NB This page is from the 2005 Hyperbook.
Last evidence check June 2005 but no significant revision since September 2004.
Osteoarthritis presents less commonly in the ankle than in other lower limb joints. This is, perhaps, surprising, as the stresses in the ankle are high and the joint surfaces area lower than in other joints. In the ankle OA is often, but not always, secondary.
Most patients present with pain in the ankle. Sometimes it is described in the posterior foot or midfoot, or up the leg. Radiation above the mid-tibia should make one suspect proximal problems. Some patients complain the ankle locks or gives way, which may be due to a loose body but usually just represents attacks of severe pain with reflex inhibition of the supporting muscles. Midfoot pain may also arise from OA of the talonavicular, calcaneocuboid or lesser tarsal joints.
It is important to find out what has already been tried. It is quite common to see a patient referred for an ankle fusion or replacement who is not even taking regular analgesics. There may be several non-surgical options to explore, or the patient may have tried all these and needs counselling about definitive surgery.
As noted above, patients with arthritic ankles often have other joints involved, which may affect the surgical option and likely outcomes. Others have had a severe or repeated injury or infection, which may have affected their soft tissue envelope or left troublesome scars or nerve problems. A history of deep infection will restrict definitive surgical reconstruction possibilities – almost certainly to a fusion, possibly with an Ilizarov or other external frame.
Cigarette smoking increases the risks of ankle non-union by at least three times, and may affect wound healing after any procedure.
The main investigation is a standing AP and lateral radiograph of the ankle. This will allow assessment of remaining joint space, spurs and loose bodies. If there is malalignment, a standing hindfoot alignment view will show at which level – ankle, subtalar or both – the malalignment is occurring.
Where there is loss of bone stock or complex anatomy post trauma or infection a CT can be helpful
MR will show joint surface lesions such as osteochondritis dissecans, and soft tissue abnormalities including infection and sinuses.
If there is osteonecrosis, usually of the talus, MR will show the extent of the abnormality, which will help surgical planning, but an isotope bone scan is required to show how much revascularisation has occurred.
Standard blood tests may be required to rule out inflammatory arthropathy, gout or residual infection.
After history, physical examination and appropriate investigation, it should be possible to decide whether
If surgery is appropriate:
Most patients presenting with arthritic ankles can be managed with simple measures:
Steroid injections are often helpful on an empirical basis, although there is no good evidence base for their use and in other joints they may not be much better than placebo.
Hyaluronan supplementation injections have been described in other joints. In the knee the evidence suggests a modest effect in moderately severe arthritis but not in end stage disease. There have been anecdotal reports in the ankle.
Surgery is an option where non-surgical treatment has failed to control the patient’s symptoms and they are seriously affecting the patient’s activities of daily living, work and sleep.
Can be useful where the joint is reasonably well preserved, especially if the main problem is impingement from synovitis or spurs, or loose bodies. Arthroscopic debridement for impingement had a 75% success rate at 5 years in the presence of spurs, but only 50% with loss of joint space (Tol et al 2001). Ogilvie-Harris et al (1995) found limited improvement in about 2/3 of 27 patients.
An Ilizarov external fixation frame is applied across the ankle and a distraction force applied. The frame is articulated to allow active joint movement. Useful improvement in pain and movement have been reported (Marijnissen et al 2003). Weightbearing radiographs suggest that joint cartilage thickness is regenerated. This technique requires complex apparatus and specialised staff.
Distal tibial malalignment may be secondary to injury, intra-or extra-articular or involving the growth plate; or it may be an intrinsic deformity. Realignment is an option where the joint is reasonably well preserved – an arthroscopy may be required to check. Where the joint is severely arthritic an arthrodesis or replacement is more appropriate.
Until recently this was the only real option for end-stage ankle arthritis of whatever aetiology. The traditional British method was that of Charnley with a destructive anterior transverse approach and external fixation with a semi-stable frame. This had a high incidence of infection and non-union. Arthrodesis is now normally carried out with an open or arthroscopic surgical technique, and fixation with screws, plates or an intramedullary nail. Arthroscopic surgery does less soft-tissue damage. Early studies suggested a high rate of non-union, but in experienced hands it probably results in quicker and less complicated union of the fusion (O’Brien et al 1999). However, it is difficult in very stiff ankles with large osteophytes, or where there is significant deformity. Long-term studies show OA developing in adjacent joints, although not always symptomatic, and of course this might have happened anyway without the fusion.
Has been around for over 30 years. However, early prostheses did not reproduce the biomechanics of the ankle well and had a very high failure rate. Second-generation prostheses from the late 1980s onward introduced improved engineering, often with three components. 10-20 year results are now being published (Kofoed 2004, Buechel et al 2004), indicating success in over 90% of patients. However, these are the series of the designers of the various prostheses, and further results from the “real world” may not be quite so optimistic. The Wrightington series (Wood and Deakin 2003) is a realistic and critical account with 5-8 year follow-up and 92% 5-year success. Results in OA and RA are similar (Kofoed 2004, 1998; Wood and Deakin 2003). Ankle prostheses also seem to be best uncemented; the long term results of the STAR ankle have been significantly better in the uncemented design (Kofoed 2004). Like all joint replacements, failure occurs and may require revision replacement or fusion. The failure rate for revision arthroplasty is high and most patients will be better revised to a tibiotalocalcaneal fusion.
It is only appropriate to compare fusion and replacement for patients without major deformity, infection, bone loss or neuropathy – these would only be candidates for fusion. However, there have been no direct comparisons of replacement and fusion in patients in whom both would be an option. In addition, outcome measures in single-procedure series are so varied that it is difficult to compare them.
As might be expected, ankle fusion affects the range of motion and kinematics more than does replacement, and certain designs are closer to normal than others (Valderrabano et al 2004a,b). Gait analysis is much closer to normal in replaced than in fused ankles (Butcher et al 2004). Hence it is plausible that ankle replacements would place less stress on other joints, both in the tarsus and proximally. Nevertheless, this requires clinical confirmation.
A study of patients 20 years after ankle fusion (Fuchs et al 2003) reported reduced SF-36 pain, physical functioning and emotional disturbance scores, and moderate Olerud ankle scores. Most patients wore customised footwear, but few had walking aids. All but one had returned to work. There was significant progressive OA in the other hindfoot joints. The surgery included more external fixation than would be expected in a current population. Another study (Buchner et al 2003) reported little or no pain and restriction of activity in 92% of patients at an average of 9.3 years follow-up. An independent study of fusion in OA (Anderson et al 2002) found that the true fusion rate was 80-89% but the clinical and radiological outcomes were not the same. The longest follow-up of arthroscopic arthrodesis (Glick et al 1996) reported a 97% fusion rate at an average of 8years follow-up, with 88% good or excellent results. In rheumatoid disease, Felix et al (1998) reported union in 96% of 26 ankles at 2-8 year follow-up, and no pain 19.
These studies tend to highlight need for revision as the main outcome measure. At 12 years, the survivorship of the current cementless Buechel-Pappas implant was 92% (Buechel et al 2004), but clinical results were presented only as excellent 88%, good 5%, poor 7% (75 patients). Twelve-year survival for the STAR ankle was 95%, with a mean Kofoed ankle score of 91.7/100. The long-term survival rate is based on small numbers in each study. The Wrightington series (Wood and Deakin 2003), although shorter in follow-up (2-8.5 years), is also worthy of study, as it is very large, meticulously critical and realistic. The 5-year survival rate was 92.7%. The mean AOFAS hindfoot score for pain improved from 0/40 pre-operatively to 35 at final follow-up and the functional score from 28/60 to 35. Complications and the learning curve are detailed. None of these studies comment on OA in adjacent joints.
There is not enough data to indicate whether fusion or replacement is to be preferred for patients in whom either procedure would be an option. At about 10 years clinical success rates appear similar; possibly the onset of OA in other joints reduces the success of fusion thereafter. The improved kinematics of ankle replacement probably reduce the wear on adjacent joints, and this could be important, particularly in patients with multiple joint pathology. The improved range of movement is anecdotally useful to patients, but there are no comparative studies.