Can objective criteria for poor tolerance of proximal humerus malunion be identified?

BACKGROUND: Malunion of the proximal humerus is common and variably tolerated. Classifications developed for proximal humerus malunion (PHM) rely on standard radiographs, which underestimate bone fragment displacement and lack accuracy. The clinical tolerance of PHM is subjective, and revision surgery is not always necessary. The primary objective of this study was to assess the reproducibility and relevance of four CT angle measurements for objectively quantifying the morphological disharmony caused by PHM in a control population then in a population with PHM. The secondary objectives were to identify angle cut-offs and to assess the correlations between angle values and the clinical tolerance of PHM. HYPOTHESIS: Objective criteria for assessing proximal humerus malunion can be identified using CT scans. MATERIALS AND METHODS: Four angles were chosen to quantify proximal humerus disharmony: the angles between the humeral head and the glenoid in the coronal plane (HGCo) and axial plane (HGAx), the angle of tuberosity divergence in the axial plane (TDAx), and the centrum collum diaphyseal angle (CCD). The reproducibility of measurements of the four angles on computed tomography (CT) views was evaluated in a control population and in 46 patients with PHM. To this end, the reproducibility of reference slice selection was determined and intra- and interobserver reproducibility of the angle measurements was then assessed. Patients with PHM were divided into two groups based on clinical tolerance to allow testing for disharmony parameters associated with poor clinical tolerance, which was defined as functional impairment and surgical revision. RESULTS: Slice selection was found to be reproducible. The Bland-Altman plot indicated that the angle measurements in both the controls and the patients were reproducible within ±2 SDs. Intraclass correlation coefficient values ranged from fair to excellent for all angles in both the controls and the patients. The mean TDAx was higher in the patients than in the controls (72.0° vs. 56.1°, P<0.05) and, within the PHM group, was higher in the subgroup with good vs. poor clinical tolerance (75.8° vs. 69.5°, P<0.05). The CCD angle was greater in the controls than in the patients (129.8° [range, 128.3°-131.3°] vs. 125.9° [range, 122.9°-128.9], respectively) and was significantly greater in the PHM subgroup with good vs poor clinical tolerance (131.4° vs. 122.3°, respectively; P=0.007). The HGCo and HGAx angles were significantly greater in the patients than in the controls (HGCo: 66.6° vs. 52.2°, respectively; HGAx: 17.5° vs. 13.3°, respectively, P=0.55). DISCUSSION: The measurement method described here provides a quantitative assessment of postfracture disharmony based on four angles, the HGCo, HGAx, and TDAx. Measurement of these four angles on CT images was found to have good intra- and interobserver reproducibility. The angle values were significantly greater in the patients with PHM than in the controls. Within the patient group, the subgroup with poor clinical tolerance had smaller values of the TDAx, CCD, and HGAx angles and a greater value of the HGCo angle. LEVEL OF EVIDENCE: IV, retrospective observational study.

Do trapeziometacarpal prosthesis provide better metacarpophalangeal stability than trapeziectomy and ligamentoplasty?

BACKGROUND: No surgical management is better than another regarding functional recovery for trapeziometacarpal joint osteoarthritis. Metacarpophalangeal (MCP) hyperextension, directly due to the shortening of thumb height, appears to be a factor of poor prognosis. HYPOTHESIS: MCP hyperextension can be corrected by implantation of a trapeziometacarpal prosthesis (TMP), as opposed to trapeziectomy and ligamentoplasty (TL), and pinch strength is greater with TMP in this indication. MATERIAL AND METHODS: Sixty-nine patients (41 TMP and 28 TL) were retrospectively evaluated. The following were evaluated: pain, mobility of the metacarpophalangeal joints, palmar grip and pinch strength. Thumb height was measured on radiographs as a post/preoperative ratio. RESULTS: The mean follow-up was 20 months (6-38). The TMP group showed greater reduction of the metacarpophalangeal hyperextension in all hyperextension groups, especially hypertension >30°, compared with TL. The TMP group provided significant greater pinch strength in all the subgroups with preoperative MCP hyperextension. Patient with postoperative MCP hyperextension had a significant lower grip and pinch strength compared with patient without MCP hyperextension. Radiographic analysis showed that thumb height changes were related to the degree of preoperative hyperextension. Postoperatively, patients with postoperative MCP hyperextension had a significant lower thumb height than patient without MCP hyperextension. DISCUSSION: Metacarpophalangeal hyperextension appears to be a factor of poor prognosis for surgical treatment of trapeziometacarpal osteoarthritis when it is not managed. TMP provides better metacarpophalangeal stabilization by restoring thumb length and would avoid surgery on the metacarpophalangeal joint. TMP may be recommended in patients having symptomatic trapeziometacarpal joint osteoarthritis and MCP joint hyperextension. LEVEL OF EVIDENCE: III, retrospective observational case control study.

Linear relationship between lateralization of the bicipital groove and humeral retroversion and its link with the biepicondylar humeral line. Anatomical study of seventy cadaveric humerus scans.

INTRODUCTION: Morphological studies of the humerus have shown that the position of the bicipital groove varies with the individual and the retroversion of the humeral head. Depending on the authors, these two parameters are independent or associated. This study evaluated the relationship between the humeral head axis and its retroversion and the bicipital groove relative to the humeral biepicondylar line. MATERIALS AND METHODS: Seventy cadaveric humeri were scanned to obtain 3D reconstructions. Views of the 3D reconstruction from above showed the bicondylar line, the bicipital groove and the humeral head on a single image. After measuring the humeral retroversion angle and the bicipital groove angle relative to the bicondylar line, we assessed the relationship between these two angles with Pearson's correlation coefficient. RESULTS: Pearson's correlation coefficient indicated a significant linear correlation between the angle of the groove and the angle of humeral retroversion based on the 70 cadaveric humeral bones (the p-value was 7.510-7, the correlation coefficient was -0.5515, and the 95% confidence interval was (-0.6962; -0.3636)). Our study thus demonstrates that the less lateralized the bicipital groove is, the greater the humeral retroversion will be. CONCLUSION: We demonstrated a linear relationship between humeral head retroversion and bicipital groove lateralization. Within our reliability interval, this relationship can be used in clinical practice to evaluate retroversion without resorting to CT of the entire humerus.

Determination of a new computed tomography method for measuring the glenoid version and comparing with a reference method. Radio-anatomical and retrospective study.

PURPOSE: In the literature, there are several techniques for measuring the glenoidal version of the scapula. The superiority of the scannographic measurement over the standard radiologic measures seems evident. The main problems are the evaluation and the reproducibility of these methods, which are dependent on the quality of the CT scan and the orientation of its sections. We pinpoint a simple method of the "scapular triangle", the reliability of which deserves special consideration. The aim of this study is to report a simple and reproducible computed tomography method to measure the glenoidal version. METHODS: Thrity-one shoulder CT scans, performed on patients attending the emergency department of the University Hospital of Dijon between January 2012 and April 2013 for shoulder trauma, were evaluated retrospectively. The CT scan must include the entire body of scapula to allow measurements to be made with both methods: the conventional method of Friedman and our new method of the "scapular triangle". Two independent operators performed inter-observer and intra-observer reproducibility. We compared both techniques with Pearson's test. RESULT: Pearson's test showed a trend line according to a linear correlation between the two methods with a p value of 7.791(-10) and a correlation coefficient of 0.85 with the 95% confidence interval (0.7213; 0.929). CONCLUSION: The method of the "scapular triangle" is easily applicable on most sections of the CT scan of scapula whether or not it takes the whole body. It is more reliable and reproducible and could be used by any radiologist.