Purpose: Metal-on-Metal (MOM) hip resurfacing is a popular alternative to conventional hip arthroplasty. The purpose of the present study is to compare patient characteristics and radiographic findings for revision versus non-revision cases treated at a single center with a MOM resurfacing device.

Method: Eighty-nine MOM resurfacing arthroplasties were performed between December 2001 and June 2006. Subjects were assessed for implant revision status, age, gender, weight, operative side, primary diagnosis, femoral head size, and time to revision. Postoperative radiographs were assessed for acetabular cup inclination and femoral stem inclination relative to the femoral neck.

Results: Thirteen of 89 hips (14.6%) have required revision to date with follow-up ranging from 4 (a revision) to 91 months. Female gender, smaller implant size, and a diagnosis of osteonecrosis were all associated with lower device survival. A significant difference in acetabular cup angle was observed between revised and non-revised hips. However, this difference can largely be attributed to two outliers in cup position associated with early migration and the difference became non-significant when these outliers were excluded. No significant difference was found in stem angle between revised and non-revised hips. The revision rate for the first 25 hips was 24% versus 8% for the next 64 hips. Females accounted for 56% of subjects 1–25 and 23% of subjects 26–89. Seven of the 8 failures for the first 25 procedures occurred beyond 4 years follow-up. Only 2 early device failures (< 2 yrs) were identified and both were in the 26–89 subgroup.

Conclusion: Despite representing only 33% of included subjects, females accounted for 62% of revision procedures. An apparent learning curve was identified by a lower device survival proportion for the first 25 hips versus hips 26–89. However, this learning curve was not associated with failures which could be attributed to acetabular or femoral component malpositioning and is likely explained by the higher proportion of females enrolled early in the study. Taken together, we propose the apparent “learning curve” exhibited in our study is not wholly technical in nature but rather influenced by changes in patient selection over time by the operative surgeon.

Introduction: In August 2007, the Department of Health initiative Modernising Medical Careers was implemented. This was a system of reform and development in postgraduate medical education and training. In preparation for the changes, the SAC for T& O outlined a new curriculum. The emphasis of early training, StR years 1 and 2, was to be trauma. We aim to identify how effectively the SAC proposals are being applied, and what difference this makes to the trainees’ operative experience? Furthermore, how do the new posts compare to the historic SHO models?

Methods: A survey carried out by BOTA allowed us to assess post compliance with the SAC recommendations. A compliant job was defined as trauma based for 50% or more of working time. Consent was obtained to evaluate the eLogbooks of trainees in compliant and non-compliant jobs, along with registrars who had previously held traditional SHO grade posts. Overall operative experience over a specified 4 month time period was examined, with focus on routine trauma procedures.

Results: The results of the BOTA and SAC survey revealed that 45% of the new orthopaedic posts were compliant with curriculum guidelines. The eLogbooks of 92 individuals were analysed; 28 historical posts, 34 compliant and 30 non-compliant. The mean total number of recorded entries by trainees in the 4 month period was 73.2 in the historic group, 90.5 in the compliant and 87.3 in the non-compliant job group. The corresponding numbers of trauma operations were 35.7, 48.4 and 41.5.

Conclusions: Operative experience has improved since the introduction of the new curriculum. The new posts are offering more operative and in particular trauma exposure than traditional SHO jobs. If jobs can be restructured such that they all comply with the SAC, educational opportunities in the early years will be maximised.

Since 2003 Trauma and Orthopaedic trainees in the UK and Ireland have routinely submitted data recording their operative experience electronically via the eLog-book. This provides evidence of operative experience of individuals and national comparisons of trainee, trainer, hospital and training programme performance. We have analysed trauma surgery data and established standards for training.

By January 2008 there were over 4 million operations logged. Operations performed and uploaded since 2003 have been included. Each trainee’s work is analysed by ‘year-in-training’. Data on levels of supervision, missed opportunities (where the trainee assisted rather than performed the operation) was analysed. The average number of trauma operations performed annually by trainees was 109, 120, 110, 122, 98 and 84 (total 643) for YIT one (=ST3) to six (=ST8) respectively. There were only 22% of missed opportunities throughout six years of training. A high level of experience is gained in hip fracture surgery (121 operations) and forearm (30), wrist (74) and ankle (47) operative stabilisation over the six years. However, the average number of tibial intra-medullary nails (13), external fixator applications (12) and childrens’ elbow supracondylar fracture procedures (4) performed is low. We are also able to identify trainees performing fewer operations than required during their training (two standard deviations or more below the mean for their YIT). We expect a trainee to have performed at least 255, 383, 473, and 531 trauma operations at the end of YIT three to six respectively.

The eLogbook is a powerful tool which can provide accurate information to support in-depth analysis of trainees, trainers, and training programmes. This analysis has established a baseline which can be used to identify trainees who are falling below the required operative experience.

Purpose of the study: To present our experience in managing Sterno-Clavicular Joint (SCJ) problems. SCJ pain is caused by a number of pathological conditions that include primary, post-infection, and post-traumatic OsteoArthritis (OA), Sterno-Costo-Clavicular Hyperotosis (SCCH) and posttraumatic instability.

Methods: All cases of painful SCJ problems treated surgically by the senior author over the past 20 years have been reviewed.

Results: All operations have been carried out using a “necklace” thyroid type incision. OA in which the pain becomes chronic and disabling, has been treated surgically. Medial clavicle reshaping (2), or hemiarthroplasty with a radial head prosthesis (3), sometimes combined with an interpositional arthroplasty using a GraftJacket is a new technique, developed to obliterate dead space, improve wound cosmesis, and prevent regeneration of the medial clavicle. SCCH is strongly associated with seronegative spondyloarthropathy, and can from part of the SAPHO syndrome (Synovitis, Acne, Pustulosis, Hyperostosis, and Osteitis), Patients with severe excruciating pain and those with restricted motion resulting from complete fusion of the clavicle and sternum may be candidates for surgical treatment. Excision of the medial end of the clavicle (1), the whole clavicle (1) and replacement hemiarthroplasty using a radial head as well as a pectoralis major flap interposition between the first rib and the clavicle (1), is a technique that has not been described previously.

Instability for persistent subluxation or dislocation of the SCJ has been treated with interposition with Graft-Jacket +/− medial clavicle resection (2) or a sterno-mastoid tendon stabilisation (2).

Conclusions: Previous surgical treatment of SCJ problems has been disappointing. Rockwood’s success rate with excision of the medial end of the clavicle alone has been poor (40% good only) – these newer techniques show greater promise.

Objective: Shoulder instability is a common cause of morbidity amongst Professional Rugby Union players. This study explores whether the risk of shoulder dislocation is associated with innate shoulder laxity.

Methodology: We performed a pilot study where we validated techniques we used in the study and subsequently gained Ethics committee approval. The study was a controlled study, in which we visited all the Premiership Rugby Clubs in England. We assessed 169 professional rugby players (mean age 25.1 years, range 18–35) with no history of instability in either shoulder and 46 injured players with one shoulder with clinical shoulder instability symptoms (male, mean age 27.5 years, range 20–33) took part in this study. We assessed shoulder laxity by means of clinical evaluation, questionnaires and ultrasound. Anterior, posterior and inferior translation were measured in both shoulders for healthy players and the uninjured shoulder only for injured players.

Results: We found there is no significant difference between left (anterior: mean 2.92 mm, SD 1.15; posterior: mean 5.10 mm, SD 1.75; inferior: mean 3.08 mm, SD 1.00) and right (anterior: mean 3.07 mm, SD 1.14; posterior: mean 4.87 mm, SD 1.61; inferior: mean 2.91 mm, SD 0.99) shoulder in healthy players (P > 0.05). The comparison between the healthy shoulders (anterior: mean 3.00 mm, SD 1.15; posterior: mean 4.99 mm, SD 1.68; inferior: mean 3.00 mm, SD 1.00) from healthy players and the normal uninjured shoulder (anterior: mean 4.16 mm, SD 1.70; posterior: mean 6.16 mm, SD 3.04; inferior: mean 3.42 mm, SD 1.18) from injured players identified that players with unstable shoulders have a significantly higher shoulder translation in their normal shoulder than healthy players (P < 0.05).

Conclusion: This is the first study looking at laxity and the risk of shoulder dislocations in sportsmen involved in a high contact sport. These results support the hypothesis that rugby players with “lax” shoulders are more likely to sustain a dislocation or subluxation injury to one of these lax shoulders in their sport. We believe pre-season screening and targeted training may play a role in identifying those at risk and may decrease the incidence of dislocations.

Tendons and ligaments are similar in composition but differ in function. Simple anatomical definitions do not reflect the fact individual tendons and ligaments have unique properties due to their adaptation to a specific role. The patellar tendon is a structure of particular clinical interest. A null hypothesis was declared stating that the patellar tendon is not significantly different in terms of matrix composition and collagen fibril diameter to other tendons.

The lateral and medial collateral ligaments (LCL, MCL), anterior and posterior cruciate ligaments (ACL, PCL), together with the long digital extensor, superfi-cial digital extensor and patellar tendons (LDET, SDFT, PT) were harvested from 3 cadaveric ovine hindlimbs. The extracellular matrix was assessed in terms of water, collagen and total sulphated glycosaminoglycan (GAG) content. The organisation of the collagen component was determined by an ultrastructural analysis of collagen fibril diameter distributions using electron microscopy, together with values for the collagen fibril index (CFI) and mass-average diameter (MAD).

There were significant differences between ligaments and tendons. The PT had a bimodal collagen fibril diameter distribution with CFI72.9%, MAD 202nm, water content 53.1%, GAG content 2.3 g/mg and collagen content 73.7%, which was not significantly different from the other tendons.

The results of this study support the null hypothesis suggesting that the patellar tendon is similar to other tendons and demonstrate that tendons have different characteristics to ligaments.

The aim of this work was to define the tensile material properties of the glenoid labrum. Previous SEM studies of the labrum have observed three definitive layers, with a densely packed circumferentially orientated collagen core layer. The glenoid labrum from ten cadaveric shoulders were dissected out and divided into eight equal sections. Each section was cut to produce specimens from the core layer using a microtome and a specifically designed cryo-clamp resulting in uniform specimens with dimensions of 1mm x 1mm x 8mm. All of the tensile testing was performed within a controlled-environment unit of 38°C and 100% relative humidity. Each specimen was precycled to a quasi-static state to alleviate the effects of deep-freezing, prior to final testing. The elastic modulus was calculated for each specimen before and after a 5-minute period of stress relaxation and before failure initiation. The mean age of the specimens was 61 years (range 47–70). Load to failure was 2.7N (1.0–7.0). The mean modulus was 10.2MPa (3.0–22.3) before stress relaxation, 18.0MPa (5.8–36.7) immediately after stress relaxation and 22.3MPa (8.4–66.4) before failure initiation. The 1 and 2 o’clock specimens had lower moduli than the 4 and 5 o’clock specimens (p=0.01). These results can aid in explaining the differing pathologies encountered around the circumference of the labrum. The high moduli at the 4 and 5 o’clock positions may reflect the ability of this portion of the labrum to accommodate forces and thus resist anteroinferior subluxation. The lower moduli at the 1 and 2 o’clock positions suggest that this portion of the labrum is less apt to accommodate tension; this might explain the higher incidence of labral foramen observed in this area and the anatomical variant of the Buford complex.

The skeletal system exhibits functional adaptation. For bone the mechanotransduction mechanisms have been well elucidated; in contrast, the response of tendon to its mechanical environment is much more poorly understood despite tendon disorders being commonly encountered in clinical practice. This study presents a novel approach to developing an isolated tendon system in vivo. This model is used to test the hypothesis that stress-shielding, and subsequent restressing, causes significant biomechanical changes. We propose a control mechanism that governs this process.

A custom-built external fixator was used to functionally isolate the ovine patellar tendon(PT). In group 1 animals(n=5) the right PT was stress-shielded for 6 weeks. This was achieved by drawing the patella towards the tibial tubercle, thus slackening the PT. In group 2 (n=5) the PT was stress-shielded for 6 weeks. The external fixator was then removed and the PT physiologically loaded for a further 6 weeks. In each case, the PT subsequently underwent tensile testing and measurement of length(L) and cross-sectional area(CSA). The untreated left PTs acted as controls (n=10).

6 weeks of stress-shielding significantly decreased material and structural properties of tendon compared to controls (elastic modulus(E) 76.2%, ultimate tensile strength(UTS) 69.3%, stiffness(S) 79.2%, ultimate load(UL) 68.5%, strain energy(SE) 60.7%; p< 0.05). Ultimate strain(US), L and CSA were not significantly changed. 6 weeks of subsequent functional loading (Group 2) caused some improvement in material properties, but greater recovery in structural properties (E 79.8%, UTS 91.8%, S 96.7%, UL 92.7%, SE 96.5%). CSA was significantly greater than Group 1 tendons at 114% of control value.

Previous models of tendon remodelling have relied on either joint immobilization or direct surgical procedures. This model allows close control of the tendon’s mechanical environment whilst allowing normal joint movement and avoiding surgical insult to the tendon itself. The hypothesis that stress-shielding, and subsequent restressing, causes significant biomechanical changes has been upheld. We propose that the biomechanical changes observed are governed by a strain homeostasis feedback mechanism.

The purpose of this study was to determine and compare the effects of radiofrequency ablation and mechanical shaving on tendon using histological and ultrastructural techniques. A single cut using a scalpel blade was used to create a standardised reproducible lesion in 12 freshly harvested ovine infraspinatus tendons. Each lesion was then subjected to either bipolar radiofrequency ablation or mechanical shaving. Specimens were either fixed in formalin and processed for light microscopy or fixed in glutaraldehyde and processed for transmission electron microscopy. Samples of normal and untreated cut tendon were analysed as suitable controls. The radiofrequency treated samples showed an area of coagulative necrosis with an average diameter of 2mm around the lesion. Conversely, the shaved samples showed viable cells up to the edges of the lesion. These findings were supported by ultrastructural appearances, which showed preservation of tendon architecture in shaved samples and widespread denaturation of the tendon matrix with loss of fibrillar structure in the radiofrequency treated samples. Radio-frequency electrical energy and mechanical shaving are often used for resection of soft tissues during arthroscopic reconstructive procedures. The effects of these techniques on tendon are not yet clearly understood. The results of this study indicate that thermal resection of tendon causes an immediate additional 2mm area of tissue necrosis which is not present after mechanical shaving. These findings may have implications for the success of arthroscopic debridement and tendon repair procedures.

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.

Aims: Surgical joint stabilisation can be achieved by capsular plication or thermal shrinkage. We hypothesised that there was no difference in mechanical and morphological properties after reduction of laxity in ligaments treated by either technique.

Methods: 30 skeletally mature female rabbits underwent either ‘thermal’ treatment, or ‘plication’ of their left medial collateral ligament (MCL). After 12 weeks convalescence, MCL complexes were procured from left and contralateral knees to undergo viscoelastic (creep) testing, quantitative transmission electron microscopy (TEM) and immunohistochemistry.

Results: Mean creep strain in both thermal (1.85 +/− 0.32%) and plicated ligaments (1.92 +/− 0.36%) was almost twice that of the control group (1.04 +/− 0.15%), although there was no difference between treatment modalities. However, collagen morphological parameters of all three groups were significantly different (p< 0.001). The thermal ligaments demonstrated predominantly small fibrils, whilst the plicated group displayed an intermediate distribution of heterogeneous fibrils (Fig. I). Immunohistochemistry followed by TEM revealed a random distribution of alpha-smooth muscle actin staining fibroblasts in both thermal and plicated groups.

Conclusion: Susceptibility to creep, and residual deformation after recovery, is similar after thermal shrinkage or plication, although inferior to intact ligaments. However, a different pattern of remodelling was revealed in the treatment groups. The plicated results suggest remodelling on a pre-existing fibrillar scaffold, yet the thermal group demonstrated histomorphometry similar to scar tissue, suggesting de novo synthesis. The absence of contractile myofibroblasts suggests that these cells may play an insignificant role in regulation of matrix tension during healing.

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.

The purpose of this study was to assess the technique of ultrasonographic evaluation of anterior shoulder translation from an anterior approach.

Anterior translation in the right shoulders of 23 volunteers was evaluated using ultrasound with a 10 MHz, 6 cm wide linear transducer. A translatory force of 90 Newtons (N) was used to translate the humeral head in the adduction and internal rotation position (Position 1), while 60 N was used in the more clinically relevant position of 90° abduction and external rotation position (Position 2).

The overall intraobserver coefficients of variation ranged from 0–13% (mean 3.8 ± 2.5%) for examiner 1 and 0.5–20.9% (mean 5.1 ± 3.9%) for examiner 2. The overall interobserver variation ranged from 0–29.8% (mean 9.3 ± 7.3%). The anterior translation in Position 1 ranged from –2.6 to 12.9 mm (mean 2.1 ± 3.1 mm) for examiner I and from −4.1 to 4.7 mm (mean 1.1 ± 2.2 mm) for examiner II. The anterior translation in Position 2 ranged from −3.3 to 3.7 mm (mean 0.3 ± 1.9 mm) for examiner I and from −8.3 mm to 4.5 mm (mean −0.7 ± 2.6 mm) for examiner II. The intraclass correlation coefficients (r) for the measured anterior translation between the 2 examiners for the 2 positions were 0.029 and −0.058 respectively.

The interobserver coefficient of variation remains excessive and there was poor agreement in the measured anterior translation. The finding of negative values in the measured anterior translation despite translatory force raises further concerns about the prospective clinical use of this technique at the present moment.

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.

Surgical joint stabilisation can be achieved by ligamentous plication or thermal shrinkage, and as such, we hypothesized that there is no difference in mechanical and morphological properties after reduction of laxity in ligaments treated by either technique.

Methods: 30 mature female rabbits underwent either ‘thermal’ treatment of their left medial collateral ligament (MCL) using a bipolar radiofrequency probe, or plication with two 4/O non-absorbable sutures following division along its midsubstance and loaded positioning of the free ends. After 12 weeks convalescence, the animals were euthanised and MCL complexes were procured from left and contralateral knees to undergo viscoelastic (creep) testing, quantitative Transmission Electron Microscopy (TEM) and immunohistochemistry. The TEM data was quantified by two data procurement protocols; computational analysis and manual graticule.

Mean creep strain in both thermal (1.85 +/− 0.32%) and plicated ligaments (1.92+/−0.36%) was almost twice that of the control (1.04+/−0.15%), although there was no difference between treatment modalities. Similar findings were seen in the thermal (1.77+/−0.45%), plication (1.85+/−0.40%) and control groups (0.92+/−0.20%) for viscoplastic deformation. However, collagen morphological parameters of all three groups were significantly different (p< 0.001). The thermal ligaments demonstrated predominantly small fibrils, whilst the plicated group displayed an intermediate distribution of heterogenous fibrils. Immunohistochemistry followed by TEM revealed a sparse random distribution of alpha-smooth muscle actin staining fibroblasyts in both thermal and plicated groups. There was an insignificant difference in computational and manual procurement methods (p=0.84).

Susceptibility to creep, and residual deformation after recovery, is similar after thermal shrinkage or plication, although inferior to intact ligaments. However, the plicated results suggest remodeling on a pre-existing fibrillar scaffold, yet the thermal group demonstrated histomorphometry similar to scar tissue, suggesting de novo synthesis. The absence of contractile myofibroblasts suggests that these cells may have an insignificant role in regulation of matrix tension during healing.

The scapulo-humerothoracic rhythm, which can be described by up to 12 spatial variables, is either responsible for, or affected by the genesis of shoulder pathology and trauma, and therefore, imaging the articulations of the shoulder through a global range of motion is desirable in aiding the diagnosis and management of both movement deficiency and osseous lesions.

4 control volunteers were seated between the toroid of the scanner and maximally slewn table on a customised tripod. The subjects were asked to carryout a sequence of defined movements, each over a period of 5 seconds. These included adduction to abduction in the scapular plane, internal rotation to external rotation at 0° and 90° abduction and flexion to extension. An EBCT C300 scanner was used with a multislice sequence imaging protocol to collect 8 transaxial slices per volume by sweeping an x-ray beam sequentially over 4 tungsten target rings and recording x-ray intensity via two fixed detector rings after the reflected beam passes through the body, enabling the acquisition of 20 volumes per movement with minimal radiation exposure. Each slice was post-processed by semi-automatic segmentation using Amira software, and reconstructed to produce three-dimensional reconstructions. Following this, a kinematic description of the joint complex was developed using SIMM, enabling quantification of up to 5 Degrees of Freedom at the Glenohumeral joint.

EBCT provides a quick and efficient method for direct real-time dynamic imaging of the shoulder girdle, although currently crude. As such, we hypothesis the ability of EBCT to image traumatic disruption to shoulder rhythm, and are currently pursuing this work. These reconstructions promise great potential for further clinical experience and quantitative analysis of small translations aided by achievable limited technological refinement of the modality.

This study aimed to quantify the relationship between passive tension of rotator cuff repair and arm position intraoperatively and to examine the effect of the passive tension on gap formation in cadaveric rotator cuff repairs.

Five patients undergoing open surgical reconstruction of the rotator cuff were recruited. The operations were performed by a single surgeon using a standardised technique, which was acromioplasty, minimal debridement, mobilisation of tissue, bone troughs and transosseous suture tunnels.

A Differential Variable Reluctance Transducer (DVRT) was placed at the apex of the debrided tendon. An in situ calibration was performed to relate the output from the DVRT to actual tension in the tendon. The tension generated was recorded as the supraspinatus tendon was advanced into a bone trough and secured.

The relationship between arm position and repair tension was measured, by simultaneously collecting data from the DVRT and a calibrated goniometer. Particular attention was paid to the three standard positions of post-operative immobilisation; full adduction with internal rotation, neutral rotation with a 30° abduction wedge and ninety degrees of abduction.

Five cadaveric shoulders were used for the creation of standardised rotator cuff tears which were then repaired using the technique described above. The difference in tension measured between full adduction and 30° abduction was statically applied for twenty four hours and the gap formation measured.

Repair tension increased with advancement of the supraspinatus tendon into the bone trough. Abduction reduced the repair load, this was observed mainly in the first 30° of abduction. The mean reduction in load by 30° of abduction was 34 N.

Twenty four hours of 34N static loading caused gap formation in each cadaveric rotator cuff repairs, the mean was 9.2 mm.

Rotator cuff repairs tension can be reduced by postoperative immobilisation in 30° abduction. The change in tension with full adduction was caused gap formation in cadaveric rotator cuff repairs.

In vivo loading data for the rotator cuff would be of value to scientists and clinicians interested in the shoulder in the testing of surgical repairs, design of rehabilitation programs and for finite element models.

A technique for insertion and retrieval of the Arthroscopically Insertable Force Probe (AIFP - Microstrain Inc. Burlington, Vermont, USA) from the subscapularis is described was initially established in a cadaveric model. Ethical approval was obtained for AIFP insertion into the subscapularis tendon of volunteers during diagnostic shoulder arthroscopy. An in situ calibration was carried out using a modified arthroscopic grasper ( Smith and Nephew, Huntingdon, UK). After motor effects of interscalene block had worn off dynamic data relating to subscapularis tendon loading was collected. The AIFPs were removed through a port site by traction on an O (3.5 metric) nylon suture without complication.

Maximum loading of the subscapularis tendon was measured during internal rotation from neutral with the arm fully adducted. Forces measured exceeded 200N.

This paper describes a novel technique for the insertion, calibration and retrieval of AIFPs from the rotator cuff. In vivo tendon loading data was obtained. The techniques described may be applied to other structures of interest to orthopaedic surgeons.

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.

Background: Greater tuberosity disuse osteoporosis is a consequence of rotator cuff tear. This is a significant problem as the tendon is implanted into a trough within the greater tuberosity during repair. Failure of the repair is a common complication (up to 50%). We hypothesise that failure in re-implantation is due to deficient bone cell response to mechanical stimulation in the tuberosity.

Methods: In order to establish whether these cells are capable of responding appropriately to mechanical stimuli, the response of bone cells derived from the tuberosity was compared with that of cells derived from the acromion. This was measured in terms of strain related increases in alkaline phosphatase (ALP) activity and nitric oxide (NO) production (which are recognised markers of osteoblast differentiation and their response to mechanical strain). Primary osteoblasts were cultured from samples of acromion and greater tuberosity taken during routine rotator cuff repair (n=10 pairs). The derived cells were:

Placed under cyclic strain at a physiological magnitude for 10 minutes at 1Hz using well established controls. Samples of media were analyzed for changes in NO and the cells were reacted for ALP activity, or:

Results: The results suggest that cells derived from the acromion exhibit significant strain related increases in cellular NO release and in ALP activity, whereas cells derived from the humeral greater tuberosity fail to exhibit any such increases. In marked contrast, cells derived from both sites exhibit increases in ALP activity in response to dexamethasone treatment.

Conclusions: Our results suggest that whilst cells derived from the tuberosity, after rotator cuff tear, respond appropriately to chemical and hormonal stimuli, they are compromised in their ability to respond to mechanical stimulation. Therefore, it is tempting to speculate that such relationships are also evident in vivo and that they underpin re-implantation failures.

Disuse osteoporosis of the greater tuberosity is a consequence of rotator cuff tear. This is a significant problem as the tendon is implanted into a trough within the greater tuberosity during repair. Failure of the repair is a common complication (up to 50%). We hypothesized that failure in re-implantation is due to deficient bone cell response to mechanical stimulation in the tuberosity. In order to establish whether these cells are capable of responding appropriately to mechanical stimuli, the response of bone cells derived from the tuberosity was compared with that of cells derived from the acromion. This was measured in terms of strain related increases in alkaline phosphatase (ALP) activity, nitric oxide (NO) and prostaglandin (PG) production (which are recognised markers of osteoblast differentiation and their response to mechanical strain).

Primary osteoblasts were cultured from samples of acromion and greater tuberosity taken during routine rotator cuff repair (n=5 pairs). The derived cells were placed under cyclic strain at a physiological magnitude for 10 min at 1Hz using well established controls. Samples of media were analysed for changes in NO and PG production and the cells were reacted for ALP. Cells were stimulated with dexamethasone, ascorbic acid and beta-glycerophosphate (established mediators of osteoblast differentiation) then reacted for ALP.

Preliminary results suggest that cells derived from the acromion exhibit significant increases in cellular NO release and in ALP activity, whereas cells derived from the humeral greater tuberosity fail to exhibit any such increases. In marked contrast cells derived from both sites exhibit increases in ALP activity in response to dexamethasone, ascorbic acid and beta-glycerophosphate treatment.

The results suggest that whilst cells derived from the tuberosity after rotator cuff tear respond appropriately to chemical and hormonal stimuli, they are compromised in their ability to respond to mechanical stimulation. It is tempting to speculate that such relationships are also evident in vivo and that they underpin reimplantation failures.

To quantify the variation in strain between the deep and superficial layers of the supraspinatus tendon, ten cadaveric shoulders were tested on a purpose built rig. Differential Variable Reluctance Transducers (DVRTs) were inserted into the superficial and deep aspects of the tendon spanning the critical zone. DVRTs accurately measured linear displacement and from this strain was calculated.

The strain was measured for two aspects of supraspinatus action, abduction from 0 to 120 degrees with a tensile load (100 Newtons) and static load increases at zero abduction (20, 50, 100, 150 and 200 Newtons). After preconditioning, ten sets of results were recorded for each load/position.

The hypothesis, there is a statistically significant difference in strain between the superficial/deep supraspinatus tendon during abduction and with static loading, was tested using a one way ANOVA.

During abduction a statistically significant difference in strain was measured between the layers of the supraspinatus tendon at thirty degrees (p=0.000428) and this increased with further abduction.

Tensile loading increased tendon strain more in the deep layer of the tendon. This was statistically significant at loads greater than 150N (p= 0.007).

The variation in properties between the superficial and deep layers of the supraspinatus tendon has been proposed as a cause of differential strain (1). This study confirms statistically different strains between the superficial and deep tendon layers. It is proposed that the resulting shearing effect initiates intratendinous defects and ultimately tears.

Radio frequency (RF) electrothermal capsulorrhaphy has potential to enhance the results of arthroscopic stabilisation. However, early clinical reports have shown variable results when compared with open stabilisation. Numerous experiments have shown that the mechanical properties of thermally treated tissue are mechanically inferior to normal tissue during the early phase of remodelling. Ultimately, the real issue is how thermally treated tissue compares with tissue shortened by surgical plication, as would occur in an open procedure.

Using a validated technique the tibial insertion of the medial collateral ligament (MCL) of the knee was shifted proximally to induce abnormal laxity in 30 mature NZ White rabbits. Bipolar RF shrinkage was applied to the MCL in 15 rabbits, while in the remainder the MCL was surgically transected and plicated with a nonabsorbable suture. Unlimited mobilisation was permitted until euthanasia at 12 weeks after surgery. Bone-ligament-bone complexes were harvested and underwent low-load (viscoelastic) and high-load (tensile failure) analysis on an Instron mechanical testing apparatus. Specimens from intact MCLs were also collected for polarised light microscopy and transmission electron micrography. Quantitative analysis of collagen fibril morphology was performed on the TEM images.

There were no significant complications postoperatively. In both groups there was evidence of ligament healing and remodelling with a thin layer of scar tissue surrounding the MCL. Preliminary analysis has demonstrated that the cross-sectional area of the thermally treated MCLs was increased compared with the plicated MCLs. Somewhat surprisingly, the plicated group had greater vascularity and cellularity in the healing zone than the thermal group. Although crimp patterns remained disorganised in both groups, the collagen matrix appeared more organised in the thermal group.

These results support the concept that the thermally denatured matrix may act as a scaffold for rapid remodelling of the MCL, resulting in a larger mass of ‘scar’ tissue at the site of shrinkage. Since scar tissue following surgical transection is known to be materially inferior to normal ligament tissue, the increased volume in the thermal group may confer an advantage in structural terms. Mechanical testing is presently underway in our laboratory to determine this issue.

Although the epidemiology and pathomechanics of shoulder injuries in throwing athletes has been wellstudied, less is known about shoulder injuries in other sports where significant loads are carried by the upper limb. We evaluated 90 professional gymnasts who participated in a regular performance schedule during the millennium celebrations in the calendar year 2000. The gymnasts were divided into Group I (n=60) who were selected and trained for 18 months, and Group II (n=30) who were ‘fast-tracked’ through recruitment and training in the final six months before performance.

At the conclusion of the performance year, athletes were assessed using a subjective questionnaire, the SF-12 general health instrument, the Oxford instability questionnaire and the Constant score. They also underwent clinical examination, hypermobility scoring and fatigue testing.

Of those surveyed, 46% complained of pain in one or both shoulders, and the majority of these received nonoperative physical therapy during the year and were able to continue performing. Five patients (6%) had refractory pain, demonstrated signs of hypermobility, abnormal joint translation and positive relocation tests, often in the absence of symptomatic instability. All were in Group II, presented in the final six months of performance and required arthroscopic treatment for complex tears involving the anterior and superior labrum, including the biceps anchor.

These results indicate that the incidence of shoulder injury is very high among professional aerial gymnasts. The underlying cause is likely to be multifactorial in these hypermobile athletes, but the findings are consistent with the concept of cumulative microtrauma to the capsulolabral complex. Acute-on-chronic injury appears to be associated with complex labral pathology which presents with pain rather than with overt instability. Our observations suggest that training and performance schedules should be carefully monitored, incorporating extended preparation and recovery, in order to reduce the risk of shoulder injury. Further work on kinematics of the shoulder during dynamic loading of the weightbearing upper limb is required.