HIP International

Gluteal tendon tears are one of the many pathologies causing pain around the greater trochanter that are often labelled as trochanteric bursitis. We systematically reviewed the peer-reviewed literature to establish the accuracy of magnetic resonance imaging and ultrasonography in the diagnosis of gluteal tendon tears in patients with persistent lateral hip pain or Greater Trochanteric Pain Syndrome (GTPS).

7 studies met the inclusion criteria, comparing either imaging modality with a reference standard of surgical findings. Included studies were assessed for methodological quality using the QUADAS checklist. MRI had sensitivity of 33–100%, specificity of 92–100%, positive predictive value of 71–100% and negative predictive value of 50%. False-positives were common. High signal located superior to the trochanter had a stronger association with tears. Ultrasonography had a sensitivity of 79–100% and positive predictive value of 95–100%.

The amount and quality of literature on the subject is limited and further well-designed studies are required to establish the optimum diagnostic strategy in this condition. Ultrasonography may prove to be the investigation of choice, despite requiring a skilled practitioner. The orthopaedic surgeon should liaise with an experienced musculoskeletal radiologist to best investigate and diagnose gluteal tendon tears in the clinical picture of GTPS.

Understanding acetabular cup orientation is important in all aspects of total hip arthroplasty including preoperative planning, intraoperative positioning, and postoperative analysis. New concepts in ideal cup orientation such as ‘combined anteversion’ have emerged. Using computer navigation and three-dimensional imaging, the potential for accuracy and precision of implantation have improved. Nevertheless, the varying manner in which the terms “anteversion” and “abduction” are often used in the literature is indicative of a nebulous understanding of the complex spatial anatomy of acetabular cup orientation.

The authors report a series of 11 patients treated surgically by trochanteroplasty for septic arthritis of the hip at our institution from 1974 to 2010.

Trochanteroplasty was indicated due to the absence of a valid alternative, and because it does not rule out the option of total hip arthroplasty at a later stage.

We attempted to quantify the effects of isolated femoral derotation osteotomies using clinical evaluation and gait analysis (kinematics and kinetics) in patients with cerebral palsy (CP). Twelve children with CP were evaluated before and 10 months after isolated femoral derotation osteotomy, and 15 healthy children were evaluated as controls.

There were significant improvements on clinical examination. A better position of the hip and ankle in the transverse plane was evident and significant changes occurred in terms of hip and ankle kinetics after surgery.

Improvements in kinematics and hip and ankle power are very important biomechanically. The correction of lever arm dysfunction and more physiological hip and ankle power generation result in an improvement in terms of energy consumption, leading to a more functional and economic gait pattern.

Only a limited number of reports of total hip replacements (THRs) in patients with Gaucher disease (GD) have been published, with the majority showing high rates of early aseptic loosening as well as an increased number of peri-operative complications.

We present a series of twelve THRs in nine affected patients, with a mean age of 39 years at the time of surgery (median 37 years; range 27–60 years). We examine the medium- to long-term results and present the outcome scores, survival, and assess the effect of enzyme replacement therapy (ERT).

Four hips (33.3%) required revision for aseptic loosening at a mean time of 11.5 years. There was no significant difference in survival between the group on ERT at the time of surgery and group not on ERT. Those on ERT did, however, have fewer peri-operative complications and there was a trend to better outcome scores. Five of the 12 THRs were performed when the diagnosis of GD was unknown and all of these had early complications.

Our results show better survival of THRs in patients with GD than previously thought. The use of ERT pre-operatively did not have an effect on survival, nor outcome scores, but did reduce the peri-operative complication rate. Those not on ERT at the time of surgery were commenced on it at some point in their treatment (at an average of 8.6 years following THR) and we believe the use of ERT, at any time in the treatment, could have contributed to the improved survival seen in our series compared to historical results in the literature.

Core decompression and grafting has been shown to relieve pain and possibly prevent disease progression in patients with symptomatic osteonecrosis (ON) of the hip. However, there is a lack of evidence regarding the management of the asymptomatic hip with femoral head ON. The purpose of this study was to evaluate the outcome of core decompression in the asymptomatic hip with ON. We prospectively followed 37 consecutive patients with MRI confirmed ON of the hips that underwent simultaneous bilateral core decompression and bone grafting. Prior to surgery, only one of the hips was symptomatic, and the main indication for surgical decompression of the asymptomatic side was to prevent disease progression. No hip on the asymptomatic side was staged greater than Steinberg IIB classification. Serial radiographs were followed for evidence of disease progression. Six patients were lost to follow-up prior to two years. The remaining 31 patients were followed for an average of 32.6 months. There were 20 men and 11 women with an average age of 40.6 years. Ten patients with asymptomatic hips at the time of surgical decompression had disease progression requiring THA. The mean time to arthroplasty in this group was 15.1 months. Meanwhile, 13 symptomatic hips at the initial surgery progressed to THA at an average of 12.9 months following core decompression. The proportion of hips requiring conversion to THA was similar between the two groups (p=0.30), and the rate of progression to THA was not significantly faster compared to patients with symptomatic hips who subsequently required THA (p=0.18). Core decompression for asymptomatic ON of the femoral head is unpredictable. Based on our results, asymptomatic ON lesions particularly in the setting of bilateral disease should be closely observed and surgery reserved for when symptoms arise.

In the United Kingdom, national guidelines have stated that patients undergoing elective hip surgery are at increased risk for venous thromboembolic events (VTE) following surgery and have recommended thromboprophylaxis for 28–35 days (1, 2). Studies of direct thrombin inhibitors have hitherto concentrated on major bleeding. We prospectively assessed wound discharge in patients who underwent hip arthroplasty and who received oral dabigatran postoperatively between March 2010 and April 2010 (n=56). We compared these results to a retrospective matched group of patients who underwent similar operations six months earlier, at which time all patients were given subcutaneous dalteparin routinely postoperatively until discharge, and then discharged home on 150mg aspirin daily for 6 weeks (n=67). Wound discharge after 5 days was significantly higher in the patients taking dabigatran (32% dabigatran n=18, 10% dalteparin n=17, p=0.003) and our rate of delayed discharges due to wound discharge significantly increased from 7% in the dalteparin group (n=5) to 27% for dabigatran (n=15, p=0.004). Patients who received dabigatran were more than five times as likely to return to theatre with a wound complication compared with those who received dalteparin (7% dabigatran n=4, vs. 1% dalteparin n=1), but this was not statistically significant (p=0.18). We now administer dalteparin until the wound is dry and then start dabigatran. Our study demonstrates the need for further clinical studies regarding wound discharge and direct thrombin inhibitors.

We conducted a retrospective study of the occurrence of deep venous thrombosis (DVT) following mini-posterior total hip arthroplasty (THA) in Japanese patients. From May 2004 to December 2009 mini-posterior THA was performed on 1659 cases, of whom 603 cases didn't receive anticoagulants (Group 1), 547 cases received 2.5 mg percutaneous injection of fondaparinux (a factor Xa inhibitor) daily for 7 days starting the day after surgery (Group 2), and 509 cases received 2000IU percutaneous injection of enoxaparin (low-molecular-weight heparin) twice daily for 7 days starting the day after surgery (Group 3). The baseline characteristics were very similar in each group. All patients started walking the day after surgery, were advised to wear graduated compression stockings for six weeks after the operation, and used a foot pump for 3 hours a day postoperatively for several days. A week after surgery Duplex ultrasound with colour-flow Doppler imaging of the lower extremities was performed. The occurrence of DVT was significantly different between Groups 1, 2, and 3 (p<0.001): 57 cases (9.5%), 4 cases (0.7%), and 0 cases (0%), respectively. No patients of any group had clinically detected pulmonary emboli. In this study we showed that adding anticoagulants with foot pumps further reduced the incidence of DVT, which seldom occurs following less invasive mini-posterior THA combined with early mobilisation, foot pumps, and anticoagulants.

We investigated the accuracy of implant positioning during total hip arthroplasty (THA) through a minimally invasive approach in relation to body mass index (BMI) and gender by assessing 48 patients. Functional and radiological parameters were evaluated.

BMI positively correlated with operation time (p=0.04), but BMI and gender had no influence on implant positioning. The Harris hip score (HHS) increased significantly (46.5±11.8 preoperatively, 92.1±9.7 postoperatively, p<0.0001).

The surgical approach described resulted in reproducibility of implant positioning independent of influence by BMI or gender.

The effect of obesity on the long-term survival of total hip arthroplasty remains under discussion. Reviewing meta-analyses of large cohort studies a high body mass index has been correlated with a higher incidence of complications but not univocally with a lower implant survival rate. It has been suggested that body weight rather than body mass index might be a better parameter to evaluate prosthesis outcome.

We reviewed 27,571 patients retrospectively with primary arthritis as a preoperative diagnosis. Patients were divided into 4 categories based on their body mass index, or into two groups based on the body weight (<80 kg and 80 kg). Implant survivorship was estimated with use of the Cox proportional hazards model with revision for aseptic loosening as the end point. Results were stratified for sex and implant tribology. When body mass index was used the 10 years implant survival in obese versus non-obese patients was not statistically different (p=0.058), but when body weight was used a statistically different implant survivorship was found for men (p=0.009). Therefore, weight rather than than body mass index influences survival of hip prostheses, and should be used as the discriminant parameter for further studies.

Malpositioning of the acetabular component in total hip arthroplasty (THA) increases the risk of dislocation, reduces the range of motion and may contribute to bearing surface wear. During computer assisted navigation, the anterior pelvic plane is registered intraoperatively by percutaneous palpation, but this may be unreliable. The aim of our study was to evaluate the reliability of imageless navigation in acetabular positioning employing data acquisition in the supine position and surgery in the lateral position (‘flip technique’).

We report 24 patients affected by primary osteoarthritis undergoing THA in which implants were placed with a conventional free-hand technique using the acetabular transverse ligament for cup orientation. For imageless navigation we used Orthopilot-Aesculap software. All patients had a postoperative computed tomography (CT) scan at three months, using previously validated dedicated software for cup orientation. Data collected using navigation software were compared with CT measurements. The mean acetabular inclination and anteversion recorded intra-operatively using navigation software were respectively 41°5’ (SD: 9.61) and 9°5’ (SD: 4.01) respectively. The mean inclination and anteversion calculated post-operatively by the CT based image software were 44°2’ (SD 5.83) and 14°4’ (SD 6.42) respectively. There was a statistically significant difference between the anteversion values (p=0.04).

Therefore, the acquisition of parameters in the supine position with surgery performed in the lateral decubitus position creates unreliable data concerning cup anteversion using an imageless navigation system, and therefore the ‘flip technique’ cannot be recommended.

Considerable immediate periprosthetic bone density changes after implantation of femoral stems have been observed comparing DEXA measurements taken pre- and post-operatively. This is important in relation to the interpretation of DEXA studies.

We analysed these density changes under standardised experimental conditions. Five human femora were implanted with a custom made femoral stem and ten femora with a standard cementless prosthesis. Densitometry was performed at various stages of implantation.

Following rasping only slight density changes were noted (–2.7% to +0.7%). Comparing post-implantation and pre-operative measurements, all custom made stems with a proximal press-fit demonstrated clear increases in proximal periprosthetic bone density of +11% and +14%. In contrast, the standard prosthesis with a distal press-fit showed a loss of –5% and –2% in the proximal zones. Measurements following removal of the implants demonstrated hardly any density changes (0% to –4%) compared to the pre-operative measurements.

We concluded that compacting of trabecular bone or bone loss due to rasping are not the main causes of density changes. Substantial measuring errors exist. For examination of periprosthetic bone density changes, pre-operative initial measurements should not be used as a baseline for comparison. Studies should commence with an immediate postoperative measurement.

Use of a dual-mobility acetabular cup is associated with a lower risk of dislocation compared with conventional hip implants. The seleXys® DS acetabular cup combines the advantages of Charnley low-friction arthroplasty with those of dual mobility. We performed a non-randomised, prospective study of patients receiving primary hip arthroplasty, including an uncemented seleXys® DS dual-mobility acetabular cup with hydroxyapatite coating (Mathys AG, Bettlach, Switzerland) and a cemented femoral component (Stallion femoral stem Groupe Lepine, Lyon, France). The objective of the study was to evaluate longevity of the implant and the risk of dislocation. All operations were performed by a single surgeon using a posterior approach, with patients lying in the lateral decubitus position. The stem had a modular head diameter of 22.2 mm and was cemented in all patients. A total of 53 patients were studied, and the median duration of follow-up was 78.9 months. Implant survival 6 years after surgery was 98.4% (n=47; 95% CI: 89.3–99.8). There was one revision for sepsis 29 months after surgery, and one dislocation. The results of this study appear to demonstrate excellent implant survival and a low rate of dislocation using the chosen implants.

Adequate fixation at the time of cementless stem implantation depends on the operator's experience. An objective evaluation method to determine whether the stem has been appropriately implanted may be helpful. We studied the relationship between the hammering sound frequency during stem implantation and internal stress in a femoral model, and evaluated the possible usefulness of hammering sound frequency analysis for preventing intraoperative fracture.

Three types of cementless stem (BiCONTACT®, SL-PLUS®, and AI-Hip®) were used. Surgeons performed stem insertion using a procedure similar to that employed in a routine operation. Stress was estimated by finite element analysis, the hammering force was measured, and frequency analysis of hammering sound data obtained using a microphone.

Finite element analysis showed a decrease in the hammering sound frequency with an increase in the estimated maximum stress. When a decrease in frequency was observed, adequate hammering had occurred, and the continuation of hammering risked fracture. Based on the relationship between stress and frequency, the evaluation of changes in frequency may be useful for preventing the development of intraoperative fractures. Using our method, when a decrease in frequency is observed, the hammering force should be reduced. Hammering sound frequency analysis may allow the prediction of bone fractures that can be visually confirmed, and may be a useful objective evaluation method for the prevention of intraoperative periprosthetic fractures during stem insertion.

Given the recent reports of high failure rates, an improved understanding of the mechanism of failure of large diameter metal-on-metal hip arthroplasties is essential. We present clinical data and tribological analysis of a consecutive series of 74 failed large diameter metal-on-metal hips, comparing the Durom (Zimmer) with the Birmingham hip resurfacing (BHR) (Smith and Nephew). We retrospectively analysed pre-, intra-, and post-operative clinical data and measured the linear wear and component form of the explanted components using a roundness measuring machine. A significantly higher proportion of hips in the Durom group failed as a result of acetabular loosening (p=0.001) and this was supported by evidence of reduced bone in-growth on the backside of the cup. Comparison of roundness measurement revealed that the Durom hip was significantly lower wearing than the BHR (p<0.05) but the Durom femoral components were subject to significantly greater form errors (p<0.001), the pole of the head being flattened by up to 31 microns. Although the Durom hip is low wearing, reduced sphericity of the femoral component may have resulted in equatorial bearing, leading to an increased frictional torque at the cup-bone interface, preventing bone in-growth, and culminating in acetabular loosening. This supports recent clinical findings of high revision rates as a result of acetabular loosening for the Durom metal-on-metal hip system.

Early detection of pistol-grip-deformity may be beneficial in optimising the outcome and the cost effectiveness of surgery. It is important to identify reliable radiographic parameters in assessing femoro-acetabular impingement (FAI) to develop a treatment algorithm.

Radiographs of 47 patients ranging from “pistol grip deformity” to a normal head-neck-junction were measured for alpha angle and head ratio, and then classified by two different observers. The Bland-Altman plot was used for inter- and intraobserver agreement of alpha angle and head ratio. Inter- and intraobserver agreement for classification of “pistol grip deformity” was determined using weighted Cohen's kappa coefficient.

Observer I achieved a kappa coefficient of 0.97. Observer II achieved a kappa coefficient of 0.92. An interobserver kappa coefficient between 0.87 and 0.92 was achieved by using a classification system. By testing for interobserver agreement, a bias of –0.004 with an upper limit of 0.461 and a lower limit of –0.47 was seen for the ratio and a bias of –3.7 with an upper limit of 17.2 and a lower limit of –24.6 for the alpha angle.

Therefore, poor results were seen for intra- and interobserver reliability by using only a single plane for classification of “pistol grip deformity”. The strength of agreement could be improved by using a classification system (based on two planes).

The amount of fluid that may be lost into the soft tissues during hip arthroscopic surgery is unknown. We measured the volumes of irrigation fluid infused, operating time, fluid pressures and volumes of fluid recovered in 36 therapeutic hip arthroscopies. We excluded those where fluid was lost to the floor, leaving 28 patients. The majority were undergoing surgery for the treatment of femoroacetabular impingement. In 5 patients an intra-articular contrast medium was instilled, in order to establish the likely location of any extravasated fluid.

The mean operating time was 68 minutes (31 to 120), and the mean infusion pressure was 46 mm Hg (30 to 70). The mean volume of infused fluid was 9677 ml (95% confidence interval (CI) 7715 to 11638) and the mean volume of fluid recovered was 8544 ml (95% CI 6715 to 10373). The mean fluid extravasation loss into the peri-articular tissues was 1132 ml (95% CI 808 ml to 1456 ml). There was a significant correlation between the volume of extravasated fluid and both the length of operation and the volume of infused fluid used. We had no adverse events in our series.

During arthroscopic hip surgery more than a litre of irrigation fluid may be extravasated into the soft tissues. In order to reduce problems related to this we attempt to keep operating times low, and maintain intra-operative fluid pressures as low as possible.

We describe one- to three-year results of a novel use of fibrin glue in the treatment of cartilage damage by arthroscopy in the hip. This technique uses the microfracture technique and fibrin adhesive to bond delaminated articular cartilage to the underlying subchondral bone. This is generally performed in conjunction with treatment of underlying pathology such as femoroacetabular impingement.

Patients were assessed using the modified Harris Hip Score (MHHS) pre- and post-operatively, and statistical significance determined by Student's t-test. We report the mid-term results of 43 patients with femoroacetabular impingement who have undergone this technique for re-attachment of delaminated chondral flaps.

There was a statistically significant improvement in MHHS at a mean of 28 months (16 to 42 months) after surgery (p<0.0001). The MHHS for pain improved significantly from 21.8 (95% CI 19.0 to 24.7) pre-operatively to 35.8 (95% CI 32.6 to 38.9) post-operatively (p<0.0001). The MHHS for function also showed significant, although more modest, improvements from 40.0 (95% CI 37.7 to 42.3) pre-operatively to 43.6 (95% CI 41.4 to 45.8) post-operatively (p=0.0006). There were three patients who had early (within 12 months of the index procedure) revision arthroscopy for iliopsoas pathology. Arthroscopic repair of delaminated acetabular articular cartilage using fibrin adhesive is a useful technique in the treatment of early cartilage damage. We have seen encouraging mid-term results, although further studies are warranted.

Surgical treatment of femoral neck fractures is associated with a significant impact on quality of life. The aim of this study was to determine the long-term influence of displaced femoral neck fractures treated by bipolar hemiarthroplasty on the activities of daily living, quality of life and social dependency.

We studied 487 geriatric patients treated in the years 1989 to 2003. At the beginning of follow-up in 2004, 166 patients were alive and evaluation was carried out on 145 patients (87.3%) at 91.3 (14 - 244) months postoperatively by a standardized questionnaire. All enrolled patients had been treated with cemented bipolar hemiarthroplasty for a displaced femoral neck fracture. Patients were evaluated concerning their average pre- and postoperative ability to walk, the need for assisting devices, type of residency and the SF-12® Score.

Femoral neck fracture and hemiarthroplasty had a significant influence on all recorded aspects of quality of life. Even though almost two thirds of the patients needed assisting devices to walk after surgery, about two thirds returned to their original type of accommodation and the majority reached their original degree of mobility. Compared to a normal population no significant impact was observed on the quality of life measured by the SF-12® score.

We consider bipolar hemiarthroplasty an effective treatment option for displaced femoral neck fractures in geriatric patients. Most patients returned to their original type of accommodation and level of mobility, even though the majority required a number of assisting devices to do so.

Hip fractures are common injuries in the elderly, with significant mortality and morbidity from several factors. Many of these patients have cardiac disease, and some develop cardiac complications which may increase mortality.

Troponin T is a marker of myocardial injury but can be raised in other conditions. Patients over 60 years admitted with hip fracture during the study period had their troponin T measured on admission and postoperatively. Assay was performed after the patient had completed their treatment. We report the results of this study one year after the last patient was admitted.

108 patients were recruited. The average age was 84 years, 86% were female. The mean hospital stay was 20 days. This study found that 27% of hip fracture patients had some increase in the troponin T levels in the peri-operative period. This increase was not associated with an increase in early mortality, but there was an increase in one-year mortality for those with an increase in troponin T (45% versus 22%, p=0.03). These findings indicate that the routine measurement of troponin T does not correlate with acute mortality and is not necessary without evidence of an acute cardiac event.

We describe a patient who developed a mass extending into the pelvis, five years after a metal-on-polyethylene total hip arthroplasty (THA). The histological pattern of perivascular lymphocytic infiltrate and fibrinoid necrosis was more in keeping with a metal-on-metal bearing failure. The pseudotumour compressed the femoral vein causing a deep venous thrombosis.

There has been increasing focus on bone conservation through proximal fixation in primary hip arthroplasty. However, the debate regarding fixation in revision arthroplasty and which factors influence implant choice remains less clear-cut. We report a case involving fatigue fracture of a long, distally well-fixed, uncemented revision stem. This was revised to a proximally fixed implant. This case highlights a number of issues when considering the choice of implant in hip revision surgery and raises the issue of bone conservation in revision surgery. We would suggest that in both primary and revision hip arthroplasty meticulous pre-operative consideration of the choice of implant should be undertaken, especially in the younger patient with higher expectations and functional demands.