Correlation between femoral offset loss and dynamic hip screw cut-out complications after pertrochanteric fractures: a case-control study.

BACKGROUND: Screw-plates disassembly incidence after pertrochanteric fracture (PF) amounts to 1 and 16% among the elderly population. The main occurrence is early cervical screw cut-out. The population at highest risk of disassembly remains difficult to identify. The correlation between femoral offset loss and disassembly occurrence has never been surveyed. OBJECTIVES: A radiological prognosis score for screw plate disassembly was defined to reflect trochanteric impaction (TI); it was based on a femoral offset ratio. STUDY DESIGN AND METHODS: Our single-centre retrospective case-control study surveyed patients suffering from Dynamic Hip Screw (DHS, Synthes®) disassembly following osteosynthesis of non-pathological osteoporotic PF between 2004 and 2014. All cases were categorised by age and gender and paired to three patients in the control group. The primary endpoint was TI measurement, corresponding to offset loss on the operated hip compared to healthy hip offset and expressed as a percentage. The measurement was done on an immediate postoperative X-ray. The secondary endpoints were tip apex distance (TAD) measurement, Ender and AO classifications, as well as postoperative weight-bearing prescription. RESULTS: Twenty-three cases and 69 controls were surveyed. The case group's average age was 87; 70% of the cases were women. The main disassembly occurrence delay was after 27 days. Average TI was 26% within the patients global group and 12% within the control group (p < 10-5). Over a 21% impaction percentage, disassembly occurrence represents a greater risk: OR = 21.95% CI [5.4-104.3], p < 10-5. Ender 3 type fractures were the most frequent indication for surgery within the case group. Average TAD was 20 mm within the case group, and 17 mm within the control group (p = 0.03). The weight-bearing prescription rate was 52% within the control group and 21% within the case group (p = 0.014). 14.5% of the control group had a TI > 21%. CONCLUSIONS: Using the offset ratio tool, TI measurement was associated with a greater risk of DHS disassembly when it was higher than 21%. The exclusive use of a DHS device does not seem optimal for a TI > 21%. Weight-bearing may be prescribed for all the patients with a TI < 21%, provided good implant positioning is secured.

Quantification of clearance and creep in acetabular wear measurements.

BACKGROUND: This study aimed to measure femoral head penetration before occurrence of real wear, and to quantify the portions attributable respectively to clearance and plastic deformations in various acetabular designs. METHODS: We analyzed CT scans from 15 patients at 'day five' after total hip arthroplasty (THA). All patients received Exafit(®) femoral stems and 28 mm heads: 5 patients had cemented Durasul(®) all-PE cups, 5 patients had un-cemented Allofit(®) metal-backed cups, and 5 patients had un-cemented Stafit(®) dual-mobility cups. We also analyzed CT scans of samples of the three head-cup combinations to compare in vivo and in vitro measurements. RESULTS: The mean femoral head penetration measured on 'day five' was lower for all-PE cups (0.196 mm) than for metal-backed cups (0.551 mm) and dual-mobility cups (0.634 mm). CONCLUSIONS: The present study indicates that isolated measurements of femoral head penetration include 0.15-0.46 mm of radial clearance and 0.05-0.27 mm of creep, and confirms that the majority of so-called bedding-in observed in the first post-operative months is not entirely due to wear.

Do Dual-Mobility Cups Reduce the Risk of Dislocation in Total Hip Arthroplasty for Fractured Neck of Femur in Patients Aged Older Than 75 Years?

BACKGROUND: Total hip arthroplasty (THA) for intracapsular neck of femur (NOF) fracture remains debatable as it is associated with higher rates of dislocation, notably in the older part of the population. We hypothesized this risk could be limited using dual-mobility cups (DMCs). METHODS: Eighty-two patients (83 hips) aged older than 75 years underwent DMC-THA using a posterolateral approach for an intracapsular NOF fracture. RESULTS: Clinical data were collected in 45 patients at a mean of 23.8 ± 9.4 months (12.1-42 months). The mortality rates were 19% (16 patients) and 36.5% (30 patients) at 1 year postoperatively and at the last follow-up, respectively. Postoperatively, there were 2 dislocations of the large articulation (4.4%) and one intraprosthetic dislocation (2.2%), all related to technical errors. Functional results were rated at least good in 71% cases, whereas the Parker and Devane scores were stable, indicating optimal restoration of autonomy and physical activity. CONCLUSION: Although technically demanding, DMC-THA may prevent dislocation in intracapsular NOF fracture in elderly patients, while consistently limiting the risk of loss of independence.

Are modern dual mobility cups a valuable option in reducing instability after primary hip arthroplasty, even in younger patients?

Hip instability after total hip replacement has been shown to be a critical cause of failure. The use of dual mobility has been classically restricted to patients "at risk", over 70 years of age. The question rises up about extended indications of so-called "modern" second generation dual mobility cups. This prospective multicenter study reports on first results at 2-5 years of the HA anatomical ADM cup upon two comparative groups of patients under 70 years (112 hips) vs. over 70 years of age (325 hips). No dislocation, migration, tilting, wear, or intra-prosthetic dislocation was recorded within each of the two cohorts. Survivorship for cup failures at this 4-year period was ideal at 100% in the younger patients, and 99.7% in the older group of patients.

Accuracy of glenoid component placement in total shoulder arthroplasty and its effect on clinical and radiological outcome in a retrospective, longitudinal, monocentric open study.

BACKGROUND: The success of Total Shoulder Arthroplasty (TSA) is believed to depend on the restoration of the natural anatomy of the joint and a key development has been the introduction of modular humeral components to more accurately restore the patient's anatomy. However, there are no peer-reviewed studies that have reported the degree of glenoid component mal-position achieved in clinical practice and the clinical outcome of such mal-position. The main purpose of this study was to assess the accuracy of glenoid implant positioning during TSA and to relate it to the radiological (occurrence of radiolucent lines and osteolysis on CT) and clinical outcomes. METHODS: 68 TSAs were assessed with a mean follow-up of 38+/-27 months. The clinical evaluation consisted of measuring the mobility as well as of the Constant Score. The radiological evaluation was performed on CT-scans in which metal artefacts had been eliminated. From the CT-scans radiolucent lines and osteolysis were assessed. The positions of the glenoid and humeral components were also measured from the CT scans. RESULTS: Four position glenoid component parameters were calculated The posterior version (6°±12°; mean ± SD), the superior tilt (12°±17°), the rotation of the implant relative to the scapular plane (3°±14°) and the off-set distance of the centre of the glenoid implant from the scapular plane (6±4 mm). An inferiorly inclined implant was found to be associated with higher levels of radiolucent lines while retroversion and non-neutral rotation were associated with a reduced range of motion. CONCLUSION: this study demonstrates that glenoid implants of anatomic TSA are poorly positioned and that this malposition has a direct effect on the clinical and radiological outcome. Thus, further developments in glenoid implantation techniques are required to enable the surgeon to achieve a desired implant position and outcome.

Measurement of femoral head penetration in polyethylene using a 3-dimensional CT-scan technique.

BACKGROUND: Current techniques for measuring in vivo polyethylene wear suffer from a range of problems, resulting in an unacceptable lack of repeatability and/or insufficient accuracy when they are used to measure the low wear rates associated with new, highly crosslinked polyethylene. We describe an improved CT method for measurement of 3D femoral head penetration in PE acetabular cups that has sufficient accuracy and repeatability to allow assessment of the wear potential of modern implants. METHOD: The accuracy and repeatability of the CT-scan method was determined by blindly repeating measurements on a precisely calibrated 28-mm prosthetic head and by comparing them with direct metrological measurements on 10 acetabular specimens with in vitro wear from machining, and on 8 explanted acetabular specimens with in vivo wear. RESULTS: The intra- and interobserver errors in femoral head diameter were 0.036 mm (SD 0.044) and 0.050 mm (SD 0.022), respectively. CT estimated femoral head penetration in both all-poly and metal-backed acetabular components with accuracy ranging from 0.009 to 0.245 mm (mean 0.080; SD 0.067). INTERPRETATION: We found that the CT method is rapid, is accurate, and has repeatability and ease of availability. Using a slice thickness of 0.0625 mm, this method can detect wear­and also the threshold for the wear rate that causes osteolysis­much earlier than previous methods.

Long-term clinical and MRI results of open repair of the supraspinatus tendon.

UNLABELLED: Open repair of full-thickness tears of the rotator cuff generally improves function, although anatomic failures are not uncommon. We asked whether the presence or absence of an anatomic repair influenced outcomes. We retrospectively analyzed 47 patients (49 shoulders) treated by open proximalized reinsertion of the supraspinatus tendon for chronic retracted detachment. The mean age of the patients at the time of surgery was 59 years. At a minimum 60-month followup (mean, 87 months; range, 60-133 months), we observed an improvement in the age- and gender-adjusted Constant-Murley score from 67% preoperatively to 95% postoperatively and in the pain score. With the last followup MRI, the supraspinatus tendon had reruptured in five patients (12%); the presence of a rerupture did not negatively influence the functional result. Once healing of the repaired tendons was achieved, supraspinatus muscle atrophy never worsened. However, on MRI, fatty infiltration of the supraspinatus, infraspinatus, and subscapularis muscles increased postoperatively despite tendon healing. Radiographic centering of the humeral head was preserved and glenohumeral arthritis remained stable. Functional results were better when the standardized supraspinatus muscle area was greater than 0.5 at the final evaluation. LEVEL OF EVIDENCE: Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

The asymmetric profile of the acetabulum.

Despite the curvaceous profile of the acetabulum, orthopaedic surgeons have continued to implant hemispheric cups since the introduction of total hip arthroplasty. The geometric discrepancies between the natural acetabulum and implant can result in painful iliopsoas impingement attributable to prosthetic overlap at the anterior acetabular ridge over which the iliopsoas tendon extends to leave the pelvis. We expanded on previous in vitro observations of acetabular morphology using a large in vivo sample and quantified the dimensions of the psoas valley. We studied computed tomographic scans of 200 healthy hips from 50 men and 50 women. The acetabular ridges were digitized on three-dimensional bone reconstructions and their coordinates were manipulated in spreadsheets to deduce acetabular diameter, anteversion, and inclination and to plot the rim profile. Our results confirm the acetabular rim is an asymmetric succession of three peaks and three troughs. The psoas valley has the following shape distribution: 79% curved, 11% angular, 10% irregular, and 0% straight. The mean depth of the psoas valley is 5 mm and the latitude of its trough is on average 6 mm below the acetabular equator. The use of side-specific cups that replicate the curvaceous acetabular profile could prevent prosthetic overlap and reduce the incidence of iliopsoas impingement.

Hemispheric cups do not reproduce acetabular rim morphology.

BACKGROUND: Iliopsoas impingement is a recurrent complication following THA, caused by muscle friction against a protrusive prosthetic cup.This study was designed to quantify the dimensional variations in acetabular rim profiles, with particular regard to the iliopubic valley, in order to suggest means to prevent iliopsoas impingement. MATERIAL AND METHODS: 34 cadaver pelvises were analyzed using a hip navigation system. The morphometric data were processed to plot profiles of all acetabular rims with particular regard to the shape and depth of the psoas valley. RESULTS: The acetabular rim is an asymmetric succession of 3 peaks and 3 troughs. The psoas valley is a salient feature in most pelvises and there is only a weak correlation between its depth (mean 3.8 mm, SD 2.0) and acetabular diameter, anteversion, or inclination. INTERPRETATION: It would be difficult to obviate the anterior overlap of the acetabulum using a hemispheric cup, a fortiori in certain morphotypes, without compromising range of motion or risk of dislocation. The solution for prevention of iliopsoas impingement would be to adapt cup design to acetabular anatomy, which may require different implants for the right and left sides, and hence a doubled inventory.

Hip prosthesis infection due to Mycobacterium wolinskyi.

Mycobacterium wolinskyi, first described in 1999, is a rapidly growing mycobacterium related to the Mycobacterium smegmatis group. Only eight cases of infection due to this microorganism have been reported, including three cases of bone infection. Here, we present the first case of a joint prosthesis infection cured with the combination of surgery and prolonged antibiotic therapy. The microorganism was identified by biochemical tests and 16S rRNA and Hsp65 gene sequence analysis.

Bilateral osteonecrosis of the femoral head after pregnancy.

Published cases of non-traumatic avascular necrosis of the femoral head associated with pregnancy are rare. We report a case of a 41-year-old woman who suddenly complained of bilateral hip pain 3 weeks after delivery by Caesarean section. For a problem of sterility, she had been treated with human menopausal gonadotropin and human chorionic gonadotropin (hMG-hCG). Initial radiographs of both hip joints were considered regular. After 4 years' evolution, radiographs of the hip joint showed collapse of both femoral heads. Bilaterally, osteonecrosis of the femoral heads was confirmed by MRI. MRI revealed a band pattern of low signal intensity for both hips on T1- and T2-weighted images. She had no history of steroid therapy or alcohol abuse. Osteonecrosis was related to pretentaine. A bilateral total hip arthroplasty was performed. The literature about avascular necrosis of the femoral head associated with pregnancy in previous cases is reviewed.

Massive tears of the rotator cuff treated with a deltoid flap.

We retrospectively reviewed the charts of 29 patients younger than 65 years at surgery treated with deltoid flap reconstruction for massive postero-superior rotator cuff tears. All tears involved supraspinatus and infraspinatus tendons and were associated with tendon stump retraction to the glenoid rim, a preservable long biceps tendon, and an intact subscapularis tendon. Mean follow-up was 10.5 years. Patient satisfaction rate was 89%. Mean global Constant score improved from 43 to 71.5 points, mean pain score from 6.3 to 13.2, mean anterior flexion from 100 to 157 degrees, and force in elevation from 2.3 to 3 kg. Two thirds of patients had no humeral head migration. Of the 18 patients whose flap was examined by magnetic resonance imaging, 15 had no tear and 12 had a flap signal of muscle intensity; mean flap thickness was 5 mm. Pre-operative factors associated with poorer outcomes were upwards humeral head migration with a subacromial space smaller than 6 mm, presence of glenohumeral osteoarthritis, and supraspinatus amyotrophy greater than 40%. Deltoid flap reconstruction is a valid option in this patient population.

The effect of tourniquet use in total knee arthroplasty.

We conducted a prospective, randomised study on primary total knee replacements to evaluate the effects of tourniquet use on total calculated blood loss using Gross formula, post-operative measured blood loss, operating time, need for blood transfusion, post-operative pain, analgesia requirement and knee flexion. Forty patients were operated on with the use of an arterial tourniquet with pressure of 350 mmHg (group A), and 40 patients without the use of a tourniquet (group B). Total calculated blood loss was significantly increased ( P=0.0165) without the use of a tourniquet. There was no significant difference in measured blood loss or operating time. The median units of blood given were similar in both groups. In spite of autologous transfusions 14% of patients received additional homologous transfusions. At 6 h post-operatively pain was significantly less ( P=0.0458) in group B but was similar at 24 and 48 h. There was no significant difference in analgesia requirement. The mean change in total flexion in group B was significantly better ( P<0.001) at 5 days than in group A, but knee flexion was similar at 10 days and 3 months. Knee arthroplasty operations without the use of a tourniquet cause a greater blood loss but have only small benefits in the early post-operative period.