Does hip joint positioning affect maximal voluntary contraction in the gluteus maximus, gluteus medius, tensor fasciae latae and sartorius muscles?

BACKGROUND: Minimally invasive total hip arthroplasty (THA) is presumed to provide functional and clinical benefits, whereas in fact the literature reveals that gait and posturographic parameters following THA do not recover values found in the general population. There is a significant disturbance of postural sway in THA patients, regardless of the surgical approach, although with some differences between approaches compared to controls: the anterior and anterolateral minimally invasive approaches seem to be more disruptive of postural parameters than the posterior approach. Electromyographic (EMG) study of the hip muscles involved in surgery [gluteus maximus (GMax), gluteus medius (GMed), tensor fasciae latae (TFL), and sartorius (S)] could shed light, the relevant literature involves discordant methodologies. We developed a methodology to assess EMG activity during maximal voluntary contraction (MVC) of the GMax, GMed, TFL and sartorius muscles as a reference for normalization. A prospective study aimed to assess whether hip joint positioning and the learning curve on an MVC test affect the EMG signal during a maximal voluntary contraction. HYPOTHESIS: Hip positioning and the learning curve on an MVC test affect EMG signal during MVC of GMax, GMed, TFL and S. METHODS: Thirty young asymptomatic subjects participated in the study. Each performed 8 hip muscle MVCs in various joint positions recorded with surface EMG sensors. Each MVC was performed 3 times in 1 week, with the same schedule every day, controlling for activity levels in the preceding 24h. EMG activity during MVC was expressed as a ratio of EMG activity during unipedal stance. Non-parametric tests were applied. RESULTS: Statistical analysis showed no difference according to hip position for abductors or flexors in assessing EMG signal during MVC over the 3 sessions. Hip abductors showed no difference between abduction in lateral decubitus with hip straight versus hip flexed: GMax (19.8±13.7 vs. 14.5±7.8, P=0.78), GMed (13.4±9.0 vs. 9.9±6.6, P=0.21) and TFL (69.5±61.7 vs. 65.9±51.3, P=0.50). Flexors showed no difference between hip flexion/abduction/lateral rotation performed in supine or sitting position: TFL (70.6±45.9 vs. 61.6±45.8, P=0.22) and S (101.1±67.9 vs. 72.6±44.6, P=0.21). The most effective tests to assess EMG signal during MVC were for the hip abductors: hip abduction performed in lateral decubitus (36.7% for GMax, 76.7% for GMed), and for hip flexors: hip flexion/abduction/lateral rotation performed in supine decubitus (50% for TFL, 76.7% for S). DISCUSSION: The study hypothesis was not confirmed, since hip joint positioning and the learning curve on an MVC test did not affect EMG signal during MVC of GMax, GMed, TFL and S muscles. Therefore, a single session and one specific test is enough to assess MVC in hip abductors (abduction in lateral decubitus) and flexors (hip flexion/abduction/lateral rotation in supine position). This method could be applied to assess muscle function after THA, and particularly to compare different approaches. LEVEL OF EVIDENCE: III, case-matched study.

Short-term comparison of postural effects of three minimally invasive hip approaches in primary total hip arthroplasty: Direct anterior, posterolateral and Röttinger.

INTRODUCTION: There is renewed interest in total hip arthroplasty (THA) with the development of minimally invasive approaches. The anterior and Röttinger approaches are attractive for their anatomical and minimally invasive character, but with no comparative studies in the literature definitely suggesting superiority in terms of quality of functional recovery. We therefore performed a case-control study, assessing: 1) whether the postural parameters of patients operated on with the anterior, Röttinger and posterior minimally invasive approaches were similar to those of asymptomatic subjects, and 2) whether there were any differences in postural parameters between the three approaches at short-term follow-up. HYPOTHESIS: We hypothesized that the anterior and Röttinger approaches are less disruptive of postural parameters than the posterior approach. METHODS: Seventy subjects (44 primary THA patients and 26 asymptomatic control subjects) were enrolled. Operated subjects were divided into 3 experimental groups corresponding to the 3 minimally invasive approaches: posterior (n=14), anterior (n=15) and Röttinger (n=15). Two single-leg stance tests (left followed by right leg stance; 10s per test) were carried out on a stabilometric platform, within 2months after surgery for all THA patients, and for controls. Six significant parameters were selected for statistical analysis: test performance, mediolateral and anteroposterior displacements of the center of pressure (CP), path length, average CP displacement speed, and the ellipse containing 95% of CP projections. Non-parametric statistical tests were used to compare groups. RESULTS: There was no difference between the 3 study groups and the control group according to age, gender, BMI, or side (or between study groups regarding WOMAC score). No significant differences between approaches were found for success on postural tests (P=0.14). Subjects operated on with the anterior or Röttinger approach showed significant differences from asymptomatic subjects for 2 postural parameters: path length (Röttinger P=0.04, anterior P=0.03) and average CP displacement speed (Röttinger P=0.04, anterior P=0.03). Subjects operated on through the posterior approach showed no significant differences from asymptomatic subjects. DISCUSSION: The study hypothesis, that the anterior and Röttinger approaches for hip arthroplasty are less disruptive of postural parameters than the posterior approach, was not confirmed. The anterior and Röttinger approach groups showed higher average CP displacement speed and path length, suggesting that they use up more energy resources to maintain static balance. The posterior approach had the least impact on postural parameters in the first 2 postoperative months. LEVEL OF EVIDENCE: III, case-control study.

Primary unconstrained shoulder arthroplasty in patients with a fixed anterior glenohumeral dislocation.

BACKGROUND: Reports of shoulder arthroplasty for the treatment of fixed glenohumeral dislocation are rare. The purpose of this study was to analyze the results following shoulder arthroplasty in patients with a fixed anterior shoulder dislocation. METHODS: Eleven patients were evaluated at a minimum of twenty-four months after they underwent an arthroplasty for the treatment of a fixed anterior shoulder dislocation. Four patients underwent a total shoulder arthroplasty, and the remainder were treated with a hemiarthroplasty. Four shoulders had osseous reconstruction of the anterior aspect of the glenoid. The patients were evaluated with use of the Constant score, measurement of active anterior elevation and external rotation, the patient's subjective grading of the result, and a radiographic examination. RESULTS: The mean Constant score improved from 21.1 points preoperatively to 46.0 points following the arthroplasty, and the mean active anterior elevation improved from 48.6 degrees to 90.0 degrees . The pain component of the Constant score was the most reliably improved parameter, increasing from a mean of 4.8 points preoperatively to a mean of 11.0 points postoperatively. Eight patients reported that the result was excellent or good, and the remaining three considered it to be fair. We observed seven complications in five patients, including four cases of anterior instability of the shoulder. Two of the four patients treated with a total shoulder replacement were seen to have definite loosening of the glenoid component on follow-up radiographs. CONCLUSIONS: Shoulder arthroplasty in patients with a fixed anterior shoulder dislocation is fraught with difficulties and complications. Although arthroplasty reliably relieved shoulder pain in this population, limited functional results should be expected.

[Shoulder arthroplasty for osteoarthritis after prior surgery for anterior instability: a report of 27 cases]. / Prothèse d'épaule sur omarthrose secondaire à une instabilité antérieure opérée: à propos d'une série de 27 cas.

PURPOSE OF THE STUDY: The purpose of this study was to analyze the natural history of shoulder osteoarthritis secondary to prior surgery for anterior instability, to evaluate clinical and radiological results of shoulder prosthesis, and to compare results with reports in the literature. MATERIAL AND METHODS: Twenty-seven shoulder prostheses (Aequalis) were implanted in patients with osteoarthritis of the shoulder after prior instability surgery. These shoulders were reviewed retrospectively at a mean follow-up of 46 months (range 24-48). Prior surgery had been performed with coracoid block in two-thirds of the shoulders and with soft-tissue procedures in one-third. Twenty-four shoulders had had one instability procedure, several procedures had been performed in three. The Constant score was used to assess clinical status preoperatively and at last follow-up. Male gender predominated (16/27), and mean age at first dislocation was 31.6 years (4 patients experienced their first dislocation after the age of 60 years). The patients had a mean 18.2 dislocations. The natural history of osteoarthritis was long: 24.2 years on the average. Mean age at arthroplasty was 55.8 years. The preoperative images demonstrated an iatrogenic factor in 5 shoulders and constructive osteoarthitis in 24. Posterior glenoid wear was observed in 24% of the cases, fatty degeneration of the subscapularis in 45% and full-thickness tears of the supraspinatus in 4 cases. The anterior scar tissue was released and implants were positioned anatomically in 26 cases. Total arthroplasty was used for 21 shoulders and a humeral prosthesis for 6. RESULTS: There were five complications including three anterior prosthetic instability, all three in patients who were over 60 years of age at their first instability surgery (one of these three patients required revision arthroplasty). Outcome was good or excellent in 56% of the shoulder with a mean weighted Constant score of 83%: mean gain in pain score=8.3 points, in anterior elevation=51 degrees, in external rotation=33.5 degrees. The type of prior instability surgery and preoperative active external rotation had no determining effect on outcome. Factors correlated significantly with outcome were fatty degeneration of the rotator cuff muscles, particularly the subscapularis. DISCUSSION: Osteoarthritis of the shoulder has a long natural history, 26 years in our patients excepting those whose first dislocation occurred after the age of 60 years. Posterior glenoid wear, described by others, was only found in 24% of the shoulders in this series. Surgical dissection and release of anterior scar tissue was difficult. The overall results of arthroplasty were good and were correlated with fatty degeneration of the rotator cuff muscles, particularly the subscapularis, but not with the type of instability surgery. These results were less satisfactory than reported in series of arthroplasty for primary centred osteoarthritis: complications occurred in 18% of the shoulders with three cases of anterior dislocation. Unlike reports of arthroplasty after instability surgery where many of the patients had several operations, overall results in our series were not compromised by a large number of multiple interventions.

Shoulder arthroplasty in patients with a prior anterior shoulder dislocation. Results of a multicenter study.

BACKGROUND: Prior reports of shoulder arthroplasty performed for dislocation-induced arthropathy have included only patients who had had a prior stabilizing procedure. The purpose of this study was to report the results of shoulder arthroplasty in all patients with a prior anterior shoulder dislocation, including both those previously treated operatively and those previously treated nonoperatively. METHODS: Fifty-five shoulders undergoing arthroplasty for arthritis following a prior anterior shoulder dislocation were evaluated. Twenty-seven of the shoulders had undergone a prior anterior stabilization procedure. The measures used to evaluate the shoulders included the Constant score, adjusted Constant score, active mobility, subjective satisfaction, radiographic result, and complications. RESULTS: The shoulders were evaluated at a mean of 45.0 months. The Constant score improved from a mean of 30.8 points preoperatively to a mean of 65.8 points at the time of follow-up. The adjusted Constant score improved from a mean of 38.2% to a mean of 79.8%. Active forward flexion improved from a mean of 82.1 degrees to a mean of 138.9 degrees. Active external rotation improved from a mean of 4.0 degrees to a mean of 38.6 degrees. Fifty patients rated the result as good or excellent. Negative prognosticators included an older age at the time of the initial dislocation and a rotator cuff tear. No significant differences in demographic factors, pre-arthroplasty function, post-arthroplasty function, pre-arthroplasty radiographic findings, post-arthroplasty radiographic findings, complication rate, or reoperation rate were noted between the patients treated with a prior operation for the anterior instability and those treated nonoperatively. CONCLUSIONS: This investigation documented the good results obtainable with shoulder arthroplasty for the treatment of arthritis following anterior shoulder instability. In addition, our findings suggest that capsulorrhaphy-induced arthropathy may be indistinguishable from arthritis following nonoperatively treated anterior shoulder instability.

[Prosthetic hip joint infection caused by Listeria monocytogenes]. / Infection d'une prothèse totale de hanche par Listeria monocytogenes.

The authors report an unusual case of prosthetic hip joint infection caused by Listeria monocytogenes. The patient, an 87-year-old lady who had undergone a right total hip replacement 10 years previously, presented with pain and restriction of hip motion three weeks after an episode of abdominal pain. Aspiration of the joint yielded a dark fluid, from which Listeria Monocytogenes type 4-b was isolated. Blood cultures remained negative. After prolonged antibiotic therapy, symptoms gradually resolved. A few months later, pain recurred with radiological signs of loosening of the femoral component. One-stage revision arthroplasty was performed combined with antibiotic treatment. The patient remains asymptomatic at one year follow-up. Laboratory data and x-ray control are normal. Prosthetic hip joint infection with Listeria monocytogenes is uncommon; few cases have been reported. The literature review shows that prolonged antibiotic therapy alone may be used in patients for whom removal of the prosthesis is not desirable, although revision arthroplasty or prosthesis removal remains necessary in the other cases.