Silastic flexible hinge implant arthroplasty of the great toe for hallux rigidus: A retrospective analysis
S Jain, B Banerjee
hallux, replacement, silastic
S Jain, B Banerjee. Silastic flexible hinge implant arthroplasty of the great toe for hallux rigidus: A retrospective analysis. The Internet Journal of Orthopedic Surgery. 2007 Volume 9 Number 2.
The outcomes in 65 patients with 76-silastic flexible hinge (two-stem) metatarsophalangeal joint implant arthroplasty for hallux rigidus were studied retrospectively. The mean age of patients at the time of surgery was 56 years (26-86) and mean follow-up was 6 years (2-11). Overall success rate on subjective assessment was 80%. Fifty-five (85%) patients reported good pain relief after the operation. Average AOFAS score improved from 30 (range 20-40) before the operation to 70 (range 60-80) at one year after the operation. Although follow-up radiographs demonstrated variable amounts of lysis around 10% of the silastic implants (8 patients), this deterioration did not correlate with reduction in patient satisfaction. Therefore silastic metatarsophalangeal joint arthroplasty should still be considered as an option in selected patients with end-stage hallux rigidus where other total joint arthroplasty or arthrodesis is not feasible.
Arthrodesis is still the preferred treatment for end-stage hallux rigidus in young and active patients. Silicone implant arthroplasty of the great toe was first described by Swanson et al in 1979(10). Over the years however, it has fallen into disrepute due to conflicting reports of silicone-related synovitis and bone lysis (2,10). This has led to other forms of total joint replacement becoming more popular.
The objective of this retrospective study was to analyse medium to long-term clinical outcomes and satisfaction of patients with silastic flexible hinge (two-stem) implant arthroplasty of the great toe metatarsophalangeal joint.
Material And Methods
Sixty-five patients who underwent a silastic flexible hinge implant arthroplasty (Wright Medical Technology, Inc.) of the first metatarsophalangeal joint for hallux rigidus between May 1996 and December 2004 were evaluated retrospectively. A total of 76 silastic prostheses were implanted (54 unilateral and 11 bilateral). The group comprised 25 males and 40 females with an average age 56 years (26-86). Co-morbidities included non-insulin dependent diabetes (three patients), hypertension (three patients) and moderately severe rheumatoid arthritis (three patients). Most of the patients in our study group were within average BMI range (20-25). All the patients in the working age group were in predominantly sedentary jobs, as those doing manual work were advised against this procedure. Twelve patients (18%) had had previous chevron osteotomy with bunionectomy for hallux valgus. All patients completed satisfaction questionnaire, VAS and (American Orthopaedic & Ankle Society Score) AOFAS pre-operatively.
Surgeons of similar seniority and experience performed the operations, and most of the cases were operated as day-case procedures. The procedures were all performed through a dorso-medial incision under tourniquet control. Bunionectomy, cheilectomy and medial capsular reefing were carried out in all the cases. Titanium grommets (collars) were used in 40 (52%) cases. Postoperatively, all patients were advised to remain non-weight bearing for the first 2 weeks until the sutures were removed. They were then put in a plaster shoe for a further 4 weeks and were allowed “heel-walking” only. After 6 weeks, they were allowed unprotected weight bearing and normal shoes.
All patients were then routinely followed up at 6 months, 12 months and yearly thereafter, with radiographs at each visit.
The average time of follow-up was 6 years (2-11). At final follow up we repeated assessment of overall subjective satisfaction, Visual Analogue Scale (VAS) for pain, and AOFAS. We also graded the radiological appearance at final follow-up, in terms of great toe alignment; implant position and peri-prosthetic bone lysis.
Overall success rate on subjective assessment was 80%. Fifty-five (85%) patients reported good pain relief after the operation with an average Visual Analogue Scale of 2.5 (range 0-5) as compared to pre-operative average score of 5.5 (range 4-7), which was found to be statistically significant (p < 0.001).
All patients experienced a subjective improvement in range of movement in the joint. Post-operatively, the average flexion was 11° (range 5-20°) and extension 20° (range 10-30°). Although none of the patients reported difficulty in walking or slow running, most patients reported limitation of recreational activities. The average AOFAS score improved from 30 (range 20-40) before the operation to 70 (range 60-80) at 1 year after the operation (p=0.0001). The scores remained unchanged thereafter.
The radiographs were deemed satisfactory if they showed full correction of the deformity; good implant position and no intra-operative fractures. The postoperative radiograph was satisfactory in 46 (70%) patients. Although follow-up radiographs demonstrated variable amounts of lysis (fig 1) around 10% of the silastic implants (8 patients), this deterioration did not correlate with reduction in patient satisfaction.
Titanium grommets (collars) were used in 40 (52%) cases. In 2 patients (3%) with bilateral first metatarsophalangeal joint replacements, a grommet was used only on one side. In both these cases, there were features of early lysis around the implant on the side without the grommet. This is thought to occur due to the sharp bone edges rubbing against the implant in absence of protective titanium grommet. However, there was no difference in AOFAS scores, VAS for pain and range of movement in the two groups.
Six patients (9%) complained of persisting mild to moderate pain and swelling in the joint. Two patients (3%) felt that the operation had not adequately corrected the great toe deformity (fig 2), but they were satisfied with their improved level of function. All the above 8 patients declined to have the joint arthrodesed. Two patients (3%) had deep infection requiring implant removal.
Arthrodesis is still the preferred treatment for end-stage hallux rigidus in young and active patients. Silicone implant arthroplasty of the great toe was first described in 1979 by
In our series, most patients reported good pain relief at 6 months after the operation, and improved function in activities of daily living and work. All patients reported no difficulty in walking or slow running although there was some limitation of recreational activity.
Single-stemmed silastic MTP arthroplasties have been abandoned in many centres because of short-term complications, and have been superseded by hinged implants.
We conclude that silastic flexible hinge (two-stem) first metatarsophalangeal joint replacement is an effective treatment for end stage hallux rigidus, which not only provides long- term pain relief but also a satisfactory range of movement. Therefore it should still be considered as an option in selected older patients where other total joint replacement or arthrodesis is not feasible. We recommend a long-term large multicentre study to evaluate this further.
Mr. S.A. Jain 1 St. Thomas Close Sutton Coldfield B75 7QJ UK E-mail: firstname.lastname@example.org Tel: +44 121 2402256