A prospective study of 276 TKA's performed in patients with valgus knee deformity ≥ 10° using a Modified Surgical Technique. Bone cuts were used to balance the valgus knee and soft tissue release was confined to the postero-lateral capsule in severe deformity. The aim was to restore a “functional mechanical axis” as opposed to a “neutral” mechanical axis. All surgeries were performed between Jan2003 and Apr2007, under the care of a single surgeon using an LCS rotating platform. All patients had full length radiographs and outcome scores collected prospectively. The mean coronal alignment of the lower limb was corrected from 15.9°(10-45°) to 3.8°. 94% patients had their coronal alignment restored to = 7°. Sixteen knees with postoperative valgus ≥8° were analysed as a separate group. The mechanical axis deviation was corrected from 52.3mm to 8.8mm. The distal femoral cut was made at 5° valgus in 131 knees(47.5%), 6° in 111 knees(40.2%) and 7° in 24 knees(8.7%).78 knees(28%) were balanced only with bone cuts. 198 knees(72%) had release of posterolateral capsule. 16 knees(5.8%) also had release of IT band. Lateral patellar release was performed in 39 knees (14%) and 23 knees had patella contouring. 93%knees had central patello-femoral alignment postoperatively. One spinout was managed by closed reduction and a second patient had revision of tibial tray for collapse. Patellar subluxation occurred in two patients. The oxford knee score and the American Knee Society clinical score improved from 48.5 to 26 and 21.04 to 86.03 respectively.MATERIALS AND METHODS
RESULTS
We report the result of 46 patients (30 female, 16 male) with periprosthetic femoral fractures who underwent insertion of the Kent Hip Prosthesis. Average age was 73 years (range 43–96years) and follow-up ranged from one to seven years (average, 4 years). The primary implants involved were as follows: Charnley (26), Austin Moore (6), Howse (5), Custom (4), Exeter (1), DHS (1), Thompson (1) and Richards (1). Average time to fracture from insertion of the primary implant ranged from 3 weeks to 20 years (average, 8 years). Forty cases were post-primary implant fractures (38 traumatic, 2 atraumatic) and 6 occurred intraoperatively. Using the Johanssen classification there were 12 type I, 30 type II and two type III fractures. Of the 46 cases, prior to fracture, 42 were living in their own home, 24 were mobile unaided and 20 had thigh and/or groin pain. Thirty-two had a loose stem and/or cup assessed at the time of surgery. Operating time was on average 143 mins (65–235mins). At latest follow-up, 43 were living in their own home, 5 were walking unaided and 10 had ongoing pain. In 34 cases complete union was achieved. There were no cases on non-union. Three patients required revision surgery for broken stems. Three patients sustained wound infections and there were six posterior dislocations. All of the complications were treated satisfactorily. We conclude that the Kent Hip Prosthesis is a useful option in the management of periprosthetic femoral fractures.
In Musgrave Park Hospital, Belfast, younger patients requiring THR were treated by custom-made titanium alloy femoral prosthesis. The identifit hips, which were used initially, were intraoperatively customised by preparing a silicon mould of the endosteal cavity and immediate computer assisted fabrication. The Xpress hips used measurements from preoperative marker x-rays allowing creation of templates and subsequent computer analysis to mill a stem prior to surgery. 7 identifit and 51 Xpress primary uncemented custom THRs were inserted in 50 patients between May 92 and June 96. The average age for the indentifit cases was 47 years (range 24–72) and the Xpress cases 39 years (range 23–51). The Xpress cases were followed up to an average of 47 months (range 12–74 months) and identifit cases to an average of 59 months (range 14–77 months). The indications for arthroplasty were osteoarthrosis in 15 hips, CDH in 14, dysplasia in 11, AVN in 4, rheumatoid arthritis in 3 and other diagnosis in 11. Clinical assessments were made using the Oxford score and the Modified Harris Hip score. The postoperative radiographs were evaluated for subsidence of the prosthesis; and adaptive osseous changes like osteolysis, hypertrophic cortical remodelling, sclerotic radiolucent line formation around the prosthesis and formation of a bone pedestal below the tip of the prosthesis. The average post-op Oxford hip score for those patients not revised was 32.5 /60 (range 12–51). 16 of the 51 Xpress hips underwent revision and 2 were awaiting revision, which is a failure rate of 35.3%. Of the identifit hips 1 out of the 7 was revised (14.3%). Overall 32.8% was the rate of failure. The average duration from primary operation to revision was 47 months for Xpress hips and 90 months for the identifit hips. Of the Xpress hips, revision was done for acetabular component in 1, femoral component in 4, both components in 1, acetabular liner + femoral head in 1 and acetabular liner + femoral component in 9. The 1 revision in the identifit hip was for recurrent dislocation. The reasons for revision in the Xpress hips were dislocation in 2 cases, loose femoral component in 13 cases and infection in 1. Average subsidence of the femoral component was 6mm (range 0–25.9) and this did not have significant correlation with predicting outcome. Pedestal formation (intramedullary formation of bone beneath the tip of the femoral stem) was seen in 87%, sclerotic rediolucent lines were seen in 64%, osteolysis was found in 31% and hypertrophic cortical remodelling was seen in 31%. These also did not reach significance in predicting outcome. Thus even though the idea of an uncemented custom THR is attractive, especially in the younger age group, the failure rate was found to be unacceptably high. On the basis of these data we have discontinued the use of this custom made non-porous uncemented femoral prosthesis.
