Degenerative Conditions and Osteonecrosis of the Foot and Ankle

Samuel B. Adams, MD

Andrew E. Hanselman, MD

Selene G. Parekh, MD, MBA, FAOA

Dr. Adams or an immediate family member is a member of a speakers’ bureau or has made paid presentations on behalf of Arthrex, Inc.; serves as a paid consultant to or is an employee of 4web, Exactech, Inc., Medshape, Orthofix, Inc., Regeneration Technologies, Inc., and Stryker; has stock or stock options held in Medshape; and serves as a board member, owner, officer, or committee member of the American Orthopaedic Foot and Ankle Society. Dr. Parekh or an immediate family member has received royalties from Arthrex, Inc., Integra, Orthohelix, Solana; is a member of a speakers’ bureau or has made paid presentations on behalf of Pacira; serves as a paid consultant to or is an employee of Additive orthopaedic, Arthrex, Inc., Integra, Pacira, Solana, Sonoma orthopaedics, Stryker, and Wright Medical Technology, Inc.; has stock or stock options held in Extremity medical, Invuity, Nextremity medical; has received research or institutional support from Biomet, Pacira; and serves as a board member, owner, officer, or committee member of the American Orthopaedic Association and the American Orthopaedic Foot and Ankle Society. Neither Dr. Hanselman nor any immediate family member has received anything of value from or has stock or stock options held in a commercial company or institution related directly or indirectly to the subject of this chapter.

ABSTRACT

Arthritis of the foot and ankle includes osteoarthritis, posttraumatic arthritis, inflammatory arthritis (ie, rheumatoid arthritis), secondary to osteonecrosis, among others. Unfortunately, modern medicine does not have a cure for any of these degenerative arthropathies, and therefore treatment is based on symptom relief through nonsurgical treatment or removal of the arthritis via fusion or replacement. Nonsurgical methods include NSAIDs, shoe wear modifications, and injections such as corticosteroids. Interestingly, the majority of the literature on degenerative conditions of the foot and ankle describes surgical treatment. Although there may be subtle treatment differences in certain instances, for the most part all types of arthritis are treated similarly in each part of the foot and ankle.

Keywords: ankle; arthritis; arthrodesis; avascular necrosis; foot; osteonecrosis

Ankle

Ankle arthritis can have a substantial impact on patient quality of life. In fact, ankle arthritis causes patients to take fewer total steps per day, take fewer high-intensity steps, and choose to walk at a slower walking speed compared with patients without ankle arthritis.¹ Unlike hip and knee osteoarthritis, ankle osteoarthritis is most commonly the result of trauma. Nonsurgical management, although not as successful as surgical management, can include bracing treatment and injections. In fact, the injection of hyaluronate at 3-weekly intervals in patients with moderate to severe unilateral ankle arthritis provided significant improvement in patient outcome and balance and reduced NSAID use at 6 months after injection.² However, another study using only a single hyaluronic acid injection found no difference in pain and patient outcomes compared with saline injection control patients.³ Other biologics have also been tried as a method to avoid surgery. In a recent study, three injections of platelet-rich plasma (PRP) were injected at 2-week intervals in 20 patients with varus ankle OA.⁴ The authors found significant improvement in pain and patient-reported outcomes out to 24 weeks (the study end point) without any adverse side effects. Despite some positive effect of intra-articular injections, there is no evidence that any treatment other than surgery changes the course of ankle arthritis.

Supramalleolar Osteotomy

Supramalleolar osteotomies are performed to realign the mechanical axis of patients with asymmetric varus or valgus arthritis and a preserved tibiotalar joint
surface. Varus arthritis is treated with a medial opening wedge tibial osteotomy. A fibular osteotomy may be needed for corrections >10°. Valgus arthritis is treated with a medial closing wedge osteotomy and an oblique fibular lengthening osteotomy. Alternatively, a tibial dome osteotomy is recommended for varus or valgus deformities greater than 15° due to excessive translation of the talus in opening wedge osteotomies and shortening of the tibia in closing wedge osteotomies.

A recent study demonstrated significantly improved AOFAS scores in 94 patients who underwent supramalleolar osteotomies for incongruent ankle arthritis at a mean follow-up of 3.6 months.⁵ Similarly, in another study of 35 patients with valgus ankle arthritis who underwent supramalleolar osteotomies, 91% of patients were able to avoid ankle replacement or ankle arthrodesis at a mean of 5 years.⁶ Other studies have demonstrated that the results of supramalleolar osteotomies are worse with congruent ankles and when degenerative changes in the medial gutter were present.⁵^,⁷

Although this technique is used for deformities originating from the ankle joint (ie, varus ankle from lateral ligamentous laxity), the authors prefer to perform supramalleolar osteotomies when the deformity originates from the tibia.

Distraction Arthroplasty

Although once popular, distraction arthroplasty is falling out of favor. It is an alternative option to ankle arthrodesis or arthroplasty in younger patients with arthritis. The principle behind this technique is mechanical unloading of the ankle joint, preservation of ankle motion, and potentially promoting cartilage repair. An external fixator is used while allowing motion at the ankle joint. A recent study on 25 patients who underwent this procedure at a mean of 30 months prior reported that 91% of patients had improved pain with the furthest out from surgery experiencing the best results.⁸ There was significant AOFAS score improvement. In another study, with a minimum of 5 years of follow-up, 55% of patients still had a native ankle joint and 45% had undergone either ankle arthrodesis or ankle arthroplasty.⁹ The authors concluded that ankle joint function declines over time after this procedure. Complications of distraction arthroplasty are mostly associated with the use of an external fixator, such as pin site infection, pin breakage, and osteomyelitis.

Arthrodesis

The traditional “benchmark” treatment for end-stage ankle arthritis that failed nonsurgical management was ankle arthrodesis. Ankle arthrodesis has been performed through open, mini-open, and arthroscopically assisted approaches with generally favorable union rates. One study compared the anterior and transfibular approaches and found no differences in AOFAS scores.¹⁰ The anterior approach had a longer time to fusion and a slightly higher nonunion rate, but these issues were not significant. However, if the transfibular approach is used, the fibula should be preserved in case a conversion to ankle replacement is warranted in the future. Regarding arthroscopic ankle arthrodesis, one study reported on 101 ankles in 97 patients who underwent this procedure on average 86 months prior.¹¹ The authors demonstrated that 95% of the ankles achieved fusion with the primary procedure. There are no data to support one approach over another and therefore, the approach should be at the discretion of the surgeon based on previous incisions/wounds and any hardware removal needed.

Hardware fixation has been the topic of many reports. A comparison study of compression screws alone versus compression screws supplemented with anterior plate fixation demonstrated the nonunion rate in the compression screw only cohort was 15.4% versus only 7.7% when anterior plate augmentation was used¹² (Figure 1). These rates were not significantly different, likely based on the numbers in each cohort. Therefore, similar to the approach, there is no conclusive evidence to recommend one hardware construct over another. The authors typically perform ankle arthrodesis through an anterior approach and fixation is achieved via crossed screws and an anterior plate.

Mid- and long-term outcomes of ankle arthrodesis are favorable. One study reported on 72 ankle arthrodeses at a mean follow-up of 4.8 years and found a 99% fusion rate.¹³ Another study reported on 60 patients (66 ankles) with a mean follow-up of 9 years.¹⁴ There was a 91% primary arthrodesis rate. The remaining six patients achieved fusion after a second arthrodesis procedure.

One of the major problems with arthrodesis is the potential for nonunion. Chalayon et al¹⁵ identified risk factors affecting union and found that nonunion was significantly more likely to occur with previous ipsilateral subtalar fusion and preoperative varus alignment. Progression of adjacent joint (subtalar and/or talonavicular) disease following ankle arthrodesis is one reason ankle arthroplasty may be more favorable. In one study of 66 ankle fusions, the authors reported
significant radiologic progression of arthritis in all adjacent joints.¹⁴ Additionally, Coester et al¹⁶ reported adjacent joint arthritis in 23 patients with a mean follow-up of 22 years. They found that 91% and 57% of subtalar and talonavicular joints, respectively, developed moderate to severe arthritis. However, the clinical significance of adjacent joint disease progression is unknown.

Figure 1 AP (A) and lateral (B) radiographs of an ankle arthrodesis performed with a compression screw and anterior plate fixation.

Total Ankle Arthroplasty

Total ankle arthroplasty (TAA) is increasing in popularity as the preferred treatment for end-stage ankle arthritis, because it has demonstrated significant improvement in pain, function, radiographic parameters, and patient-reported outcomes.¹⁷ Although randomized trials of ankle arthroplasty to ankle arthrodesis are minimal, there are some data to support TAA over arthrodesis. A recent database study reported a significantly lower readmission rate and wound complication rate for TAA.¹⁸ Moreover, one nonrandomized, but prospective study reported equivalent patient-reported outcomes between ankle arthrodesis and ankle replacement, but a higher complication rate with ankle replacement.¹⁹

Modern TAA implant designs have demonstrated successful outcomes in the literature. Adams et al¹⁷ reported on 194 fixed-bearing, intramedullary prostheses at a mean of 3.7 years of follow-up. They demonstrated significant improvement in pain, function, radiographic parameters, and patient-reported outcomes and an 11% revision rate. A longer term study of the same prosthesis at minimum of 4- to 10-year follow-up demonstrated a 91% survival rate.²⁰

Although studies with early follow-up demonstrate remarkable results, longer term follow-up studies are less promising. A study of 111 mobile-bearing prostheses at a mean of 9 years of follow-up reported improved patient outcomes but a 12% revision rate for metal components.²¹ In an even longer term follow-up study on the same mobile-bearing prosthesis, Brunner and colleagues reported a 71% implant survival rate at 10 years and only a 46% survival rate at 14 years. In a series of 722 replacements, the authors demonstrated a 94% survival rate at 5 years and an 84% survival rate at 10 years and identified the cause of arthritis and age as independent risk factors for failure.²² One of the longest-term follow-up studies is of the Scandinavian Total Ankle Replacement (STAR, Stryker, Mahwah, NJ) reported on 34 replacements at a median of 13.3 years. The survivorship of the implant decreased with time. It was 94% at 5 years, 87% at 10 years, and 63% at 15 years.²³ Although TAA has demonstrated promising early clinical success, long-term follow-up is not as good.

TAA failure can be managed through arthrodesis, revision arthroplasty, or amputation (mainly for infection or major wound healing issues), but studies have demonstrated more beneficial results of revision TAA.²⁴^,²⁵ Revision TAA is defined as removal or exchange of one or more of the prosthetic components with the exception of incidental exchange of the polyethylene insert. A report of 41 revision TAAs at a mean follow-up of 49.1 months demonstrated satisfactory postoperative patient-reported outcomes.²⁴ There was a 13% revision TAA failure rate including subsequent arthrodesis or amputation procedures. Interestingly, they reported increased ankle ROM after revision TAA with all of the improvement occurring in plantar flexion. Another study of 117 revision TAAs showed a significant improvement in the American Orthopaedic Foot and Ankle Society (AOFAS) hindfoot score after at a mean of 6.2 years after revision.²⁵ They also reported that 15% of their cases needed a further revision surgery.

Hindfoot

Arthritis of the hindfoot includes the subtalar and talonavicular joints. Nonsurgical management includes anti-inflammatories, steroid injections, and bracing treatment. However, typically, these treatment modalities are short-lived because of patient compliance and medication tolerance. Because of the weight-bearing nature and stresses applied to the foot, arthritis is progressive and typically requires arthrodesis. Unlike the ankle and first metatarsophalangeal joints, arthrodesis is the only reliable surgical option for these two joints and will be discussed in the next paragraphs.

Figure 2 Nonunion of a subtalar fusion after prior successful ankle fusion is demonstrated by plain radiographs (A) and confirmed with CT scan (B).

Subtalar Joint

Subtalar arthrodesis can be performed through open or arthroscopically assisted approaches with generally favorable results.²⁶ One study retrospectively compared 60 open and 69 arthroscopically assisted subtalar arthrodeses.²⁷ The approach was not randomized, but both groups demonstrated significant improvement in activity level, pain, and patient-reported outcomes. There were no differences in these outcomes nor the union rate. However, the open group had a higher incidence of sural nerve injury and painful scar and the arthroscopically assisted group had more hardware-related symptoms. One of the major problems with subtalar joint arthrodesis is the relatively high nonunion rate. Ziegler et al²⁸ reported an almost 24% nonunion rate in 214 patients. When this population was broken down based on risk factors, the nonunion rate decreased to 12% in patients without any risk factors. The main risk factors for nonunion were obesity, smoking, and prior infection. Another risk factor that can contribute to subtalar arthrodesis nonunion is prior ipsilateral ankle arthrodesis. In fact, there is a significantly higher nonunion rate (38%) in patients with prior ipsilateral ankle arthrodesis²⁹ (Figure 2).

Subtalar arthrodesis in the setting of a prior calcaneus fracture requires special attention as these patients typically have loss of heel height and a relatively horizontal talus. The horizontal talus limits ankle dorsiflexion. In this setting, subtalar bone block arthrodesis has been reported to improve functional outcomes and
radiographic alignment.³⁰ The bone block wedge helps to restore the native talus alignment. A recent study demonstrated that although patient-reported outcome scores were low compared with a reference population, 90% of patients undergoing subtalar arthrodesis after calcaneus fracture would recommend the procedure to others and 76% of patients experienced pain relief.³¹

Talonavicular Joint

Isolated talonavicular arthritis typically occurs in the setting of rheumatoid arthritis or Mueller-Weiss disease. Favorable fusion rates of near 95% and improvement in patient-reported outcomes scores have been reported with this procedure.³²^,³³ However, hardware fixation in this relatively small joint is a concern. Plate and screws versus screws alone for the fixation of the talonavicular joint provided equivalent stability in a cadaver model.³⁴ However, another study reported that one retrograde screw and a dorsal locked compression plate was more effective at limiting motion across the talonavicular joint than two retrograde screws.³⁵

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