Ingemar Ivarsson

Internal fixation versus total hip arthroplasty in the treatment of displaced femoral neck fractures. A prospective randomized study of 100 hips

100 patients 75 years or older, with displaced femoral neck fractures, were randomly assigned to osteosynthesis with two parallel and percutaneously inserted screws (Olmed) or total hip arthroplasty (Lubinus IP). Mean age was 84 (75-101) years, 74% were women and 45% had mental dysfunction. General complications were commoner in the arthroplasty group but the mortality rates did not differ. In the osteosynthesis group, fracture complications were seen in 27/50 hips. In the arthroplasty group, dislocation was the main complication and occurred in 11/50 cases. At 3 months and after 1 year, the Harris Hip Scores were significantly better in the arthroplasty group. When mental dysfunction was present, the dislocation rate after arthroplasty was 32%, whereas the reoperation rate after osteosynthesis was 5%. The opposite pattern of complications was found in patients with normal mental function, 12% versus 60%. The 2-year mortality rate among those with mental dysfunction was 26/45, compared to 7/55 of those with normal function (p < 0.001). We conclude that total hip arthroplasty should be considered for a displaced femoral neck fracture in old patients with normal mental function and high functional demands.

Revision of infected hip replacement: Two-stage procedure with a temporary gentamicin spacer

We revised 5 infected totally-replaced hips in 2 stages. At the first operation a gentamicin-loaded modelled cement spacer was inserted, and the definitive prosthesis was inserted 3-8 weeks later. 9-24 months after the last operation, there was a recurrent infection in 1 case. 2 of the patients could walk in the interval.

Effect of diclofenac on fixation of hydroxyapatite-coated implants. An experimental study

We studied the effect of non-steroidal anti-inflammatory drugs on the fixation of hydroxyapatite-coated implants. Cylindrical plugs of pure titanium, coated with hydroxyapatite (HA), were inserted into both femora of 10 adult rabbits, 5 of which received 7 daily doses of 30 mg diclofenac. Three weeks after implantation the interface strengths were measured by the pull-out test. The mean peak force for the diclofenac-treated group was 290 +/- 57 N compared with 369 +/- 37 N for the control group (p < 0.025). We conclude that the inhibitory effect of diclofenac on bone repair is not neutralised by HA-coating of an implant.

Stem loosening more common with ITH than Lubinus prosthesis : a 5-year clinical and radiographic follow-up of 142 patients

Out of a consecutive series of 169 cemented total hip arthroplasties, 77 Lubinus SP 2 and 65 ITH prostheses, were followed-up after 5 years with clinical and radiographic assessments. Radiolucencies were commoner around the ITH titanium stem than around the Lubinus cobalt-chrome stem. 6 of the ITH stems were considered as definitely loose, as compared to none of the Lubinus stems. Hitherto, 5 patients in the ITH group have had revisions and 2 need revision because of loosening. The poorer performance of the cemented ITH stem may be due to an unfavorable combination of design and material properties.

No difference in migration or wear between cemented low-profile cups and standard cups : A randomized radiostereographic study of 53 patients over 3 years

Background Minor design changes may cause major changes in implant performance. Thus, as part of a stepwise introduction of a new low-profile cup, we performed a randomized trial comparing it to a well-docu-mented standard cup. Patients and methods 60 patients, stratified according to sex, weight, and age, underwent cemented total hip arthroplasty using a Lubinus SP2 stem with ceramic head and were randomized to either the new low-profile Lubinus Flanged Anti-Luxation cup (FAL) or the Lubinus Standard Eccentric cup (Standard). 7 patients were excluded and 53 (28 FAL) were evaluated at 3, 6, 12, and 36 months postoperatively. Primary outcome variables, cup migration (MTPM), and wear (total 3-dimensional femoral head penetration) were measured with radiostereometry (RSA). Clinical outcome was evaluated with the western Ontario and McMaster osteoarthritis index (Womac) and the visual analog pain score (VAS). Results We found no difference in migration between the FAL and Standard cups. There was no difference in wear between the two cups and there was no correlation between wear and migration. 3 cups (2 FAL and 1 Standard) showed continuous migration of a magnitude that indicated an increased risk of early loosening. Clinical outcome was excellent, without any difference between the 2 groups.

Local bisphosphonate reduces migration and formation of radiolucent lines adjacent to cemented acetabular components

Aims Post‐operative migration of cemented acetabular components as measured by radiostereometric analysis (RSA) has a strong predictive power for late, aseptic loosening. Also, radiolucent lines predict late loosening. Migration has been reduced by systemic bisphosphonate treatment in randomised trials of hip and knee arthroplasty. Used as a local treatment, a higher local dose of bisphosphonate can be achieved without systemic exposure. We wished to see if this principle could be applied usefully in total hip arthroplasty (THA). Patients and Methods In this randomised placebo‐controlled, double‐blinded trial with 60 participants, we compressed gauze soaked in bisphosphonate solution (ibandronate) or saline against the acetabular bone bed immediately before cementing the acetabular component. RSA, classification of radiolucent lines, the Harris Hip Score (HHS) and the Western Ontario McMasters Universities Osteoarthritis Index (WOMAC) were carried out at three‐, six‐, 12‐, and 24‐month follow‐up. Results Migration of the cemented acetabular component relative to the pelvis was reduced by movement almost half in the ibandronate group, when measured as maximum total point or as movement of the femoral head (p = 0.001 and 0.004, respectively). Radiolucent lines after one year were classified as absent, partial or complete, and correlated with treatment (rho 0.37; p = 0.004). Only three of 30 patients in the ibandronate group had complete lines, compared with 13 of 28 in the placebo group (p = 0.002). There were no significant effects on HHS or WOMAC score. Conclusion Considering the power of RSA to predict loosening of cemented acetabular components, and the likelihood that radiolucent lines indicate risk of loosening, these data suggest that local treatment with a bisphosphonate can reduce the risk of late aseptic loosening.

Renal function after hip arthroplasty and isoxazolylpenicillin prophylaxis

Two different isoxazolylpenicillins (cloxacillin and dicloxacillin) were compared regarding impairment of renal function after total hip arthroplasty. 85 patients received dicloxacillin and 93 patients received cloxacillin as antibiotic prophylaxis. A total dose of 6 grams was given during a 36-hour period in doses of 1 gram pre-, per- and postoperatively. Creatinine in serum and beta 2-microglobulin in serum and urine were determined preoperatively and 2, 4, and 10 days after the operation. The dicloxacillin-treated patients had an increase in creatinine and beta 2-microglobulin in serum that was not seen in the cloxacillin group. The increase indicates a transient injury in the process of glomerular filtration. Although the increase was temporary and subclinical, a dose reduction is nevertheless recommended for older patients.

Initial stability of two different hip revision concepts : A biomechanical study

Two fundamentally different revision concepts, a standard stem cemented in a bed of firmly impacted morselized bone graft, and an uncemented long stem implanted with proximal bone grafting, were compared in terms of initial stability under torsional load immediately after implantation. A stem cemented without bone graft was used as a baseline reference. The stems were implanted in identically prepared composite femora inclined at 45° and loaded vertically. During 9 individual tests of each concept, the stems displaced into retroversion with no detectable axial displacement. At a load of 1000 N the average displacement in retroversion of the prosthetic head was 3.9° ± 2.6° for the uncemented long stem and 9.1° ± 2.6° for the stem cemented in impacted morselized bone graft (P < 0.001). Both revision concepts displaced rather dramatically compared to the stem cemented without bone grafting. The magnitude of displacement may indicate insufficient initial rotational stability of both concepts particularly with the stem cemented in impacted morselized bonegraft.