Introduction Resurfacing hip arthroplasty is becoming an increasingly popular option in the management of hip arthritis in younger individuals. Large series from units pioneering the technique have yielded encouraging results, but smaller units have reported alarming complication rates in recent years. We report a single-surgeon series performed from within the ambit of a multicentre trial. Method Data on 49 cases in 46 patients (28 males, 18 females, age 34–68, mean 50.6) were collected. Harris Hip scores were obtained preoperatively and at follow-up (6, 12, 24, 36 and 48 months, mean 16.2). Radiological assessment included evaluation of component position and possible migration. Technical difficulties with implant insertion were recorded. Results Postoperative hip scores improved dramatically in 47 cases. 3 patients have thigh pain. In one case rotational displacement of the cup occurred over 3 months. This is asymptomatic. In 2 cases there was minor femoral neck notching during surgery, without complications. One femoral component was inserted in slight varus. There was incomplete seating of the acetabulum in 4 cases, without complications. Lateral guide pin protrusion occurred into the tissues during surgery in 2 cases, and this pin is no longer used. Painless clicking, possibly due to impingement, has been noted in 4 cases. There was 1 death, due to total mesenteric infarction. There have been no femoral neck fractures and no revisions in these cases, all performed via the anterolateral approach. Discussion Resurfacing arthroplasty is more technically demanding than total hip replacement. All cases in this series were entered in a multicentre analysis, the benefits have including regular contact with other surgeons. The procedure is conservative on the femoral side at least, and conversion to hip replacement in the event of future femoral component loosening or neck fracture should be easy, although the results of articulation between a new stemmed device and an old (worn) cup are not known. The results of this single-surgeon series from a DGH, performed within the ambit of a large multi-centre analysis, have been encouraging

There has been a rapid uptake in the use of Resurfacing Hip Replacement (RHR) in the United Kingdom, and its use is likely to accelerate both in Europe and the USA. The current level of use of RHR is not accurately known. It was decided to audit the use of RHR amongst Consultant Orthopaedic Surgeons in the United Kingdom, and to identify the number of operations performed in the last twelve month period, and the specific training undertaken before offering this procedure. A questionnaire was sent to 1600 Consultant Orthopaedic Surgeons with 894 responding. 19% had performed RHR in the previous year. Excluding surgeons that do not perform Total Hip Replacement, 23.5% of surgeons had performed RHR. 29.5% of all orthopaedic surgeons had observed RHR surgery and 23% had been on an RHR course. 65% of all consultants who had attended a course were offering RHR surgery. 7.8% of those performing RHR had neither been on a course nor observed surgery. There was no relationship between years in practice and RHR surgery. There was a weak association with British Hip Society membership and with a previous fellowship in Hip Surgery. Of those performing RHR, 72% perform less than 20 cases per year. The majority of surgeons perform 6-10 RHRs per year. Although interest in RHR is increasing, it is currently performed by the minority of consultants. Given the steep learning curve, the lack of knowledge of long-term survival, and concerns regarding metal on metal bearing surfaces, RHR should be used by surgeons with a specialist interest in hip arthroplasty. We believe RHR should be used in accordance with the guidance given by the National Institute for Clinical Excellence

Resurfacing hip arthroplasty is a successful option for the treatment of the young and active patient with hip arthritis. However, it is complicated by femoral neck fracture and avascular necrosis, which result from devascularisation during surgery. Devascularisation maybe caused by thermal necrosis. Thermal necrosis of bone has been shown to occur in temperatures of 47°C and above. We investigated the temperatures generated during femoral head preparation to see if the temperatures reached were great enough to induce osteonecrosis. Method: Eight patients with osteoarthritis underwent standard resurfacing hip arthroplasty through the posterior approach. From the first over-drilling of the femoral heads until the prosthesis was cemented in place the temperatures generated at the bone surface were recorded using an infra-red thermal imaging camera. Images were captured every 4 seconds as the operation was performed with no interference to the surgeon. Results: The maximum temperatures generated occurred during sleeve reaming at 88.4°C. Seven patients had a temperature recorded greater than 47°C. Removing the femoral caput with an oscillating saw had the highest mean temperature 62.2°C, followed by sleeve reaming (mean 48.7°C). Female patients had the lowest temperature rises and patients receiving the larger femoral prosthesis the greatest temperatures at the bone surface. Conclusions: Heat generated during femoral head preparation exceeded 47°C in all but one case. Osteonecrosis secondary to thermal insult is likely to occur during femoral head preparation. Strategies need to be devised to decrease the temperatures generated during femoral head preparation

Introduction: Resurfacing hip arthroplasty is a successful option for the treatment of the young and active patient with hip arthritis. However, it is complicated by femoral neck fracture and avascular necrosis, which may result from devascularisation during surgery. Devascularisation maybe caused by thermal necrosis. Thermal necrosis of bone has been shown to occur in temperatures of 47°C and above. We investigated the temperatures generated during femoral head preparation to see if the temperatures reached were great enough to induce osteonecrosis. Method: Eight patients with osteoarthritis underwent standard resurfacing hip arthroplasty through the posterior approach. From the first over-drilling of the femoral heads until the prosthesis was cemented in place the temperatures generated at the bone surface were recorded using an infra-red thermal imaging camera. Images were captured every 4 seconds as the operation was performed with no interference to the surgeon. Results: The maximum temperatures generated occurred during sleeve reaming at 88.4°C. Seven patients had a temperature recorded greater than 47°C. Removing the femoral caput with an oscillating saw had the highest mean temperature 62.2°C, followed by sleeve reaming (mean 48.7°C). Female patients had the lowest temperature rises and patients receiving the larger femoral prosthesis the greatest temperatures at the bone surface. Conclusions: Heat generated during femoral head preparation exceeded 47°C in all but one case. Osteonecrosis secondary to thermal insult is likely to occur during femoral head preparation. Strategies need to be devised to decrease the temperatures generated during femoral head preparation

Aim: To test the accuracy of implant positioning in using computer navigation in Resurfacing hip arthroplasty. Materials and methods: Brain Lab was used to register 13 cadavers. The component position was fine tuned to a desirable valgus angle. Wire was passed using navigation. The femoral heads were sectioned after insertion of the prosthesis. The measurements from the screen-shots and the transverse sections were analysed using AutoCad®. Results: The Brain lab Registered the femoral heads to 124.91° ± 14.25° (Range 97° −148° ) CCD. The actual neck shaft angles were 126.11° ± 5.33°. The implants were placed in an angulation’s of 131.46° ± 5.27 ° (Range 116° −137° ) and a version of −0.85° ± 2.1° this gave a valgus of 5.91° ± 13.66°. The position of the wire in the isthmus of the neck was −0.52 mm ± 0.69 mm inferior to the centre and 1.7mm ± 1.9 mm posterior to the centre on the transverse sections (n=6). The components were in 8.69° ± 4.95° (n= 6) valgus to the native neck shaft angle. In only 1 hip the femoral head implanted was of the same size as suggested by navigation, in all the rest of the hips the femoral component was of a larger size. This was because it was felt that implanting a smaller size would cause notching of the superolateral neck. Conclusion: There is a learning curve involved for registering the femoral heads using computer navigation systems, however the navigation gives the surgeon a distinct advantage of being able to choose the point of entry, implant the prosthesis in as valgus position as possible in relation to the femoral head, translate the implant anteriorly and place the peg in the centre of the femoral neck in both the planes. The computer-aided navigation can optimise the component positioning and thereby provide excellent results

Aim: To test the accuracy of implant positioning in using computer navigation in Resurfacing hip arthroplasty. Materials and methods: Brain Lab was used to register 13 cadavers. The component position was fine tuned to a desirable valgus angle. Wire was passed using navigation. The femoral heads were sectioned after insertion of the prosthesis. The measurements from the screenshots and the transverse sections were analysed using AutoCad. Results: The Brain lab Registered the femoral heads to 124.91° ± 14.25° (Range 97°–148° ) CCD. The actual neck shaft angles were 126.11° ± 5.33°. The implants were placed in an angulation’s of 131.46° ± 5.27 ° (Range 116° –137° ) and a version of –0.85° ± 2.1° this gave a valgus of 5.91° ± 13.66°. The position of the wire in the isthmus of the neck was –0.52 mm ± 0.69 mm inferior to the centre and 1.7mm ± 1.9 mm posterior to the centre on the transverse sections (n=6). The components were in 8.69° ± 4.95° (n= 6) valgus to the native neck shaft angle. In only 1 hip the femoral head implanted was of the same size as suggested by navigation, in all the rest of the hips the femoral component was of a larger size. This was because it was felt that implanting a smaller size would cause notching of the supero-lateral neck. Conclusion: There is a learning curve involved for registering the femoral heads using computer navigation systems, however the navigation gives the surgeon a distinct advantage of being able to choose the point of entry, implant the prosthesis in as valgus position as possible in relation to the femoral head, translate the implant anteriorly and place the peg in the centre of the femoral neck in both the planes. The computer-aided navigation can optimise the component positioning and thereby provide excellent results

Conservative hip arthroplasty with resurfacing of the acetabulum and the femoral head is an attractive concept particularly in young and active patients. The principal advantages are less femoral bone destruction and resection, avoidance of stress shielding in the proximal femoral shaft; however this technique don’t permit a same preservation of acetabular bone stock and a mini invasive surgical approach.

From January 2003 the Authors have performed 5 metal-on-metal Birmingham hip resurfacings in patient under the age of 58 with avascular necrosis of the femoral head (without a wide necrosis) or primary osteoarthritis. In all cases was performed a posterior approach slightly more extended to permit the release of the gluteus maximus tendon; the rehabilitation program involve immediate full weight bearing one day postoperatively. Data were collected intraoperatively and postoperatively in a prospective way.

The early clinical and radiological results are very satisfactory: resurfacing hip arthroplasty appears to be a good alternative for the treatment of young patients, permitting a preservation of femoral bone stock and early functional recovery. In our opinion the key factors for a good result is a meticulous technique and a good bone quality.

Introduction

The Birmingham Hip Resurfacing (Smith & Nephew London, UK) is the most popular hip resurfacing (HR) in the UK. However, it is now subject to two Medical Device Alerts (MDA) from the Medicines and Healthcare products Regulatory Agency (MHRA).

Introduction: The advent of metal on metal resurfacing in the United Kingdom has resulted in increasing interest in the procedure. The operation is more demanding than primary joint replacement and the complications involved are frequently peculiar to the technique. We present a single-surgeon series from a district hospital performed within the ambit of a larger multicentre study.

Method: Data on 83 cases in 80 patients (51 males, 29 females, age 34y–68y, mean age 50.6y) were collected. Patients were reviewed preoperatively and postoperatively at 6 months and annually (mean 21 months, range 1–60 months). At review Harris Hip scores were recorded with a radiological assessment to assess implant orientation. Technical difficulties with implant insertion were recorded. All cases were approached via an anterolateral exposure.

Results: Postoperative scores improved dramatically in nearly all cases. There was persistent pain in two cases, one of spinal origin, the other unexplained. 2 loose femoral components were revised at 2 and 3 years respectively years leaving the intact cup. 1 cup rotated slightly over 3 months and stopped, 4 cups were incompletely seated and 1 femoral component was inserted in slight varus. All remain asymptomatic to date. There was one unrelated death (mesenteric infarction) and no femoral neck fractures.

Discussion: Resurfacing arthroplasty is technically more demanding than total hip replacement and the exchange of experiences via a multicentre user group is important. The conservative nature of the device means that revision for fractured neck of femur (commonest cause of failure) to a stemmed implant retaining the cup is relatively easy. The results of this series are encouraging.

Introduction: The Resurfacing Hip has been increasingly popular for younger patients. Femoral neck fractures are still the main complication. The problems associated with cement such as thermal necrosis, cement debris and lack of long-term biological fixation, combined with the general use of cementless fixation in young patients invite the question whether a cementless component can be used for resurfacing hip replacement. Given that the cement may reinforce the femoral head preventing collapse, an additional question regarding the effect of bone density in cemented and cementless fixation can be asked. The hypotheses of the study are that:

High bone density will increase the yield point and stiffness of the femoral head and therefore improve the implant fixation.

Materials and Methods: Thirty-six femoral head specimens were obtained from consented patients receiving routine hip arthroplasty. The heads were stored frozen at −20oC until use. pQCT was used to analyse trabecular bone density within each head. Specimens were ranked according to bone density and were assigned to high and low bone density groups. Cemented and cementless fixations were then alternatively assigned to individual heads in each group. Thus the 4 groups included in the study were: High density cemented, high density cementless, low density cemented, and low density cementless. Implantation of Birmingham resurfacing hips was carried out according to recommended surgical procedures. For cementing groups, surgical simplex P bone cement was used. Each sample was potted in a cylindrical polyethylene block for testing. A compressive load up to 5 or 10 KN using a Hounsfield Universal Testing Machine were applied on each sample at a rate of 1 mm min-1. Load versus displacement graphs were plotted for all tests. Yield point and stiffness were measured for each sample.

Results:

For yield point, there is no significant difference between cemented or cementless resurfacing (4169 ± 1420 N vs. 3789 ± 1461 N; P = 0.434). However, the high density heads provide a significantly higher yield point than low density heads (4749 ± 1145 N vs. 3208 ± 1287 N; P = 0.01).

Discussion: Bone density plays an important role in resurfacing hip arthroplasty. Higher bone density will reduce the incidence of fractures comparing with lower density. Therefore, resurfacing THR for the older patients and those with sub-optimal bone density should be used with caution. Consequently, it is suggested that a bone density scan should be routinely applied for those patients who are considered for resurfacing hip replacement. There is no difference between the cemented and cementless fixation in reducing femoral head failure, though cement will increase the stiffness of the bone. The study suggests that cementless resurfacing hip could be an alternative design with its clinical advantages of long-term osseointegration if implant is coated with bio-active materials.

Thirty nine Birmingham Resurfacing Hip Replacements were inserted between March 1999 and December 2000. The very early results are very satisfactory in a high demand group of patients.

Because of the relative ease of revision the implants have a role as a “pre” total hip replacement. The also have an important role in cases such as osteopetrosis and previous femoral osteotomy were an intra medullary stem is difficult. The series includes two cases of arthrodesis take down.

Complications have included one dislocation in a patient with cerebral palsy and one intra operative fractured neck of femur.

However, the early studies suggest that the large metal on metal bearing does produce serum chrome and cobalt levels which may be elevated in comparison with Metasul bearings at one year. The clinical significance of this is unknown.

Introduction

Failure of metal on metal (MOM) total hip arthroplasty (THA) and resurfacing arthroplasty (HRA) due to development of adverse local tissue reaction (ALTRs) is a significant problem. The prevalence of ALTRs in asymptomatic MOM arthroplasty patients is highly variable. The purpose of this prospective, longitudinal study was to: 1) determine MRI ALTR prevalence in patients with HRA; 2) determine if patients with HRA have a greater rate of MRI ALTRs compared to control patients with ceramic on poly (COP) THA; and 3) evaluate changes in patient reported outcomes between these implant designs.

Implant malposition is one of the most common causes of failure in resurfacing arthroplasty of the hip (RAH). Recent advances in computer technology have made available navigation systems for RAH and other orthopaedic procedures. The purpose of our study was:

to develop a method to assess the accuracy of an image-free RAH navigation system;

We used the Ci-CAS RAH navigation system (DePuy - BrainLab). To facilitate measurements, an artificial leg (phantom) was constructed from machined aluminium with simulated hip and knee joints. The hip and knee articulating surfaces were synthetic bone material (Sawbones – Pacific Laboratories). An additional joint located at the trochanteric region allowed deformation in varus/valgus and ante/retroversion of the head/neck segment. Using a highly accurate digital calliper unit (FaroARM Technologies, USA) to precisely measure co-ordinates with pre-machined points on the phantom, a software program was developed to convert these local co-ordinates into a determination of actual anatomy and leg alignment. This technique was verified using repeated measurement with variable co-ordinates, giving accuracy to within 0.05 of a degree.

Simulated procedures were performed with both normal and abnormal anatomy of the proximal femur. At specific points in the procedure, information was compared between the FaroARM digital measurements and the Ci-CAS system. Repeated serial measurements were undertaken. In the setting of normal alignment, accuracy to within 0.5 degrees was demonstrated. In the setting of abnormal alignment (varus/valgus and ante/retroversion) of the proximal femur, accuracy to within 2 degrees was demonstrated.

To our knowledge, this is the first study to assess accuracy of a RAH navigation system. The study demonstrates a satisfactory level of accuracy for the Ci-CAS in both normal and abnormal anatomical settings. Currently, no international standard or methodology exists against which these results can be compared. In the near future, introduction of new navigation technologies will make crucial the development of international standards for pre-clinical validation of computer-assisted navigation systems. The present study is a first attempt to address this issue.

Aim of the study: To evaluate the results of metal-on-metal resurfacing hip arthropalsty in young patients

Materials and Methods: Between February 2000 and December 2004, this operation was performed in 181 patients (205 hips) using the posterior approach. The main indications were osteoarthritis, osteonecrosis, hip dysplasia, post-traumatic arthritis, perthe’s disease and slipped capital femoral epiphysis. There were 142 males and 39 females aged 26 to 68 years (average 47.4 years). 136 patients had a minimum 3 year follow-up (range 1–5 years). Clinical and radiological evaluation was performed at 3 months, 1 year, 2 years and 5 years from time of surgery. All patients were scored using the Charnley’s modification of Merle d’Aubigne score preoperatively and at last follow-up. Radiological evaluation included grading acetabular and femoral zones for loosening, determining stem-shaft angle, hip ratio. The endpoint for outcome evaluation was revision which was two in this series. Survivourship analysis was performed by Kaplan-Meier analysis. The results in our patients were encouraging with most returning to sporting activities at an average of 12 months. 1 patient with bilateral hip resurfacing had evidence of osteolysis after surgery and had occasional hip pain until last follow-up. Complications like neck fracture, heterotrophic ossification were not seen in our series.

Conclusion: Early results of metal-on-metal resufacing arthroplasty in our series are encouraging. Continued follow-up and evaluation remains important to determine the long term results of this operation.

Introduction and Aim: The bone preserving aspect of hip resurfacing combined with minimal wear metal-metal technology is a promising solution for the younger patient who requires a hip replacement. The purpose of this study is to evaluate the early outcomes of patients treated with the Cormet 2000 resurfacing hip prosthesis.

Method: All surgical procedures were performed by a single surgeon (DGA). Thirty-two patients, with a mean age of 52.7 years, were prospectively evaluated pre-operatively and at a minimum of one-year follow-up using standardised questionnaires, physical examinations, and radiographic evaluations.

Results: All patients rated their satisfaction with the procedure as good or excellent. Mean Harris hip scores increased from 51 pre-operatively to 92 at last follow-up. Level of pain and ability to perform activities of daily living were significantly improved compared to pre-operative scores. The mean leg length, offset and neck shaft angle were essentially restored to normal. There were no radiographic abnormalities and no significant clinical complications.

Conclusion: The short-term clinical outcome of the Cormet 2000 hip resurfacing prosthesis has been excellent.

Background

Correct positioning of the femoral component in resurfacing hip arthroplasty (RHA) is an important factor in successful long-term outcomes. The purpose of computer-assisted navigation (CAS) in resurfacing is to insert the femoral neck guide wire with greater accuracy and to help size the femoral component, thus reducing the risk of notching at the head and neck junction. Several recent studies reported satisfactory precision and accuracy of CAS. However, there is little evidence that CAS is useful in the presence of anatomical deformities of the proximal femur, which is frequently observed in young patients with secondary degenerative joint disease.

Introduction

Current standard cups of metal on metal resurfacing hip arthroplasty (RHA) have no dome holes and it is very difficult for surgeons to confirm full seating of these cups. This sometimes results in gap formation between the cup and acetabular floor. Although the incidence of initial gaps using modular press-fit cups with dome screw holes has been reported to range from 20 to 35%, few studies have reported the incidence of gap formation with monoblock metal cups and its clinical consequences in RHA. The purpose of this study was to investigate retrospectively the incidence of initial gap formation and whether the initial gap influences the clinical results in RHA.

Heterotopic ossification (HO) is a common complication following total hip replacement with a number of papers reporting an incidence of greater than 40%. In an effort to reduce the degree of contamination of the abductor muscle bed with osteoprogenitor cells, we used a plastic protective shield during the preparation and reaming of the femoral head in the hope that this would result in a decreased incidence of HO.

One hundred and forty consecutive metal-on-metal resurfacing procedures (mean age 52.3 years) utilizing the Birmingham hip prosthesis were performed between March 1999 and May 2002. Pre-operative diagnosis included osteoarthritis (105), Dysplasia (19), AVN (8), Inflammatory arthropathy (8). In the first 70 cases wet swabs packed around the femoral head were used in an attempt to reduce bone contamination. For all subsequent cases, bone contamination was controlled by the use of the plastic shield. Patients were reviewed clinically and radiologically at a mean of 36.1 (range 24–62) months post operatively. Pre-operative and follow up radiographs were assessed for presence of HO according to the Brooker classification. Harris hip and UCLA activity scores were recorded pre- and post-operatively on all patients. Three patients were lost to follow up.

Eighteen patients (12.9%) were noted to have HO on follow up radiographs. Sixteen patients in the initial group when no shield was used developed HO (Brooker I [10], II [2] & III [1]). Only two patients developed HO (Brooker I) following introduction of the protective shield. This modification in surgical technique was statistically significant in decreasing incidence of HO. All patients with radiological abnormalities were asymptomatic. We propose that this protective shield should be used during resurfacing hip arthroplasty as prophylaxis against ectopic new bone formation.

In the past, the clinical outcome of earlier types of resurfacing hip arthroplasty was often characterised by a high percentage of failures and early mobilisations. An implant retrieval of a Co-Cr head and UHMWPE cup cemented resurfacing hip prosthesis was analysed. The implant was in place 11 years, without any clinical problem for nearly 10 years. The cup was highly worn. There was a complete fracture of the interface between cement and bone at the base of the femural neck. A significant hyperplastic reaction was present at the level of the synovial membrane, with fibrin deposits, hyperplasia of lining cells and a cellular infiltrate formed mostly by macrophages, with occasional giant cells and localised groups of perivascular lymphocytes. Immunohistochemical analysis showed that all lymphocytes were of the T type and that the largest part of macrophages containing debris were not activated. Inside the prosthetic head there were only traces of ossified tissue. This picture indicated that for a long time no viable bone tissue had been in contact with the cement and bone rarefaction was massive.

The study shows an important cause of the failure of earlier types of hip resurfacing arthroplasty, namely the abnormal stress distribution that caused the complete bone rarefaction.

Aim: The purpose of the study was to compare the position of the femoral guide wire for during hip resurfacing, computer navigation and an alignment device.

Materials and Methods: 26 cadaver specimens divided in 3 randomly selected groups and 25 patients were used to evaluate the position of the femoral guide wire in resurfacing hip arthroplasty. In two groups of cadavers the Computer Navigation was used to register and template the position of the implant. The position of the guide wire was compared to the one achieved using the alignment device. In the third group of cadaver specimens only the alignment device was used to implant the guide wire. Version was determined from the transversely cut sections of the cadaver specimens. Pre operative and post operative radiographs were used for analysis. In the patient group after registration and templating the guide wire was passed using the alignment device.

Results: There was no notching of the superior femoral neck in either of the groups. The mean and standard deviation of the anatomic neck-shaft angles was 124.91? ? 14.25?. The wire-shaft angle in the Navigation group was 131.46? ? 5.27? and in the alignment device group 134.08? ? 3.80?. In the navigation group the wire was in 0.85? ? 2.15? of retroversion as compared to 1.38? ? 4.19? of anteversion in Jig group. The position of the wires at the narrowest cross section of the femoral neck is shown in figure. The wire shaft angle as per navigation was 134.44(±5.55) as compared to 134.74 (±5.11).

Conclusion: The alignment device consistently positioned the wire more valgus and anteverted than Computer aided navigation. In all cases, the wire position was well within acceptable limits. Computer aided navigation does not seem to offer distinct advantages in resurfacing hip replacements.