Aims

Hip resurfacing arthroplasty (HRA) is typically indicated for young and active patients. Due to the longevity of arthroplasty, these patients are likely to undergo revision surgery during their lifetime. There is a paucity of information on the long-term outcome of revision surgeries performed after failed HRA. The aim of our study was to provide survivorship data as well as clinical scores after HRA revisions.

Introduction: Management of osteonecrosis of the hip for Ficat stage III and IV disease remains controversial with the average age of the patients in the mid ‘30’s, and inferior long-term results of THA for this group. Consequently, some surgeons have favored bone-preserving procedures, and hemiresurfacing arthroplasty has been our preferred method of treatment.

Materials and Methods: Fifty-five hips (47 patients) with Ficat Stage II, III, or early IV osteonecrosis treated with hemiresurfacing by a single surgeon (HCA) were reviewed. The average age of the patients was 34 years (range, 18–52) and 74% of the patients were men. Three different resurfacing materials were used over the years: Titanium (11 hips), Alumina (12 hips), and cobalt-chromium (32 hips).

Results: The average follow-up was 13 years (range 2.6–26.5). There were no dislocations, femoral neck fractures, or osteolysis. The average UCLA hip scores for pain, walking, function, and activity improved from 4.8, 5.8, 5.2, and 4.2 to 7.9, 8.7, 7.7, and 5.6, respectively, at last follow-up. The Kaplan-Meier survival estimate was 81.8%, 58.3%, and 44.2% at 5, 10, and 15 years, using any revision as end point. Seventeen hips were converted: 15 for acetabular cartilage wear, one for enigmatic pain at 12 months, and one for sepsis at 3 months. We found no difference in survivorship between component materials (log-rank test; p=0.447).

Discussion: This experience indicates a greater that 80% survivorship at 5 years for this conservative procedure. Four patients have passed the 20-year landmark (one of them was revised at 23 years). The pain and function scores are lower than with THA or modern full resurfacing devices. A shorter duration of symptoms before surgery is favorable to survivorship of the procedure because we believe that articular cartilage is healthier. When necessary, conversion to total hip replacement is similar to a primary THA.

Introduction: The results of total hip arthroplasty and prior hip resurfacing designs with polyethylene in osteonecrosis (ON) have been less satisfactory than for patients with other etiologies. Metal-on-metal resurfacing is bone preserving and permits a wide selection of revision options for young patients.

Methods: From a cohort of 1000 hips of all etiologies, 84 hips (70 patients, average age 40 years), with ON Ficat Stage III (19 hips) and IV (65 hips) were treated with hybrid metal-on-metal resurfacing. There were 81% men and 19% women. One-third of the patients had previous surgeries including core decompression (17 hips), hemi-resurfacing arthroplasty (3 hips), pinning (5 hips), free vascularized fibula graft (2 hips) and Judet graft (1 hip). Seventy-one hips (85%) presented with femoral head defects larger than 1 centimeter.

Results: The average follow-up was 6 years (1-1). The average femoral component size was 46 millimeters. The clinical scores were comparable to that of the rest of the cohort except for the activity score which was lower in average (7.0 vs. 7.5, p=0.0015). Three hips were revised: 2 for femoral loosening at 22 and 61 months, and one for a fracture of the acetabular wall (over reaming in osteopenic bone) with protrusio of the cup one day post surgery. There were no other complications. Radiographic analysis revealed 3 cases of neck narrowing (1 bilateral) and 2 cases of femoral radiolucencies in 3 zones around the metaphyseal stem. The Kaplan-Meier 5-year survival estimate was 97.1% (95% Confidence Interval 88.7 to 99.2). There have been no femoral component loosenings for patients implanted after August of 1997.

Discussion: Our results highlight that the etiology of osteonecrosis itself does not constitute a contraindication for resurfacing despite large defects. Technique is critical in achieving initial femoral fixation and promoting long-term durability.

Introduction: The purpose of the present study was to assess the clinical results of metal-on-metal hip resurfacing for the treatment of hip arthrosis in patients with a BMI of 30 or more.

Materials and Methods: From a consecutive series of over 1000 Conserve® Plus metal-on metal hybrid resurfacings, 148 hips were resurfaced in 138 patients with a BMI of 30 or more at the time of surgery. Average age was 49.4 years (range, 18 to 72) with 88% male. The average weight was 104.6 kg (range 74 to 164) and average BMI 33.4 (30.0 to 46.4). “Idiopathic” OA was the dominant etiology with 80.0%. The femoral metaphyseal stem was cemented in 43 hips and press-fit in the remaining 105. All acetabular components were press-fit.

Results: Average follow-up was 6.2 years (range, 2.0 to 10.2). UCLA hip scores improved significantly (pain: 3.5 to 9.4; walking: 5.9 to 9.5; function: 5.4 to 9.2; activity: 4.3 to 7.1). There were no cases of acetabular or femoral component loosening. 2 hips (1.4%) were revised, 1 for femoral neck fracture and one for acetabular cup protrusio the day after surgery in a bilateral patient with poor bone quality. 3 hips (2.0%) have radiolucencies about the femoral stem. All are asymptomatic and none have progressed for an average of 5.2 years (range 4.5 to 6.8). There were no revisions for any reason and no radiolucencies observed in patients with a BMI of 35 or more (n=27).

Conclusions: Metal-on-metal resurfacing arthroplasty of the hip is performing extremely well in patients with high BMI, in contrast with the results of conventional THR. These results are in agreement with our previous finding that weight is protective of prosthesis durability with resurfacing. This could be explained by a greater fixation area on the femoral side, a greater bone mineral density, and a slightly reduced (but still high) activity level in this patient population compared to patients with a BMI less than 30 (7.1 vs 7.6, p=0.002).

Introduction: ‘Revisability’ has been touted as one of the major advantages of resurfacing arthroplasty of the hip. However, this theoretical advantage has never been clearly demonstrated. The objective of the present study was to test the hypothesis that a failed, modern generation metal-on-metal resurfacing arthroplasty (MMRA) can be converted to a total hip (THA) as easily and with comparable results as a primary (THA).

Methods: Twenty-two failed MMRA’s in 21 patients with an average age of 49.5 years (23 – 72 years) were converted to a THA. In 18 hips, the acetabular component was retained, and in 4 hips both components were revised. The control group of primary THA’s, implanted during the same time period by the same surgeon, consisted of 64 patients with an average age of 50.8 years (27 – 64 years).

Results: There was no significant difference in operative time, blood loss and complication rates between the conversions and the controls. The average follow-up was 47 months (12 – 113 months) for the conversions and 57 months (24 – 105 months) for the controls. Clinical outcomes measures were comparable with average Harris Hip Scores of 92.7 and 90.3 for the MMRA conversions and primary THA’s, respectively. The UCLA activity scores were 6.6 and 6.4 in the conversion group and THA group, respectively. There have been no cases of aseptic loosening of the femoral or acetabular components in either group, and there have been no dislocations after MMRA conversion.

Conclusion: Conversion of failed MMRA to a THA appears to be as safe and effective as a primary THA.

The femoroacetabular conflict is a recognized cause of hip pain in young patients. It is associated with rim tears. Two types of conflict have been described: impingement due to retroversion of the acetabulum and «cam effect» associated with insufficient head/neck offset. A recent subject of debate has been isolated treatment of the rim tear without treating the often unrecognized bone anomaly. The purpose of this study was to assess short-term outcome after surgical remodeling of the head/neck junction for the treatment of femoroacetabular conflicts.

Material and methods: There were 37 hips (18 men and 16 women) with chronic pain for more than three months. Mean patient age was 41 years (range 24–52). Preoperative 3D CT and MRI with gadolinium arthrography were available for all patients. Surgical remodeling of the head/neck junction via digastric trochanterotomy with surgical dislocation was performed. Preoperatively, the mean Notzli alpha angle was 65.6° (range 42–95°). Among the 34 patients, only four practiced sports requiring large range hip motion. MRI revealed a rim lesion in all patients. The following tests were performed: UCLA hip test, WOMAC (Western Ontario McMaster Osteoarthritis) index, and SF-12.

Results: Mean follow-up was 2.5 years (range 2–4); pre- and postoperative scores were: WOMAC 59.2 and 81.0 (p< 0.001), UCLA scores 4.2 and 7.9 for pain, 7.3 and 9.0 for gait, 6.2 and 8.5 for function, 4.3 and 6.9 for activity (p< 0.05). The physical component of the SF-12 improved from 37.4 to 44.2 (p< 0.006) and the mental component from 46.0 to 51.6 (p< 0.03). None of the hips required revision to modify the joint configuration. Two complications were noted: one rupture of the greater trochanter and one heterotopic ossification requiring resection. Osteonecrosis was not observed. The trochanter implants were removed in nine patients because of pain.

Discussion: The femoroacetabular conflict results from insufficient concavity of the anterolateral head/neck junction associated with a rim tear. Correction of the bony anomaly provided significant short-term functional improvement both for the hip and for the patient’s general health. Correction of the offset by surgical dislocation of the hip is effective and safe treatment of the femoroacetabular conflict with preservation of the rim.

Legg-Calve-Perthes and slipped capital femoral epiphysis may result in alterations of the proximal femoral morphology, leading to the development of secondary hip osteoarthritis as a young adult. Hip surface arthroplasty presents special technical challenges in these patients because of the abnormal anatomy of the head and neck. We reviewed the radiographic and clinical results of patients with a history of either LCP or SCFE, who underwent hip resurfacing between 1996 and 2002. Twenty-three patients (25 hips, 14 with LCP and 11 with SCFE) underwent metal-on-metal surface arthroplasty. The average age at the time of surgery was 38.1 years and 87% of the patients were male. The mean time to follow-up was 26.9 months. UCLA pain, walking, function, and activity scores improved significantly in both groups as well as the SF-12 physical component scores. One patient with LCP required bilateral conversion to THA at 55 months postoperatively secondary to femoral component loosening. There were no dislocations or femoral neck fractures in this series. Of 11 patients who presented leg length discrepancies preoperatively, limb length was postoperatively equalized in six patients, 3 were maintained with the same amount of discrepancy, and 2 decreased their discrepancy by at least 1 cm. In Charnley Class A patients, there was no difference in femoral offset between the operated and the disease-free, contralateral hip after reconstruction.

Despite the challenges in performing hip resurfacing in this patient population, the results to date have been encouraging. Even with the limitations of resurfacing in restoring leg length and offset, the clinical results of this group of patients are comparable to those of the other etiologies.

The purpose of this study was to present our experience with femoral neck fractures that occurred after metal-on-metal hybrid surface arthroplasty and to assess their causation.

Materials and Methods: A series of 600 metal-on-metal surface arthroplasties was performed from late 1996 to early 2003 by the primary author. Failures during this period were assessed radiographically and with implant retrieval analysis to determine the cause of failure. There were five femoral neck fractures in this series (0.83%).

In addition, a review of the femoral neck fracture cases identified from the Conserve+ Multi-Center IDE was performed (19 femoral neck fractures in 1203 cases, 1.6%).

Results: Lead Author Series: Four of the five fractures occurred at the component–neck junction in the first five months after surgery (average three months). All were associated with a traumatic episode but they also had structural and or technical risk factors, which weakened the constructs. The most important technical deficiency was failure to cover all of the reamed bone with the component in three of the five. One fracture was associated with histological changes consistent with osteonecrosis of the head in a case of overpenetration of cement in very soft bone.

Multi-Center IDE: Additional risk factors were identified among which impingement of the neck with the acetabular component, notching of the lateral femoral neck cortex, and leaving the femoral component proud (not completely seated).

Conclusion: It is important to avoid or at least minimize notching the femoral neck by performing the cylindrical reaming at the recommended angle of 140° and to stop reaming before the reamer touches the lateral cortex. Osteophytes should be judiciously removed only if there is a notable impingement when the hip is at 90° of flexion and internally rotated. We believe that understanding the factors that contribute to femoral neck fracture after surface arthroplasty may reduce the already low incidence of this mode of failure.

Introduction and Aims: To review the medium-term clinical and x-ray results of metal-on-metal Surface Arthroplasty (MMSA) in DDH, using the Conserve Plus™.

Method: Fifty hips (44 patients, avg. age 42.7 years) with DDH were treated with hybrid MMSA. Seventy-five percent were female. Ten percent had prior osteotomies. Twenty-five percent had acetabular cysts that were grafted and 64% had femoral cysts (> 1cm in size) and one was grafted. All cases were Crowe Class 1 or 2. A posterior approach was used in all but one case.

Results: Mean follow-up was 4.9 years (3.8–7.8). UCLA hip scores were 3.2, 5.9, 5.5 and 4.4 pre-op and 9.2, 9.5, 9.4 and 7.1 at last follow-up for pain, walking, function and activity. SF-12 scores normalised. Range of motion was 126.6 degrees, 80.5 degrees and 83.2 degrees at last follow-up for flexion, abduction-adduction, and rotation arcs. Four hips were converted to THA: 2 for femoral neck fracture at two and five months, one for recurrent subluxations due to poor offset and impingement due to prior multiple osteotomies, and one for femoral component aseptic loosening. Four technical complications successfully resolved: one trochanteric non-union, one post-op dislocation (closed reduction), one component mismatch (acetabular component exchange) and one femoral nerve palsy. X-ray analysis: two patients presented complete radiolucencies around the metaphyseal stem.

Conclusion: SA is stable, except for one subluxation due to impingement with poor offset compared to seven to 10% with THA. The socket fixation is secure without adjunct fixation with grafts incorporating whereas prior SA with PE were poor due primarily to socket loosening. Femoral bone preparation is critical to avoid fractures and loosening.

Introduction and Aims: The purpose of the present study was to review the early results and clinical performance of FDA approved large unipolar heads (36mm and greater) used with a metal-on-metal (MM) bearing.

Method: Fourteen stem type prostheses were implanted in 14 patients. There were eight primary THA, and six conversions of surface arthroplasties in which thin-walled (5mm) porous coated MM sockets were maintained. Mean age was 55.4 years (range 30–72 years). There were nine males and five females. Dislocation precautions were discontinued after capsular healing (six weeks). The initial etiology was OA in 78%.

Results: The median head size was 44mm (36–52) and socket size 54mm. Mean follow-up time was 29.1 months (range 12–81). UCLA hip scores improved for pain, walking, function, and activity from 4.8, 6.2, 6.1, and 4.8 pre-operatively to 9.3, 8.5, 7.5, and 5.4 postoperatively. Range of motion normalised. There were no complications.

Conclusion: This investigation shows excellent clinical results, and suggests that dislocation can be avoided by an anatomical THR with the use of large unipolar femoral heads and thin sockets with low wear bearings. The advantage of MM is the ability to manufacture thin shells with porous beads for fixation and preserve ace-tabular bone stock.

Introduction: THR is still the standard of care for young arthritic patients. However, failure rates remain high at 10 years follow-up, with rates of up to 33% in all cemented designs and 10.5% in cementless designs. With the arrival of new, more wear-resistant bearings, Surface Arthroplasty (SA) has become a viable and promising solution for this patient population. The purpose of the present study was to investigate the results of a metal-on-metal (M/M) hybrid SA and identify appropriate criteria for patient selection.

Method: The first 400 hips (of 620) in 355 patients underwent M/M hybrid surface arthroplasty. Mean age 48.2; 73% males, 27% females; 198 Charnley Class A; 139 Class B and 18 Class C. Diagnosis at surgery: OA 64%, DDH 11%, ON 9%, Post-traumatic 8%, Inflammatory arthritis 3%, SCFE and LCP 4%, Melorheostosis 0.3%.

Results: Mean follow-up 5.2 years (3.9–7.8). Average UCLA hip scores post-op: pain 9.4, walking 9.5, function 9.4, and activity 7.7. The SF-12 physical and mental components were respectively, 31.2 and 46.8 pre-op and 50.1 and 53.0 post-op. Fifteen hips were converted to THA (nine in the first 102): two neck fractures, 10 femoral loosenings, one socket protrusio due to over-reaming, one subluxation due to impingement and one sepsis. The three most important risk factors for femoral loosening and radiolucencies were large cyst formation (p=0.0067), female gender (p=0.0001), and lighter weight in male patients (p=0.0003). The occurrence of femoral loosening or lucency was 18% for the first 100 cases, 9% for the second, 8% for the third, and 1% for the last 100 cases.

Conclusion: Clinical results are excellent, despite very high activity levels. The experience with SA of all cemented metal/UHMWPE bearing demonstrated failure rates of 15 to 33% at three years. At longer follow-up, the preliminary experience is encouraging (3.75% failure rate). Dislocation is rare, and acetabular fixation secure. Initial femoral fixation is critical, as the fixation area is small, especially with osteopenia and cystic degeneration. Cementing the femoral metaphyseal stem appears as a meaningful technical improvement towards the prevention of early femoral radiolucencies. None of the 59 cemented metaphyseal stem had any radiolucency at last review.

Introduction and Aims: The purpose of this study was to validate in a clinical series a method to measure femoral component migration in surface arthroplasty based on the principles of EBRA-FCA.

Method: The first 400 hybrid MMSA in 355 patients have an average of 3.5 years follow-up (range two to six years). The average age was 48 years, 73% were men and 35% had secondary osteoarthritis. All patients were evaluated prospectively at three months and then yearly. We reviewed the x-rays of 26 hips that had undergone metal-on-metal resurfacing using EBRA-FCA. Minimum follow-up was 3.5 years. Group 1was free of any clinical or radiographic signs of loosening (17 hips); group 2 had failed from femoral component aseptic loosening (nine hips). Mean age for the whole group was 50.7 years (28–67). Sixty-six percent were male and 63% were operated for osteoarthritis. We recorded migrations of 2mm or greater and the time to initiation of migration.

Results: Group 2 showed significantly greater migration than group 1, respectively: 4.57 mm versus 1.62mm for centre of the head (p=0.005), 4.51mm versus 1.05mm for stem tip (p=0.001). Initial migration was significantly sooner in group 2 versus group 1: 19 months versus 29.2 months (p=0.030). In group 2, the average time to first migration detected with EBRA-FCA was significantly less than time to first clinical symptoms: 19 months versus 29.5 months (p=0.003). More importantly, the time to detection of significant migration was shorter than the time to detection of the first metaphyseal stem radiolucency: 19 months versus 24.3 months (p=0.028).

Conclusion: EBRA-FCA represents a reliable tool to measure migration of femoral component, which may become essential in the assessment of the clinical performance of MMSA. It is best used in large clinical series with standardised x-ray technique and limiting the number of observers.

Studies on the migration of an implant may be the only way of monitoring the early performance of metal-on-metal prostheses. The Ein Bild Roentgen Analyse - femoral component analysis (EBRA-FCA) method was adapted to measure migration of the femoral component in a metal-on-metal surface arthroplasty of the hip using standard antero-posterior radiographs. In order to determine the accuracy and precision of this method a prosthesis was implanted into cadaver bones. Eleven series of radiographs were used to perform a zero-migration study. After adjustment of the femoral component to simulate migration of 3 mm the radiographs were repeated. All were measured independently by three different observers.

The accuracy of the method was found to be ± 1.6 mm for the x-direction and ± 2 mm for the y-direction (95% percentile). The method was validated using 28 hips with a minimum follow-up of 3.5 years after arthroplasty. Seventeen were sound, but 11 had failed because of loosening of the femoral component. The normal (control) group had a different pattern of migration compared with that of the loose group. At 29.2 months, the control group showed a mean migration of 1.62 mm and 1.05 mm compared with 4.39 mm and 4.05 mm in the failed group, for the centre of the head and the tip of the stem, respectively (p = 0.001). In the failed group, the mean time to migration greater than 2 mm was earlier than the onset of clinical symptoms or radiological evidence of failure, 19.1 versus 32.2 months (p = 0.001) and 24.8 months (p = 0.012), respectively.

EBRA-FCA is a reliable and valid tool for measuring migration of the femoral component after surface arthroplasty and can be used to predict early failure of the implant. It may be of value in determining the long-term performance of surface arthroplasty.

Aims: determine risk factors associated with component loosening so that measures can be implemented to improve component durability. Methods: The þrst 300 patients with Wright Medical Conserve Plusª metal-on-metal hip resurfacings were analyzed radiographically for radiolucencies and failed components were analyzed histologically after the components were sectioned. The group average age was 48 years, 75% were male, and most were operated for OA. At an average of 3 years, 7 hips required revision for femoral loosening, none for acetabular loosening. These included 4 of the þrst 100 cases, 1 in the 2nd 100, 2 in the 3rd 100. Radiographic lucencies were found in 9 of the 1st 100, and 3 in each of the of the 2nd and third 100. Results: The etiology of femoral loosening was found to be multifac-torial and risk factors included: substandard bone preparation, presence of large cysts or bone defects, cement technique, and patient activity.

The short metaphyseal stem serves as a useful Ç barometer È for þxation and impending loosening. Conclusions: Femoral loosening can be minimized by better patient selection and by excellent bone preparation and cement technique. Patients with compromised bone stock may still be successfully resurfaced if the extent of the defects is not excessive and/or the stem is cemented in.

Aims: Examine the short term failures of the Wright Medical Conserve Plusª metal-on-metal hip resurfacing to determine risk factors, so that measures could be implemented to prevent future failures. Methods: Two hundred and ninety six Conserve Plus hip resurfacings were performed in an FDA IDE multi-center trial. 9 femoral neck fractures occurred in 3 of the 9 centers. The time to failure ranged from less than 1 week to 21 weeks. The revised resurfaced heads were sectioned and examined by micro-radiography and histology, along with pre and post-operative radiographs and clinical histories that were discussed with the surgeons. Results: Several risk factors were identiþed including poor bone quality large or multiple cysts in the femoral head or neck, leaving reamed bone uncovered, improper implant placement and incorrect patient selection. Lessons learned from this analysis resulted in no further neck fractures to date in 369 additional Conserve Plus components that have now been implanted. Conclusions: Osteoarthritic femoral necks rarely fracture and neck fracture in resurfaced femoral heads can be largely prevented by better patient selection, improved surgical technique to prevent neck notching and better implant placement.

To review short to medium term results of a metalon-metal (M/M) hybrid surface arthroplasty (SA) for a young and active patient population.

The first 300 hips (of 564) in 263 patients underwent M/M hybrid surface arthroplasty (cementless acetabular and cemented femoral components). Demographics: mean age 48.4; 75% males, 25% females; 141 Charnley Class A; 109 Class B and 13 Class C. Diagnosis at surgery: OA 67%, DDH 10.3%, ON 8.3%, Post-traumatic 6.7%, Inflammatory arthritis and Rheumatoid Disease 4%, SCFE and LCP 3.4%, Melorheostosis 0.3%.

Mean follow-up 3.6 years (2.5–5.9). Average UCLA hip scores post-op: pain 9.4, walking 9.5, function 9.4 and activity 7.7. Average Harris Hip Score was 92.8. The SF-12 physical and mental components were respectively, 31.4 and 47.2 pre-op and 49.9 and 52.9 post-op. DEXA data suggests preservation or restoration of neck BMD.

The experience with SA of all cemented metal/ UHMWPE bearing demonstrated failure rates of 15%–33% at 3 years. At longer follow-up, the preliminary experience is encouraging (3.6% failure rate) and eventual conversions to THR are facilitated with unipolar heads. The technique preserves femoral and ace-tabular bone, dislocation is rare, and acetabular fixation secure. Initial femoral fixation is critical as the fixation area is small, especially with osteopenia and cystic degeneration. The percent of potentially adverse radiographic changes was much greater in the first 100 cases, during the time of development of instrumentation, technique, and bearing optimisation.