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.

Reproducibility and reliability of subscapularis tendon assessment using CT-arthrography.

BACKGROUND: Computed tomography (CT) coupled with arthrography remains the reference standard for the preoperative evaluation of rotator cuff tears. The objectives of this study were to evaluate intra-observer and inter-observer reproducibilities of CT-arthrographic assessment of the subscapularis tendon and to assess the validity and reliability of this investigation. HYPOTHESIS: CT-arthrography is reliable and reproducible for the preoperative characterisation of subscapularis tendon lesions. MATERIAL AND METHODS: We retrospectively reviewed 67 shoulders with rotator cuff tears in one or more tendons managed by arthroscopy, both to confirm the diagnosis and to allow therapeutic interventions. Each of the 67 preoperative CT-arthrograms was evaluated by three readers, of whom the first two evaluated the images twice at an interval of 30 days. The following were recorded at each reading: partial- or full-thickness tear in one or more rotator cuff tendons, intra-tendinous delamination, tendon stump retraction, and fatty degeneration of the muscles. The position of the long head of biceps tendon was assessed. A statistical analysis was performed using Fleiss' method to compute intra-observer and inter-observer variabilities in CT-arthrography assessment of the subscapularis tendon status. Validity of this assessment was measured by computing the concordance coefficients between CT-arthrography and arthroscopy. RESULTS: Specificity of CT-arthrography was satisfactory for assessing the subscapularis tendon. Sensitivity was low. Significant inter-observer and intra-observer variabilities were documented. The concordance coefficients between CT-arthrography and arthroscopy indicated that major differences were common with all three readers. When assessing the subscapularis tendon by CT-arthrography, all readers experienced difficulties in distinguishing intact tendons, delaminated tendons, and tendons with tears confined to the upper third. DISCUSSION: Although CT-arthrography remains the reference standard for the preoperative investigation of rotator cuff tears, significant variability occurs in assessing the continuity of the subscapularis tendon. Reliability of this assessment is not optimal, as shown by our evaluation of concordance with arthroscopy. Although our data should be interpreted in the light of the investigation and measurement biases present in our study, they suggest that CT-arthrography may fail to provide a valid and reproducible assessment of the subscapularis tendon. The development of magnetic resonance (MR) imaging and MR-arthrography will probably improve the preoperative evaluation of subscapularis tears in the near future. LEVEL OF EVIDENCE: Level III; diagnostic value study.

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.

Sandwich type ceramic liner fracture rate with the Atlas III™ socket: A study of 144 primary total hip replacements at a mean 74 months' follow-up.

INTRODUCTION: Ceramic friction bearings have been proposed as a means of reducing wear in total hip replacement (THR). A "sandwich" composite concept including a ceramic bearing surface has been proposed as simplifying the modularity while matching metal-back cups with a polyethylene liner. It is not precisely known how frequently abnormal noise would occur during functioning of this type of implant, which moreover entails a risk of ceramic liner fracture. HYPOTHESIS: Results with sandwich type ceramic liners are comparable to those with polyethylene liners, without risk of side effects (noise, fracture). PATIENTS AND METHODS: Clinical and radiological results of 144 cementless Atlas III™ cups containing a 28mm-diameter polyethylene-ceramic sandwich type liner coupled to a ceramic Biolox Forte™ head were retrospectively analyzed at a mean 74 months' follow-up. Mean patient age was 59.4 years. Twelve patients were lost to follow-up. Femoral components comprised 61 ESOP™ anatomic stems and 71 BHS™ Corail stems. The radiologic study used Imagika™ software. RESULTS: Global function scores were satisfactory: PMA score, 17.2±1.2 (range, 9 to 18); global Harris score, 93.6±3.1 (49 to 100). Global survivorship was 91.6% (95% CI: 86.34-96.9). Radioclinical analysis found seven liner fractures (5.3%) at a mean 32 months; all were non-traumatic and asymptomatic. Clinical risk factors for liner fracture were overweight, advanced age, dislocation, prosthetic impingement, increased postoperative offset was a radiologic risk factor. DISCUSSION AND CONCLUSION: Despite these satisfactory radioclinical results, matching those for metal-backed implants containing a polyethylene liner, close surveillance is mandatory with this type of composite implant. The high fracture rate with ceramic-polyethylene sandwich type liners and relative lack of symptoms warrant caution in their use. LEVEL OF EVIDENCE: Level IV, retrospective or historic series.