Background

Re-attachment of tendon to bone is challenging with surgical repair failing in up to 90% of cases. Poor biological healing is common and characterised by the formation of weak scar tissue. Previous work has demonstrated that decellularised allogenic demineralised bone matrix (DBM) regenerates a physiologic enthesis. Xenografts offer a more cost-effective option but concerns over their immunogenicity have been raised. We hypothesised that augmentation of a healing tendon-bone interface with DBM incorporated with autologous mesenchymal stem cells (MSCs) would result in improved function, and restoration of the native enthesis, with no difference between xenogenic and allogenic scaffolds.

Summary

Our study shows that a tendon rupture can be successfully augmented with Demineralised Cortical Bone (DCB) giving initial appropriate mechanical strength suitable for in vivo use providing the biological reactions to the graft are favourable.

Repair of tendon injuries aims to restore length, mechanical strength and function. We hypothesise that Demineralised Cortical Bone (DCB) present in biological tendon environment will result in remodelling of the DCB into ligament tissue. A cadaveric study was carried out to optimize the technique. The distal 1cm of the patellar tendon was excised and DCB was used to bridge the defect. 4 models were examined, Model-1: one anchor, Model-2: 2 anchors, Model-3: 2 anchors with double looped off-loading thread, Model-4: 2 anchors with 3 threads off-loading loop. 6 mature sheep undergone surgical resection of the distal 1cm of the right patellar tendon. Repair was done using DCB with 2 anchors. Immediate mobilisation was allowed, animals were sacrificed at 12 weeks. Force plate assessments were done at weeks 3, 6, 9 and 12. Radiographs were taken and pQCT scan was done prior to histological analysis. In the cadaveric study, the median failure force for the 4 models; 250N, 290N, 767N and 934N respectively. In the animal study, none of the specimens showed evidence of ossification of the DCB. One animal failed to show satisfactory progress, X-rays showed patella alta, on specimen retrieval there was no damage to the DCB and sutures and no evidence of anchor pullout. Functional weight bearing was 79% at week12. Histological analysis proved remodelling of the collagen leading to ligamentisation of the DCB. Results prove that DCB can be used as biological tendon substitute, combined with the use of suture bone anchor early mobilisation can be achieved.

Treatment of tendon and ligament injuries remains challenging; the aim is to find a biocompatible substance with mechanical and structural properties that replicate those of normal tendon and ligament. We examined the mechanical properties of Demineralised Cortical Bone (DCB) after gamma irradiation (GI) and freeze drying (FD). We also used different techniques for repairing bone-tendon-bone with DCB in order to measure the mechanical performance of the construct. DCB specimens were allocated into 4 groups; FD, GI, combination of both or none. The maximum tensile forces and stresses were measured. 4 cadaveric models of repair of 1cm patellar tendon defect using DCB were designed; model-1 using one bone anchor, Model-2 using 2 bone anchors, Model-3 off-loading by continuous thread looped twice through bony tunnels, Model-4 off-loading with 3 hand braided threads. Force to failure and mode were recorded for each sample. FD groups results were statistically higher (p=<0.05) compared to non-FD groups, while there was no statistical difference between GI and non-GI groups. The median failure force for model-1: 250N, model-2: 290N, model-3: 767N and model-4: 934N. There was no statistical significance between model-1 and model-2 (p=0.249), however statistical significance was found between other models (p=<0.006). GI has no significant effect on mechanical strength of the CDB while FD may have positive effect on its mechanical strength. Our study shows that a tendon rupture can be successfully augmented with CDB giving initial appropriate mechanical strength suitable for in vivo use providing the biological reactions to the graft are favourable.

Introduction: Osteoarthritis (OA) is a common disease that affects 80% of the population over the age of 65 years. Little is known about the pathogenesis of OA. It is characterised by degradation of articular cartilage. Proteomic studies undertaken at our Institute using 2D gel electrophoresis and mass spectrometry identified about 30 proteins secreted by articular cartilage. Two whose synthesis was upregulated in OA were collagen II and activin A. This study quantified activin A production by human cartilage and investigated factors that may stimulate this.

Methods: Cartilage from normal (n=4) and OA (n=8) specimens were obtained from patients undergoing surgery and explants were cultured. Activin A secretion over five hours was measured in the culture medium by ELISA.

In order to determine factors that stimulate activin A production, chondrocytes were isolated from human cartilage and stimulated with various cytokines. RT-PCR methods were used to measure activin mRNA production and the culture medium was assayed for activin protein. Cartilage explants were also stimulated and activin protein levels were measured.

Results: OA cartilage produced higher amounts of activin A (range 34.9 – 97.1 ng/ml) compared to normal (range 9.4 – 15.6 ng/ml). IL-1, TGF-β and bFGF stimulated activin A mRNA and protein production by isolated chondrocytes. TGF-β and bFGF also stimulated activin production by explants, whereas IL-1 did not. This suggests that environment may determine cellular responses.

Conclusions: Activin A has not previously been described in articular cartilage. It is a homodimer of two inhibin β chains and is a member of the TGF-β superfamily originally purified from ovarian follicular fluid. Activin can induce mesenchymal cell differentiation e.g. chondrogenesis and has been shown to play a role in wound healing. To our knowledge we have shown for the first time that activin is produced by chondrocytes in response to various stimuli and that it may play a regulatory role in osteoarthritis.

Introduction and Aims: To evaluate the technique of the knotless suture anchor for the treatment of anterior shoulder instability.

Method: 109 patients were reviewed. Each patient underwent a standardised procedure by the same surgeon under a regional interscalene block and/or general anaesthesia. An average of three anchors were placed in the 3, 4 and 5 o’clock positions. 40 patients had additional thermal shrinkage to reduce excess capsular volume. Each patient was assessed using the Constant, Rowe and Walch-Duplay scores.

Results: Follow-up period was 18 months, with an average of two years. The average operating time was one hour. Four patients (3.6%) redislocated following surgery. Two of these patients had a glenoid bone deficiency of > 20% and associated full thickness rotator cuff tears, one had an associated humeral avulsion of the glenohumeral ligament (HAGL) lesion, which was not repaired arthroscopically, and one had returned to contact sports as early as 12 weeks after surgery. Three patients had single episodes of subluxations that have not required revision. The average Rowe score was 90.8, average Constant score was 89.9 and the average Walch-Duplay score was 81.4.

Conclusion: Early results indicate that capsulolabral reconstruction using the knotless suture anchor is an effective procedure in the treatment of post-traumatic anterior shoulder instability. The incorporation of a south to north capsular shift technique during labral reattachment reduces the necessity of additional thermal to reduce redundant capsular volume. Relative contraindications of this technique include; presence of a HAGL lesion, and anterior glenoid bone deficiency. The procedure may be performed as a day case under regional anaesthesia, has a high index of patient satisfaction and is an acceptable alternative to open surgery.

Purpose: Many different rotator cuff repairs have been advocated in previous publications without experimental evidence. Our aim was to mechanically test the static tensile properties and cyclical loading to failure of a single row lateral anchor repair and a double row medial and lateral anchor repair.

Method: Fresh frozen cadaveric shoulders were mounted on a rig and a mini-open deltoid split used to visualise the supraspinatus. A standardised full thickness incision of 2 cms was made with a scalpel across the supraspinatus tendon. After the deltoid was repaired and specimens randomised, an arthroscopic rotator cuff repair was performed by the two senior authors in which the medial border of the tear was apposed to the lateral border using either a double or single row technique with a ‘Twinfix AB’ suture anchor. Once the repair had been performed, the gross specimens were dissected down to the rotator cuff musculature and the repair inspected. Those with associated cuff pathology were excluded from the experiment. Specimens were then mounted on a custom made rig to statically load each tendon simulating physiological loading of a repaired cuff defect in a post-operative 300 abducted position. The increase in tear size was then measured against time for 1 hour or to a point at which the mean tendon gap formation exceeded 5mm. Each specimen was then transferred to an Instron tensile testing machine to cyclically load to failure the supraspinatus musculotendinous unit. Each specimen was freeze clamped proximally in a specially designed clamp, whilst the humeral shaft was mounted at an angle of 300 of abduction.

Results: The two groups had a distinct difference in tensile properties with the single row fixation developing a 5mm gap in under 30 minutes. After 1 hour, the gap formed in the double row specimens was less than 5mm. In cyclical loading, the single row failed at a lower load compared with the double row. In some double row specimens the tendon failed mid substance above 250N, rather than at the anchor-suture or suture-tendon interface.

Conclusions: Our results suggest that the double row mattress technique has superior loading properties when tested with a simulated physiological load comparative to the normal post-operative setting.

Purpose: Revision surgery after failed open stabilisation can be difficult and challenging. Arthroscopy has been utilised for assessment and preoperative planning, but there are few reports of arthroscopic stabilisation as the definitive revision procedure.

Methods: We reviewed our experience of 12 cases requiring revision, including one originally stabilised at our own institution. There were 9 males and 3 females, with an average age of 27 years assessed at an average of 18 months (range 6–46 months) following arthroscopic revision. Patients were scored using the SF-12, simple shoulder test, and Walch-Duplay outcome measures.

Results: The cases were revised arthroscopically from 6 months to 11 years after the open procedure, which included Bankart repairs (with and without suture anchors), capsular shifts and Putti-Platt procedures. Eight cases were successfully revised for symptomatic recurrent anterior instability, and in all capsulolabral reconstruction was carried out using a knotless anchor technique. In two cases secondary posterior instability was managed either by posterior labral repair or by balancing anterior release. In two cases disabling postsurgical stiffness was managed by arthroscopic anterior release with improvement in functional range of motion.

Summary: Open surgical stabilisation can be complicated by recurrent instability or stiffness, or may be followed by further trauma in this active athletic population. Arthroscopy enables detailed and more thorough diagnosis of the reason for failure. These early results demonstrate that arthroscopic revision is safe and feasible, facilitates a range of intra-articular surgical options and provides outcomes that may be comparable with open revision.

Background: Arthroscopic stabilisation surgery for the shoulder remains a controversial choice of treatment for post traumatic anterior instability. We present the results of a consecutive initial series of 50 patients who were stabilised using a knotless labral repair technique. Methods: The study group included 41 men and 9 women with an average age of 26 years. 58% were affected on the dominant side. The average duration of preoperative syptoms was 3.8 years. 72% of patients had dislocations, whilst the remainder experienced subluxations. Each patient underwent a standardised procedure by the same surgeon with a regional interscalene block and/or general anaesthesia. Anchors were placed in the 3, 4 and 5 o’clock positions. Each patient was assessed using the Constant, Rowe and Walch-Duplay scores at an average of 18 months follow up (range 12–36 months). Results: At review 95% of shoulders remained stable. One patient had a true dislocation 6 months post surgery. One patient experienced a subluxation following a direct whilst skiing. 6 patients remained apprehensive. 3 patients had minor restriction of external rotation. The average Rowe score was 90.8, average Constant score was 89.9 and the average Walch-Duplay score was 81.4Conclusions: Early results indicate that capsulolabral reconstruction using the knotless suture anchor combined with a south to north capsular shift is an effective procedure in the treatment of post-traumatic anterior shoulder instability. This procedure may be performed as a day case under regional anaesthesia and is associated with a high index of patient satisfaction with a return to sporting activities.

Arthroscopic stabilisation of the shoulder is a technically-demanding and developing technique, and the reported results have yet to match those for open surgery. We present a consecutive initial series of 55 patients with post-traumatic recurrent anteroinferior instability managed since September 1999 using a titanium knotless suture anchor. Patients were reviewed from 12–33 months postoperatively and assessed using the Rowe, Walch-Duplay and Constant scores. Following mobilisation of the capsulolabral complex, labral reconstruction was achieved using a two-portal technique and an average of three anchors placed on the glenoid articular rim. In 13 cases, additional electrothermal shrinkage was required to reduce capsular redundancy in the anterior and inferior recesses following labral repair, although 11 of these were in the first 18 months. Incorporation of a south-to-north capsular shift has reduced the need for supplementary shrinkage. Complications have included one instance of anchor migration requiring open retrieval and two documented episodes of recurrent instability, although these occurred in patients having surgery within the first six months after the introduction of this technique. Based on our initial experience, we believe that arthroscopic labral repair is a viable alternative to open Bankart repair and have now expanded the indications to include patients with primary dislocation, those participating in gymnastic and contact/collision sports, and revision cases with failed open repairs.