The April 2023 Hip & Pelvis Roundup. 360. looks at: Do technical errors determine outcomes of operatively managed femoral neck fractures in younger adults?; Single-stage or two-stage revision for hip prosthetic joint infection (INFORM); Fixation better than revision in type B periprosthetic fractures of taper slip stems; Can you maximize femoral head size at the expense of liner thickness?; Plasma D-dimer for periprosthetic joint infection?; How important is in vivo oxidation?;
We reviewed a consecutive series of 241 uncemented, porous-coated anatomic (PCA) hip replacements at an average follow-up of five years (2 to 9). Of these, 32 had failed (13%), 26 at the acetabular component (11%) and six at the femoral component (2%). Acetabular failure was associated with local osteolysis and excessive polyethylene wear in 20 cases: in these histological examination showed giant macrophages incorporating numerous particles of high-density polyethylene. The femoral failures were related to a poor intramedullary fit with subsequent subsidence. Using the recommendation for revision as the end point, the cumulative survival rate for prostheses was 91% at six years (95% CI +/- 6%), 73% (+/- 11%) at seven years, and 57% (+/- 20%) at eight years. The result of uncemented PCA hip replacement is satisfactory up to six years, but then increasing failure of the acetabular component appears to be due to polyethylene wear, leading to osteolysis, loosening and component migration. At first, failure is often asymptomatic; routine follow-up of uncemented hip replacement is essential, especially after five years.
The purpose of this study was to determine the biological effects of the elastic modulus of the femoral stem in canine hip arthroplasty. Cementless total hip arthroplasty was performed in 12 dogs, six had a low elastic modulus polyacetal resin stem and six had a high modulus stainless steel stem. The components were otherwise similar. At six and 12 months after operation, radiographic and histomorphometric analysis showed that those with steel implants had more cortical porosity than did the other group (p less than 0.01). We suggest that the elastic modulus of the implant is an important factor in controlling cortical bone resorption. A low modulus femoral prosthesis can significantly decrease bone resorption which might otherwise eventually lead to implant failure.
The February 2023 Hip & Pelvis Roundup. 360. looks at:
We performed 114 consecutive primary total hip arthroplasties with a cementless expansion acetabular component in 101 patients for advanced osteonecrosis of the femoral head. The mean age of the patients at surgery was 51 years (36 to 62) and the mean length of follow-up was 110 months (84 to 129). The mean pre-operative Harris hip score of 47 points improved to 93 points at final follow-up. The polyethylene liner was exchanged in two hips during this period and one broken acetabular component was revised. The mean linear wear rate of polyethylene was 0.07 mm/year and peri-acetabular osteolysis was seen in two hips (1.9%). Kaplan-Meier analysis indicated that the survival of the acetabular component without revision was 97.8% (95% confidence interval 0.956 to 1.000) at ten years. Our study has shown that the results of THA with a cementless expansion acetabular component and an alumina-polyethylene bearing surface are good.
The June 2023 Hip & Pelvis Roundup. 360. looks at: Machine learning to identify surgical candidates for hip and knee arthroplasty: a viable option?; Poor outcome after debridement and implant retention; Can you cement polyethylene liners into well-fixed acetabular shells in hip revision?; Revision stem in primary arthroplasties: the Exeter 44/0 125 mm stem; Depression and anxiety: could they be linked to infection?; Does where you live affect your outcomes after hip and knee arthroplasties?; Racial disparities in outcomes after
The December 2022 Hip & Pelvis Roundup. 360. looks at: Fix and replace: simultaneous fracture fixation and hip arthroplasty for acetabular fractures in older patients; Is the revision rate for femoral neck fracture lower for
The February 2024 Trauma Roundup. 360. looks at: Posterior malleolus fractures: what about medium-sized fragments?; Acute or delayed
We studied the effect of surgical experience on the dislocation rate after 4230 primary total hip arthroplasties (THAs) all performed using the posterior approach at three orthopaedic centres at major county hospitals. There were 129 postoperative (3%) dislocations. Twice the number of dislocations were registered for inexperienced surgeons as for their more experienced colleagues. This frequency of dislocation levelled off with increasing numbers of operations and remained constant after approximately 30. For every ten primary THAs performed annually, the risk of dislocation decreased by 50%.
We have reviewed 97 consecutive primary hip replacements with a cemented femoral component and a porous-ingrowth acetabular component at a minimum five-year follow-up (average 6.5 years). The average Harris hip score was 93, and 85 hips had no pain or only slight pain. There had been no deterioration in the results since the two-year follow-up. The hybrid hip is successful for up to eight years and appears to be suitable for many patients. Long-term femoral fixation has been shown to improve with second-generation cementing techniques and in this series was excellent with third-generation techniques, in that only one stem was revised for loosening. No cementless acetabular component was revised for loosening.
We implanted 203 smooth-stemmed femoral components before January 1988. The femoral component used was anatomically shaped, fluted and made of titanium. Thirty-two hips were revised due to mid-thigh pain, and the femoral implant was found to be loose in all. In the 157 patients with a two-year follow-up, the Merle d'Aubigne and pain scores for completely cementless arthroplasties were similar to those for hybrid prostheses (cemented acetabular cup and cementless femoral stem). Of the 145 cases with two-year radiographic follow-up, 59 had extensive radiolucencies and 22 were unstable. The five-year cumulative survival rate was 77%. Implantation of this stem should be restricted to patients in whom cement fixation is contra-indicated.
We assessed wound, air and operative field contamination at 50 total hip operations, performed in a zonal ventilation system. Theatre staff wore either a specially designed polypropylene non-woven coverall or conventional cotton shirt and trousers. The surgeons wore partially impermeable operating gowns. The polypropylene coverall was associated with significantly lower air and wound counts. The coverall was warmer than cotton but judged to be acceptable. The combined use of zonal ventilation and the coverall achieved ultra-clean air conditions.
Fifty-nine cases of trochanteric wire revision following hip arthroplasty with trochanteric osteotomy and reattachment were identified and their outcome was studied. Two were infected and were excluded. Five were revised for instability: four became stable while one continued to have persistent dislocation. Fifty-two were revised for pain, 36 by removal of the trochanteric wire and 16 by reattachment of the greater trochanter. Successful relief of pain was obtained in less than half the cases. There was no difference in the incidence of back pain, wiring technique, trochanteric advancement, previous surgery to the same hip, trochanteric size or the pattern of wire breakage in the successfully treated group and the unsuccessful group. Neither was the removal of intact wire from a united trochanter any more certain of relieving pain than removal of broken wire from an un-united trochanter. Six patients later required revision for loosening or infection. These results indicate the need for full radiological and haematological investigation before exploration of the greater trochanter. At exploration for pain the wires should simply be removed as we could show no successful union after late reattachment of the trochanter in the absence of instability.
We examined 59 cemented high density polyethylene sockets removed at revision hip arthroplasty. Of these 19 showed areas of wear between the outside of the socket and the acetabular bone. This was associated with lack of acrylic cement in those areas and was also related to the depth of the wear on the articulating surface of the socket. It is suggested that, in some cases, changes at the bone-cement junction are secondary to socket loosening and abrasion against the bone of the acetabulum, rather than to particles migrating from the metal-polyethylene interface. It is therefore important that impingement of the neck of the femoral stem on the edge of the cup be avoided and that, when the socket is inserted, it is not in direct contact with the bone.
