C. Maynou

Geometrical analysis results of 42 resurfacing shoulder prostheses: A CT scan study

BACKGROUND Shoulder resurfacing arthroplasty was introduced in Scandinavia in the early 1980s then developed by SA Copeland. HYPOTHESIS Resurfacing prostheses restore the normal anatomy of the proximal humerus. Here, our objective was to evaluate humeral resurfacing prosthesis position on radiographs and computed tomography (CT) images. MATERIALS AND METHODS We retrospectively reviewed 42 consecutive cases seen at a single centre between 2004 and 2009. Mean patient age was 65 years. CT was performed routinely before prosthesis implantation and at re-evaluation. The Copeland Mark III(®) (Biomet France SARL, 26903 Valence, France) implant was used in 32 cases and the Aequalis Resurfacing Head(®) (Tornier France, 38334 Saint-Ismier, France) in 10 cases. The post-implantation CT images were used to measure the angle of inclination, medial humeral offset, lateral glenohumeral offset, and version of the implant. RESULTS Mean follow-up was 18 months. Compared to baseline, no significant changes were found at re-evaluation for the angle of inclination or lateral glenohumeral offset. In contrast, medial humeral offset increased by 3.47mm, and excessive anteversion of 4.23° compared to the bicondylar line was noted. DISCUSSION Humeral head resurfacing prostheses restore the overall anatomy of the proximal humeral head. Our CT scan evaluation protocol seems reproducible and enables an evaluation of implant geometry. In our experience, resurfacing arthroplasty restored the native humeral offset. Inadequate retroversion was noted and was probably related to insufficient exposure during surgery. LEVEL OF EVIDENCE Level IV, retrospective study.

Percutaneous CT-guided radiofrequency thermocoagulation in the treatment of osteoid osteoma: A 87 patient series

INTRODUCTION Osteoid osteoma is a painful, benign bone tumor that mainly affects young people. Thermocoagulation is one of the recommended percutaneous treatment methods. This study sought to assess its efficacy and identify risk factors for osteoma recurrence. METHODS Results were analyzed retrospectively for a group of 87 patients treated by thermocoagulation between 2002 and 2011. The recurrence rate was calculated and analyzed relative to patient and tumor characteristics. The treatment efficacy was determined and methods to prevent complications were analyzed. RESULTS The mean follow-up time was 34 months. The average patient age was 23 years. There were seven complications including three patients with delayed wound healing, mainly at tibial sites. The recurrence rate was 10.4%. The success rate for first-line treatment was 89.6% and it was 97.5% for second-line treatment. Analysis of patient characteristics and tumor locations revealed no risk factors for recurrence. CONCLUSION Percutaneous thermocoagulation is a reliable and effective technique that provides fast, long-lasting pain relief. However recurrence can occur even after the nidus is completely resected. These recurrences can be effectively managed by repeat treatment. Recent technical improvements have reduced the risk of thermocoagulation-related complications. LEVEL OF EVIDENCE IV.

Results and limitations of humeral head resurfacing: 105 cases at a mean follow-up of 5 years

BACKGROUND The objective of this study was to assess clinical and computed-tomography (CT) outcomes at least 2 years after humeral head resurfacing to treat concentric gleno-humeral osteoarthritis. HYPOTHESIS Humeral head resurfacing provides similar outcomes to those achieved with stemmed humeral head implants. MATERIALS AND METHODS This single-centre retrospective study included 40 Copeland™ and 65 Aequalis™ humeral resurfacing heads implanted between 2004 and 2012. Mean patient age at diagnosis was 64 years. The diagnoses were osteoarthritis with an intact (68%) or torn (21%) rotator cuff, avascular necrosis (5%), osteoarthritis complicating chronic instability (3%), post-traumatic osteoarthritis (2%), and chronic inflammatory joint disease (1%). Validated clinical scores, radiographs, and CT before surgery and at last follow-up were compared. RESULTS During the mean follow-up of 56 months, complications occurred in 24 implants. Revision surgery with reverse shoulder replacement was required in 18 cases, after a mean of 43.6 months, to treat glenoid wear or a rotator cuff tear. At last follow-up, for the implants that did not require revision surgery, the mean Constant score was 64/100. The implants had a mean varus of 5° and mean retroversion of -13.3°. The mean increase in glenoid cavity depth was 2.4mm. Mean increases in medial and lateral humeral offset were 1.9mm and 2.7mm, respectively. Pre-operative factors significantly associated with failure were rotator cuff tear (P=0.017) and glenoid erosion (P=0.001). DISCUSSION We found a high failure rate related to glenoid wear or progressive rotator-cuff impairment, although CT showed no evidence of implant malposition or overstuffing. Previous studies of stemmed humeral head implants showed better outcomes. Given the low medium-term prosthesis survival rate, we now reserve humeral head resurfacing for concentric osteoarthritis without glenoid erosions or rotator cuff damage. LEVEL OF EVIDENCE IV, retrospective study.

Anatomic and CT scan assessment of Teres Minor: A new index of trophicity

INTRODUCTION The present study reports the development of a CT assessment protocol for Teres Minor (TM) trophicity. HYPOTHESIS Quantitative reproductible Terres Minor assessment on CT estimates the influence of muscle trophicity on the clinical and radiological results of palliative treatment of irreparable rotator cuff tear. MATERIALS AND METHOD An anatomic study of 30 cadaveric shoulders confirmed a constant anatomic relation between Terres Minor and the inferior pole of the glenoid cavity. This landmark was used to develop a novel CT assessment of TM trophicity. RESULTS The CT assessment showed excellent inter- and intra-observer reproductibility. The protocol defines a trophicity index, T2/G (T2 being TM thickness on axial CT slice, and G the maximum glenoid cavity thickness on axial slice), enabling reproductible TM analysis on preoperative arthro-CT. CONCLUSION The study validated the CT protocol, allowing application in pre- and postoperative assessment of irreparable rotator cuff tear. LEVEL OF EVIDENCE Level IV. Retrospective study.