired with DBM (n = 6); group 2 received augmentation with the dermal scaffold (n = 6); and group 3 (controls) underwent nonaugmented tendon-bone repair (n = 6). Specimens were retrieved at 6 weeks postoperatively for histologic analysis and evaluation of bone mineral density. RESULTS No failures of tendon-bone healing were noted throughout the study. All groups demonstrated closure of the tendon-bone gap with a fibrocartilaginous interface. Dermal collagen specimens exhibited a disorganized structure with significantly more abnormal collagen fiber arrangement and cellularity than in the DBM-based repairs. Nonaugmented repairs exhibited a significantly higher bone mineral density than in DBM and the dermal collagen specimens and were not significantly different from control limbs that were not operated on. CONCLUSION The application of DBM to a rat model of chronic rotator cuff degeneration did not improve the composition of the healing enthesis compared with nonaugmented controls and a commercially available scaffold. However, perhaps the most important finding of this study was that the control group demonstrated a similar outcome to augmented repairs.

Supraspinatus detachment causes musculotendinous degeneration and a reduction in bone mineral density at the enthesis in a rat model of chronic rotator cuff degeneration

Background To evaluate biological strategies that enhance tendon–bone healing in humans, it is imperative that suitable animal models accurately reproduce the pathological changes observed in the clinical setting following a tear. The purpose of the present study was to investigate rotator cuff degeneration in a rat, as well as assess the development of osteopenia at the enthesis following tendon detachment. Methods Eighteen female Wistar rats underwent unilateral detachment of the supraspinatus tendon. Specimens were retrieved at 4 weeks (n = 6), 6 weeks (n = 6) and 9 weeks (n = 6) postoperatively for histological analysis and peripheral quantitative computer tomography. Results Three weeks following tendon detachment, there was a significant increase in the modified Movin score, characterized by a loss of muscle mass, fatty infiltration, an increase in musculotendinous cellularity, loss of normal collagen fibre structure/arrangement, rounded tenocyte nuclei and an increase in the number of vascular bundles. This was accompanied by a reduction in bone mineral density at the tendon insertion site. After 3 weeks however, these changes were less prominent. Conclusions The rotator cuff tendon-muscle-bone unit in a rat model 3 weeks after detachment of supraspinatus represents a valid model for investigating rotator cuff degeneration.

Constrained fixed-fulcrum reverse shoulder arthroplasty improves functional outcome in epileptic patients with recurrent shoulder instability

AIM To report the results of fixed-fulcrum fully constrained reverse shoulder arthroplasty for the treatment of recurrent shoulder instability in patients with epilepsy. METHODS A retrospective review was conducted at a single facility. Cases were identified using a computerized database and all clinic notes and operative reports were reviewed. All patients with epilepsy and recurrent shoulder instability were included for study. Between July 2003 and August 2011 five shoulders in five consecutive patients with epilepsy underwent fixed-fulcrum fully constrained reverse shoulder arthroplasty for recurrent anterior shoulder instability. The mean duration of epilepsy in the cohort was 21 years (range, 5-51) and all patients suffered from grand mal seizures. RESULTS Mean age at the time of surgery was 47 years (range, 32-64). The cohort consisted of four males and one female. Mean follow-up was 4.7 years (range, 4.3-5 years). There were no further episodes of instability, and no further stabilisation or revision procedures were performed. The mean Oxford shoulder instability score improved from 8 preoperatively (range, 5-15) to 30 postoperatively (range, 16-37) (P = 0.015) and the mean subjective shoulder value improved from 20 (range, 0-50) preoperatively to 60 (range, 50-70) postoperatively (P = 0.016). Mean active forward elevation improved from 71° preoperatively (range, 45°-130°) to 100° postoperatively (range, 80°-90°) and mean active external rotation improved from 15° preoperatively (range, 0°-30°) to 40° (20°-70°) postoperatively. No cases of scapular notching or loosening were noted. CONCLUSION Fixed-fulcrum fully constrained reverse shoulder arthroplasty should be considered for the treatment of recurrent shoulder instability in patients with epilepsy.

Management of recurrent shoulder instability in patients with epilepsy

Epileptic seizures can cause dislocation of the shoulder. Recurrent instability is common and occurs soon after the first dislocation. Significant bone loss from the humeral head and glenoid is thought to be responsible for this, and therefore the majority of surgical approaches focus on bone augmentation of the glenohumeral joint. Understanding of the current management strategies and the anatomic lesions associated with seizure-related shoulder instability will guide clinical decision-making. The purpose of this article was to review the pathoanatomy, treatment options, and clinical outcomes of seizure-related shoulder instability.