Background and purpose: Dr. H. Resch has with his arthroscopic extracapsular fixation-technique for recurrent post-traumatic anterior instability using resorbable tacs (Suretac) achieved very good results. We have used his technique since October 1994. The results at 2 year follow-up showed a recurrent instability of 11%. Our purpose was to evaluate the long term results 10 years after we first started using this technique. Material and methods: From October 1994 until December 1999 107 patients were operated using the Resch-technique. All had a post-traumatic anterior instability with a Bankart-lesion. At follow-up we were able to get in contact with 86 of the patients (80.3%), 62 male and 24 female. Mean age was 30.7 years (18.2–64.8), and the mean follow-up was 8.2 years (4.2–9.4). Sixty-seven of the 86 patients were clinically examined by an independent observer. Nineteen were not available for clinical examination for various reasons; 14 of them filled out a questionnaire and 5 were interviewed by telephone. Results: Recurrent instability (luxation or subluxation) was found in 13.2% of the patients. Rowe-score showed 90.5% good/excellent, 6.2% fair and 3.1% poor. Mean subjective patient satisfaction was 87 (VAS 0 – 100). Conclusion: A recurrence rate of 13.2% after 4–9 years follow up is comparable with results from other studies using either open or arthroscopic techniques and is considered satisfactory. The patient satisfaction was high and correlates well with the Rowe-score results. The follow-up of 80.3% is lower than we appreciate, but this is a group of young patients which can be a challenge to track down. We are still in the process of tracing the rest of the patients

Objectives. The bony shoulder stability ratio (BSSR) allows for quantification of the bony stabilisers in vivo. We aimed to biomechanically validate the BSSR, determine whether joint incongruence affects the stability ratio (SR) of a shoulder model, and determine the correct parameters (glenoid concavity versus humeral head radius) for calculation of the BSSR in vivo. Methods. Four polyethylene balls (radii: 19.1 mm to 38.1 mm) were used to mould four fitting sockets in four different depths (3.2 mm to 19.1mm). The SR was measured in biomechanical congruent and incongruent experimental series. The experimental SR of a congruent system was compared with the calculated SR based on the BSSR approach. Differences in SR between congruent and incongruent experimental conditions were quantified. Finally, the experimental SR was compared with either calculated SR based on the socket concavity or plastic ball radius. Results. The experimental SR is comparable with the calculated SR (mean difference 10%, . sd. 8%; relative values). The experimental incongruence study observed almost no differences (2%, . sd. 2%). The calculated SR on the basis of the socket concavity radius is superior in predicting the experimental SR (mean difference 10%, . sd. 9%) compared with the calculated SR based on the plastic ball radius (mean difference 42%, . sd. 55%). Conclusion. The present biomechanical investigation confirmed the validity of the BSSR. Incongruence has no significant effect on the SR of a shoulder model. In the event of an incongruent system, the calculation of the BSSR on the basis of the glenoid concavity radius is recommended. Cite this article: L. Ernstbrunner, J-D. Werthel, T. Hatta, A. R. Thoreson, H. Resch, K-N. An, P. Moroder. Biomechanical analysis of the effect of congruence, depth and radius on the stability ratio of a simplistic ‘ball-and-socket’ joint model. Bone Joint Res 2016;5:453–460. DOI: 10.1302/2046-3758.510.BJR-2016-0078.R1

Aims

Post-traumatic periprosthetic acetabular fractures are rare but serious. Few studies carried out on small cohorts have reported them in the literature. The aim of this work is to describe the specific characteristics of post-traumatic periprosthetic acetabular fractures, and the outcome of their surgical treatment in terms of function and complications.

Introduction

Depending on patient's age, risk factors and pretraumatic mobility, a total- or hemiarthroplasty of the hip have become the treatment of choice in femoral neck fractures(1–4). Internal fixation has shown to provide minor results. The majority of these patients are therefore treated by a hemiarthroplasty of the hip. Since the primary goal is to regain the pretraumatic level of mobility as soon as possible(3;5), we sought to investigate, if a minimal invasive anterior approach would be beneficial in regard of perioperative blood loss(6), postoperative pain(7;8) and thus postoperative mobility(9).

Introduction

Metabolic disorders are among known risk factors for tendinopathies or spontaneous tendon ruptures. However, the underlying cellular and molecular mechanisms remain unclear. We have previously shown that human and rat tendon cells produce and secrete insulin upon glucose stimulation. Therefore, we hypothesize that nutritional glucose uptake affects tendon healing in a rat model.

Objectives

The paradoxical migration of the femoral neck element (FNE) superomedially against gravity, with respect to the intramedullary component of the cephalomedullary device, is a poorly understood phenomenon increasingly seen in the management of pertrochanteric hip fractures with the intramedullary nail. The aim of this study was to investigate the role of bidirectional loading on the medial migration phenomenon, based on unique wear patterns seen on scanning electron microscopy of retrieved implants suggestive of FNE toggling.