Between November 1997 and December 2000 we performed 27 total hip replacements in 22 patients with high congenital dislocation of the hip using porous tantalum monoblock acetabular components implanted in the true acetabular bed. Clinical and radiological evaluation was performed at regular intervals for a mean of 10.2 years (8.5 to 12). The mean Harris Hip Score improved from 48.3 (15 to 65) pre-operatively to 89.5 (56 to 100) at the final follow-up. The mean Oxford Hip Score was 49.5 (35 to 59) pre-operatively and decreased to 21.2 (12 to 48) at one year and 15.2 (10 to 28) at final follow-up. Migration of the acetabular component was assessed with the EBRA software system. There was a mean migration of 0.68 mm (0.49 to 0.8) in the first year and a mean 0.89 mm (0.6 to 0.98) in the second year, after excluding one initial excessive migration. No revision was necessary for any reason, no acetabular component became loose, and no radiolucent lines were observed at the final follow-up. The porous tantalum monoblock acetabular component is an implant offering adequate initial stability in conjunction with a modulus of elasticity and porosity close to that of cancellous bone. It favours bone ingrowth, leading to good mid-term results.
We evaluated the short-term of 0 to 90 days and the longer term, up to 12.7 years, mortality for patients undergoing primary total hip replacement (THR) in Denmark in comparison to the general population. Through the Danish Hip Arthroplasty Registry we identified all primary THRs undertaken for osteoarthritis between 1 January 1995 and 31 December 2006. Each patient (n = 44 558) was matched at the time of surgery with three people from the general population (n = 133 674). We estimated mortality rates and mortality rate ratios with 95% confidence intervals for THR patients compared with the general population. There was a one-month period of increased mortality immediately after surgery among THR patients, but overall short-term mortality (0 to 90 days) was significantly lower (mortality rate ratio 0.8; 95% confidence interval 0.7 to 0.9). However, THR surgery was associated with increased short-term mortality in subjects under 60 years old, and among THR patients without comorbidity. Long-term mortality was lower among THR patients than in controls (mortality rate ratio 0.7; 95% confidence interval 0.7 to 0.7). Overall, THR was associated with lower short- and long-term mortality among patients with osteoarthritis. Younger patients and patients without comorbidity before surgery may also experience increased mortality after THR surgery, although the absolute risk of death is small.
Delayed rather than early reconstruction of the anterior cruciate ligament is the current recommended treatment for injury to this ligament since it is thought to give a better functional outcome. We randomised 105 consecutive patients with injury associated with chondral lesions no more severe than grades 1 and 2 and/or meniscal tears which only required trimming, to early (<
two weeks) or delayed (>
four to six weeks) reconstruction of the anterior cruciate ligament using a quadrupled hamstring graft. All operations were performed by a single surgeon and a standard rehabilitation regime was followed in both groups. The outcomes were assessed using the Lysholm score, the Tegner score and measurement of the range of movement. Stability was assessed by clinical tests and measurements taken with the KT-1000 arthrometer, with all testing performed by a blinded uninvolved experienced observer. A total of six patients were lost to follow-up, with 48 patients assigned to the delayed group and 51 to the early group. None was a competitive athlete. The mean interval between injury and the surgery was seven days (2 to 14) in the early group and 32 days (29 to 42) in the delayed group. The mean follow-up was 32 months (26 to 36). The results did not show a statistically significant difference for the Lysholm score (p = 0.86), Tegner activity score (p = 0.913) or the range of movement (p = 1). Similarly, no distinction could be made for stability testing by clinical examination (p = 0.56) and measurements with the KT-1000 arthrometer (p = 0.93). Reconstruction of the anterior cruciate ligament gave a similar clinical and functional outcome whether performed early (<
two weeks) or late at four to six weeks after injury.
Pseudotumours are a rare complication of hip resurfacing. They are thought to be a response to metal debris which may be caused by edge loading due to poor orientation of the acetabular component. Our aim was to determine the optimal acetabular orientation to minimise the risk of pseudotumour formation. We matched 31 hip resurfacings revised for pseudotumour formation with 58 controls who had a satisfactory outcome from this procedure. The radiographic inclination and anteversion angles of the acetabular component were measured on anteroposterior radiographs of the pelvis using Einzel-Bild-Roentgen-Analyse software. The mean inclination angle (47°, 10° to 81°) and anteversion angle (14°, 4° to 34°) of the pseudotumour cases were the same (p = 0.8, p = 0.2) as the controls, 46° (29° to 60°) and 16° (4° to 30°) respectively, but the variation was greater. Assuming an accuracy of implantation of ± 10° about a target position, the optimal radiographic position was found to be approximately 45° of inclination and 20° of anteversion. The incidence of pseudotumours inside the zone was four times lower (p = 0.007) than outside the zone. In order to minimise the risk of pseudotumour formation we recommend that surgeons implant the acetabular component at an inclination of 45° (± 10) and anteversion of 20° (± 10) on post-operative radiographs. Because of differences between the radiographic and the operative angles, this may be best achieved by aiming for an inclination of 40° and an anteversion of 25°.
The survivorship of contemporary resurfacing arthroplasty of the hip using metal-on-metal bearings is better than that of first generation designs, but short-term failures still occur. The most common reasons for failure are fracture of the femoral neck, loosening of the component, osteonecrosis of the femoral head, reaction to metal debris and malpositioning of the component. In 2008 the Australian National Joint Registry reported an inverse relationship between the size of the head component and the risk of revision in resurfacing hip arthroplasty. Hips with a femoral component size of ≤ 44 mm have a fivefold increased risk of revision than those with femoral components of ≥ 55 mm irrespective of gender. We have reviewed the literature to explore this observation and to identify possible reasons including the design of the implant, loading of the femoral neck, the orientation of the component, the production of wear debris and the effects of metal ions, penetration of cement and vascularity of the femoral head. Our conclusion is that although multifactorial, the most important contributors to failure in resurfacing arthroplasty of the hip are likely to be the design and geometry of the component and the orientation of the acetabular component.
Digital templating in hip replacement is commonly performed with radiological markers to determine the magnification. The latter can also be determined by measuring the distance from the x-ray focal spot to the object and the distance from the x-ray focal spot to the radiological cassette or image receptor. We used post-operative radiographs of total hip replacements and hemiarthroplasties from 22 patients to calculate the magnification using both methods. The accuracy of each method was ascertained by measuring the size of the head of the implant projected on to the radiographs and comparing the result with the known size recorded in the medical records. The accuracy was found to be similar with a mean absolute measurement error of 2.6% ( We conclude that the distance measuring method is as accurate as the radiological marker method, but may avoid some of the disadvantages such as misplacement of the marker or placement outside the radiological field. It may also be more acceptable to the patient and radiographer.
A 30-year-old man presented with pain and limitation of movement of the right hip. The symptoms had failed to respond to conservative treatment. Radiographs and CT scans revealed evidence of impingement between the femoral head-neck junction and an abnormally large anterior inferior iliac spine. Resection of the hypertrophic anterior inferior iliac spine was performed which produced full painless restoration of function of the hip. Hypertrophy of the anterior inferior iliac spine as a cause of femoro-acetabular impingement has not previously been described.
A total of 218 patients with unilateral anterior cruciate ligament deficiency were randomly assigned to one of four groups. In group A an anatomical double bundle anterior cruciate ligament reconstruction was performed; group B were treated by a single bundle using an Endobutton for femoral fixation; in group C by a single bundle using RigidFix cross pins for femoral fixation; and in group D by a single bundle using a bioabsorbable TransFix II screw for femoral fixation. For tibial fixation a bioabsorbable Intrafix interference screw was used for all the groups and the graft was fashioned from the semitendinosus and gracilis tendons in all patients. In all, 18 patients were lost to follow-up. The remaining 200 were subjected to a clinical evaluation, with assessment of the anterior drawer, Lachman’s and the pivot-shift tests, and KT-1000 arthrometer measurement. They also completed the International Knee Documentation Committee, Lysholm knee and Tegner activity scores. At a mean of 29 months (25 to 38) follow-up there were no significant differences concerning time between injury and range of movement and Lysholm knee scores among the four groups. However, the double bundle method showed significantly better results for the pivot-shift test (p = 0.002). The KT 1000 measurements showed a mean difference between the reconstructed knee and the patients’ normal knee of 1.4 mm in the double bundle group and 2.4 mm in the single bundle group; which was statistically significant. The Lachman and anterior drawer tests also showed superior results for the double bundle method. The International Knee Documentation Committee scale showed no significant difference among the groups (p <
0.001). On clinical evaluation the double bundle group showed less laxity than the single bundle groups. However, regardless of the technique, all knees were improved by anterior cruciate ligament reconstruction compared with their pre-operative status.
Digital radiography is becoming widespread. Accurate pre-operative templating of digital images of the hip traditionally involves positioning a calibration object at its centre. This can be difficult and cause embarrassment. We have devised a method whereby a planar disc placed on the radiographic cassette accounts for the expected magnification. Initial examination of 50 pelvic CT scans showed a mean hip centre distance of 117 mm (79 to 142) above the gluteal skin. Further calculations predicted that a disc of 37.17 mm diameter, placed on the cassette, would appear identical to a 30 mm sphere placed at the level of the centre of the hip as requested by our templating software. We assessed accuracy and reproducibility by ‘reverse calibration’ of 20 radiographs taken three months after hip replacement using simultaneous sphere and disc methods, and a further 20 with a precision disc of accurate size. Even when variations in patient size were ignored, the disc proved more accurate and reliable than the sphere. The technique is reliable, robust, cost effective and acceptable to patients and radiographers. It can easily be used in any radiography department after a few simple calculations and manufacture of appropriately-sized discs.
The patellar clunk syndrome describes painful catching, grinding or jumping of the patella when the knee moves from a flexed to an extended position after total knee replacement (TKR). The posterior stabilised TKR had been noted to have a higher incidence of this problem. Mobile-bearing posteriorly stabilised TKRs have been introduced to improve patellar tracking and related problems by a mechanism of self-alignment. We evaluated the patellar clunk syndrome in 113 knees in 93 patients with such a TKR at a mean follow-up of 2.3 years (2.0 to 3.2). The syndrome was identified in 15 knees (13.3%). Logistic regression analysis showed that the absolute value of the post-operative angle of patellar tilt was significantly associated with the occurrence of patellar clunk (p = 0.025). Patellar tracking should be carefully checked during surgery.
Hydroxyapatite-coated standard anatomical and customised femoral stems are designed to transmit load to the metaphyseal part of the proximal femur in order to avoid stress shielding and to reduce resorption of bone. In a randomised in vitro study, we compared the changes in the pattern of cortical strain after the insertion of hydroxyapatite-coated standard anatomical and customised stems in 12 pairs of human cadaver femora. A hip simulator reproduced the physiological loads on the proximal femur in single-leg stance and stair-climbing. The cortical strains were measured before and after the insertion of the stems. Significantly higher strain shielding was seen in Gruen zones 7, 6, 5, 3 and 2 after the insertion of the anatomical stem compared with the customised stem. For the anatomical stem, the hoop strains on the femur also indicated that the load was transferred to the cortical bone at the lower metaphyseal or upper diaphyseal part of the proximal femur. The customised stem induced a strain pattern more similar to that of the intact femur than the standard, anatomical stem.
Femoroacetabular impingement is a cause of hip pain in adults and is potentially a precursor of osteoarthritis. Our aim in this study was to determine the prevalence of bilateral deformity in patients with symptomatic cam-type femoroacetabular impingement as well as the presence of associated acetabular abnormalities and hip pain. We included all patients aged 55 years or less seen by the senior author for hip pain, with at least one anteroposterior and lateral pelvic radiograph available. All patients with dysplasia and/or arthritis were excluded. A total of 113 patients with a symptomatic cam-impingement deformity of at least one hip was evaluated. There were 82 men and 31 women with a mean age of 37.9 years (16 to 55). Bilateral cam-type deformity was present in 88 patients (77.8%) while only 23 of those (26.1%) had bilateral hip pain. Painful hips had a statistically significant higher mean alpha angle than asymptomatic hips (69.9° vs 63.1°, p <
0.001). Hips with an alpha angle of more than 60° had an odds ratio of being painful of 2.59 (95% confidence interval 1.32 to 5.08, p = 0.006) compared with those with an alpha angle of less than 60°. Of the 201 hips with a cam-impingement deformity 42% (84) also had a pincer deformity. Most patients with cam-type femoroacetabular impingement had bilateral deformities and there was an associated acetabular deformity in 84 of 201 patients (42%). This information is important in order to define the natural history of these deformities, and to determine treatment.
We have developed a new tensor for total knee replacements which is designed to assist with soft-tissue balancing throughout the full range of movement with a reduced patellofemoral joint. Using this tensor in 40 patients with osteoarthritis we compared the intra-operative joint gap in cruciate-retaining and posterior-stabilised total knee replacements at 0°, 10°, 45°, 90° and 135° of flexion, with the patella both everted and reduced. While the measurement of the joint gap with a reduced patella in posterior-stabilised knees increased from extension to flexion, it remained constant for cruciate-retaining joints throughout a full range of movement. The joint gaps at deep knee flexion were significantly smaller for both types of prosthetic knee when the patellofemoral joint was reduced (p <
0.05).
We describe 129 consecutive revision total hip replacements using a Charnley-Kerboull femoral component of standard length with impaction allografting. The mean follow-up was 8.2 years (2 to 16). Additionally, extramedullary reinforcement was performed using struts of cortical allograft in 49 hips and cerclage wires in 30. There was one intra-operative fracture of the femur but none later. Two femoral components subsided by 5 mm and 8 mm respectively, and were considered to be radiological failures. No further revision of a femoral component was required. The rate of survival of the femoral component at nine years, using radiological failure as the endpoint, was 98%. Our study showed that impaction grafting in association with a Charnley-Kerboull femoral component has a low rate of subsidence. Reconstruction of deficiencies of distal bone with struts of cortical allograft appeared to be an efficient way of preventing postoperative femoral fracture for up to 16 years.
Due to economic constraints, it has been suggested that joint replacement patients can be followed up in primary care. There are clinical, ethical and academic reasons why we must ensure that our joint replacements are appropriately clinically and radiologically followed up to minimise complications. This Editorial discusses this.
We reviewed the long-term results at ten to 12 years of 118 total hip replacements in 109 patients using a second-generation hemispherical cementless acetabular component (Reflection) designed to address the problem of backside wear. Five patients (five hips) died and six patients (seven hips) were lost to follow-up. The remaining 98 patients (106 hips) had a mean age of 62.9 years (34.0 to 86.2) A rate of revision for aseptic loosening of 0.9%, and predictable results were found with respect to radiological evidence of fixation, lack of pain, walking ability, range of movement and function. One component was revised for aseptic loosening, and of the 101 hips (95.2%) that did not have a revision, minor osteolytic lesions of the pelvis were seen in six (5.9%). Kaplan-Meier survival analysis for the total cohort of 118 hips revealed a 96.4% survival at both ten (95% confidence interval 90 to 98) and 12 years (95% confidence interval 86 to 98).
This article considers some of the problems of the interpretation of information from other national arthroplasty registers when setting up a new register. In order for the most useful information to be available from registers much international co-operation is required between all those responsible for the design of registers as well as those who gather, assess and publish the data.
Bone surface strains were measured in cadaver femora during loading prior to and after resurfacing of the hip and total hip replacement using an uncemented, tapered femoral component. In vitro loading simulated the single-leg stance phase during walking. Strains were measured on the medial and the lateral sides of the proximal aspect and the mid-diaphysis of the femur. Bone surface strains following femoral resurfacing were similar to those in the native femur, except for proximal shear strains, which were significantly less than those in the native femur. Proximomedial strains following total hip replacement were significantly less than those in the native and the resurfaced femur. These results are consistent with previous clinical evidence of bone loss after total hip replacement, and provide support for claims of bone preservation after resurfacing arthroplasty of the hip.
The first 325 Exeter Universal stems (309 patients) implanted at the originating centre were inserted between March 1988 and February 1990 by a group of surgeons with differing experience. In this report we describe the clinical and radiological results at a mean of 15.7 years (14.7 to 17.3) after operation with no loss to follow-up. There were 97 patients (108 hips) with replacements still in situ and 31 (31 hips) who had undergone a further procedure. With an endpoint of revision for aseptic loosening, the survivorship at 17 years was 100% and 90.4% for the femoral and acetabular component, respectively. The mean Merle D’Aubigné and Postel scores at review were 5.4 (
