Introduction/Purpose

Total ankle replacement (TAR) success has improved since first-generation implants, but patient satisfaction continues to be less than knee and hip replacements. Little is known about variations in distal tibia anatomy between genders and across ethnicities; therefore it is unclear the extent to which current TAR prostheses accommodate variability in patient size and shape. This study quantified distal tibia morphometrics relevant to TAR design, and assessed differences between ethnicities and genders. The hypotheses were: (1) The anterior-posterior (AP) location of the dwell point of the tibia is centralized; (2) The sagittal radius of curvature of the tibial articulation increases with bone size; (3) Differences in dwell point location or sagittal radii between genders and ethnicities can be attributed to size differences between those populations.

Material: 100 consecutively performed Total Ankle Arthroplasties (TAA) of the Mobility design carried out at Schultess Clinic Zurich and 100 from Wrightington Hospital Wigan were entered into the study. The male: female ratio was 1:1. Age 62 (range 24 to 95 years). The diagnosis was primary OA (59%), OA resulting from a major injury in the past (20%) and rheumatoid arthritis (21%). We considered more than 20 degrees varus or valgus to be a contraindication to TAA.

Methods: The Mobility TAA is three component, cobalt chrome uncemented design. The tibial component has a stem and the talar component has two fins for secure bony incorporation. At the time of TAA ancillary procedures such as gastrocnemius lengthening were performed if required.

Results: The follow-up was 36 months (24 to 50). The most frequently performed ancillary procedure was gastro-soleus lengthening and this was carried out in 20% of cases. Osteotomy of os calcis and talo-navicular or other hindfoot fusion was performed in approximately 8%. The severity of pain was measured on the visual analogue scale before and at follow-up and this improved from 8.5 to 1.6. The average range of motion measured radiographically improved from 25 deg to 30 deg. The most frequent persistent complaint was that of occasional troublesome antero-medial pain. 92% patients were satisfied with the outcome. Complications were 6% intra-operative malleolar fractures. These did not lead to long term problems. Delayed wound healing occurred in 4% but all healed fully by three months. Late medial malleolar fractures occurred in 2%. Early infection occurred in one patient and was successfully treated by washout and antibiotics. Revision to fusion or change of tibilal and/or talar implant was required in 2.5% (5 patients) due to aseptic loosening and a technical error in one further patient treated three years ago led to subluxation of the insert. This was changed for an 11mm insert with a successful outcome to present time.

Conclusion: These results are an improvement on those acheived by the same surgeons prior to this study using other types of implant. We believe this is due to improved instrumentation and implant design and a better understanding of the indications particularly the need to be very cautious in recommending replacement to patients with severe varus or valgus deformities.

For many decades ankle fusion has been the only option for treatment of symptomatic osteoarthritis of the ankle joint. From the late 60’s on the crusade of joint replacement for hip and knee led to successful functional restoration for severe destruction of these joints. Because of a lack of understanding the biomechanical principals of the ankle a similar approach in reconstructing the ankle arthritis was doomed to fail. On the other side very good functional outcome after fusion of the ankle seemed to make needless further development. Although first encouraging results with non-constrained designs and cementless fixation were obtained in mid-late 70’s a wider acceptance within the orthopaedic society was found only almost 20 years later whereas today many surgeons wouldn’t give up the ankle arthroplasty for several indications. Despite good and very good midterm results we still need to understand limits and further develop operative techniques especially soft-tissue balancing.

In our institution we have been using TAR since 1995 on a regular basis and by now overlook a total of almost 400 TAR’s. The experience with different designs (Agility, S.T.A.R. and Buechel-Pappas) led to the development of the Mobility-TAR in collaboration with two surgeons from England and the U.S. It is a 3-component TAR, non-constrained. As a unique feature the instrumentation allows an accurate centring of the implants both in the frontal and the saggital plane. In a prospective trial in Wrightington and Zurich we clinically and radiographically evaluate the outcome. The first 42 cases in Zurich with a follow-up of more than 1 year showed a significant pain reduction from av. 8.1 on a visual analogue scale to av. 1.4 after one year. The ROM assessed radiographically could be improved from 26° preoperatively to 33° after one year. We have seen 4 fractures/osteotomies of the medial malleolus and one neuropathy of the tibial nerve as intraoperative complications. Postoperative complications included two superficial wound healing problems, one deep infection and finally two stress fractures of the medial malleolus. One case had to be revised because of aseptic loosening after 6 months. All but one of the first 42 patients would undergo the same procedure again.

The first results are encouraging because of good overall results with significant pain reduction and good ROM combined with only few complications.

Purpose: Results of basal metatarsal osteotomy are generally unpredictable. We studied the very oblique BRT osteotomy with preservation of the proximal hinge and fixation using a threaded-head screw. We now use this technique as a routine procedure.

Material: From 1999 to 2000, 125 metatarsal osteotomies were performed on 93 feet in 77 patients (mean age 55 years). Indications were metatarsalgia alone in 34 feet, associated with another osteotomy for 21 feet, iatrogenic for 18 feet, and anterior pes cavus for 20 feet.

Method: The incision was dorsal (3 medial metatarsals) or medial for M1 or lateral for M5. The osteotomy was very oblique (60°), with removal of a thin wedge (max 3 mm) except for M1 or in case of pes cavus. The proximoplantar hinge was carefully preserved. The osteotomy was limited to the strict clinical needs and determined on the false lateral view. All patients were reviewed at six months and one year after surgery (mean follow-up 11 months).

Results: The fixation was solid allowing weight bearing at 15 days. Metatarso-phalangeal motion was preserved. There was no secondary displacement but there were three cases with a ruptured hinge due to an insufficiently oblique osteotomy. At last follow-up there has been no transfer to neighbouring rows. For the pes cavus cases, the M1 osteotomy was associated with osteotomy of one or several lateral metatarsals in 13/20 feet in order to further raise the first metatarsal without risk of transfer metatarsalgia.

Discussion: The BRT osteotomy provides an unprecedented reliability for proximal osteotomy with elevation of the metatarsus. It is highly dependent however on clinical assessment, as for any basal osteotomy, although the false lateral view is quite useful. Excessive dorsal elevation must be avoided; secondary elevation is avoided due to the absence of secondary displacement. This osteotomy can be performed easily on all five metatarsals for pes cavus. It is often associated with distal treatment of claw toes. Its association with calcaneum osteotomy is useful for extra-articular treatment of pes cavus to preserve long-term function.

Conclusion: For the two indications metatarsalgia and pes cavus, the BRT osteotomy with elevation of the base is easy to perform, prevents secondary displacement, is precise, and preserves joint function. Precision depends almost totally on clinical evaluation. Results have been very encouraging. Finally, this osteotomy, which involves elevation of the base alone, is complementary to the Weil osteotomy which has specific indications for longitudinal harmonisation of the metatarsus.