In recent years numerous advances have been made in reconstructive surgery for disorders of the foot and ankle. The research endeavors of the Harvard Foot and Ankle Service aim both to more clearly understand these disorders and as well to develop and evaluate new treatment strategies.

Posterior Tibial Tendon Dysfunction

          The posterior tibial tendon is an important dynamic stabilizer of the hindfoot.1, 2 Running directly behind the medial malleolus, it inserts on the navicular as well as the three cuneiforms and the bases of the second through fourth metatarsals. As such, it plantarflexes and inverts the foot while also elevating the medial longitudinal arch and locking the transverse tarsal joint.3, 4

           The term "posterior tibial tendon dysfunction" encompasses a pathologic and clinical spectrum that ranges from isolated synovitis to complete tendon rupture with associated deformity. With tendon rupture, patients develop an acquired flatfoot deformity, otherwise known as pes planovalgus. This deformity is characterized by hindfoot valgus and forefoot abduction. Although not entirely understood, this is believed to result from the unopposed pull of the peroneal musculature laterally and the subsequent attenuation of those ligaments and other soft tissues medially which stabilize the longitudinal arch of the foot.5, 6

          Patients with posterior tibial tendon dysfunction experience both pain and disability. The pain begins along the medial aspect of the foot and is commonly associated with swelling if a significant degree of tenosynovitis is present. With collapse of the longitudinal arch and the subsequent development of a hindfoot valgus deformity, lateral foot pain develops as the fibula impinges on the calcaneus. Patients also notice earlier fatigue and a decrease in their walking endurance.7 They find standing on their toes difficult and painful, and report abnormal shoe wear. Athletic activities become difficult if not impossible.7, 8

          Posterior tibial tendon dysfunction has been classified into three stages.9 Stage I is characterized by isolated synovitis. The tendon is still functional and the hindfoot is normally aligned. Stage II is defined by tendon rupture with an associated planovalgus deformity but a supple hindfoot. Patients are unable to do a single-leg heel rise on the involved extremity. With Stage III disease, the deformity is more severe and the hindfoot is rigid.

           The treatment of patients with Stage I posterior tibial tendon dysfunction is primarily supportive, and includes anti-inflammatory medications and immobilization. In most cases these measures are successful. If symptoms do persist, however, operative tenosynovectomy and debridement is an effective alternative.10, 11 On the other end of the spectrum, patients with Stage III disease often have advanced degenerative changes of the joints of the hindfoot and usually require triple arthrodesis.

          The treatment of patients with Stage II disease remains controversial. Non-operative management can effectively reduce pain and prevent progression of deformity, especially in patients with advanced age, sedentary lifestyle, and significant medical comorbidities.12, 13 Nevertheless, most authors would agree that conservative management acts mainly as a temporizing measure prior to surgical intervention.3 Numerous operative procedures have been advocated. These include selective hindfoot arthrodesis14, triple arthrodesis15, 16, tendon transfer7, tendon transfer supplemented with a calcaneal osteotomy17, and lateral column lengthening procedures.18-20 To date, no single procedure has been universally successful at treating patients with Stage II disease.

          When the American Orthopaedic Foot and Ankle Society held their 14th Annual Summer Meeting in Boston last year, Dr. Michael Wilson co-moderated a symposium on posterior tibial tendon dysfunction which highlighted a number of the issues regarding Stage II disease. Data were presented on a potential auto-immune etiology21; on the role of the peroneal tendons in the development of hindfoot valgus after posterior tibial tendon rupture22; and on the results of a non-operative treatment protocol.23 Also presented was a biomechanical study which demonstrated the inadequacy of flexor digitorum longus transfer without hindfoot osteotomy to treat patients with Stage II disease.24

          Currently, the Harvard Foot and Ankle Service is collaborating with the Surgical Planning Laboratory at the Brigham and WomenÕs hospital to more precisely define the deformity produced by posterior tibial tendon dysfunction. In this protocol, weight-bearing CT scans of the feet, a technique developed by Drs. Wilson and Chiodo in conjunction with Dr. Daniel Williamson of the Brigham and WomenÕs Hospital, are being obtained in patients with Stage II disease. Three dimensional hindfoot reconstructions are then created and analyzed using software that determines and quantifies the exact positional changes of the bones of the hindfoot as they rest under physiologic load.
Such detailed analyses of hindfoot anatomy under physiologic loads will certainly help quantify the results of treatment and may also help us to better understand the complex pathomechanics that produce the planovalgus deformity. These tools may also facilitate the development of new, computer-guided surgical osteotomies which will better alleviate the symptoms and dysfunction associated with pes planovalgus by more precisely restoring the normal anatomical relationships of the hindfoot.

Osteochondral Lesions of the Talus

           Osteochondral lesions of the talus are another challenging problem in foot and ankle surgery. They are often overlooked as a source of continued symptoms following ankle sprains. One study reported osteochondral lesions in 9 of 133 patients with ankle sprains.25 While the majority of osteochondral lesions are believed to be the result of either a discrete traumatic event or repetitive microtrauma, some are of uncertain origin. The concept of idiopathic osteonecrosis has been suggested26 and this diagnosis should be kept in mind when treating patients with unexplained ankle pain.

           A commonly used radiographic classification of osteochondral lesions described by Berndt and Harty identifies four radiographic stages: Stage I represents a small area of subchondral compression; Stage II, a partially detached fragment; Stage III, a completely detached but nondisplaced lesion; and Stage IV, a completely detached and displaced fragment.27 Nonoperative treatment is recommended for Stage I and II disease with immobilization and protected weight-bearing. Surgical treatment is felt to be indicated for all Stage III and IV lesions, and when conservative treatment of Stage I and II lesions fails to relieve symptoms.26

           Until recently, operative treatment of Stage III and IV lesions was limited to debridement of the lesion with either drilling or microfracture of the subchondral bone. This was intended to stimulate the migration of chondrogenic precursor cells that were capable of healing the defect. Unfortunately, these techniques have been shown to result in the generation of fibrocartilage, rather than hyaline cartilage.2, 28 Such fibrocartilage has been shown to be less durable than hyaline cartilage29 and the long-term clinical results of patients treated with subchondral perforation techniques have been suboptimal.30, 31 The results of newer surgical alternatives for the treatment of large osteochondral lesions have varied. At the 66th Annual Meeting of the American Academy of Orthopaedic Surgeons in Anaheim this year, Drs. Tammy Martin and Michael Wilson presented the short term results of a group of patients treated with debridement of the lesion and application of a solid, contoured plug of autogenous cancellous bone from either the tibia or the iliac crest.32 Clinically, nearly a quarter of patients were deemed failures, while little more than a third had a good or excellent short term result. Nevertheless, 75% of patients had complete or near-complete incorporation of the bone graft with restoration of the subchondral architecture.(Figure 1) The authors feel that open bone grafting may be an excellent strategy to restore subchondral bone as an initial step in a staged reconstruction with eventual cartilage transplant.

          Data on two alternative methods of operative treatment for osteochondral lesions were also presented at the AAOS meeting in Anaheim. Kumai and colleagues presented a series in which contained lesions were reduced and then internally fixed with autogenous cortical bone pegs.33 Twenty-seven patients were followed for an average of seven years, and good results were documented in 89% of cases.

           Meanwhile, Hangody and colleagues updated their series of patients undergoing transplantation of solid autogenous osteochondral plugs from a non-weightbearing region of the knee into an osteochondral defect in the talus - so-called mosaicplasty. In his original series published in 1997, Hangody reported on 11 patients with OCD lesions 10 mm or greater in diameter and evaluated at an average of 16 months post-operatively.34 All 11 patients had excellent results and returned to full activities. This year, Hangody reported on a total of 31 patients with similar lesions at an average of three and a minimum of two years follow-up.35 All patients again improved their ankle scores to good or excellent.

           Currently, the Foot and Ankle Service is investigating the promising technique of mosaicplasty in an ongoing prospective trial. Preliminary results should be available within the next year.

The Rheumatoid Foot and Ankle

           Elsewhere, the Foot and Ankle Service continues to evaluate its extensive experience with the surgical treatment of patients with rheumatoid arthritis. The results of isolated arthrodesis for inflammatory arthritis of the talonavicular joint were presented by Dr. Christopher Chiodo at the 65th Annual Meeting of the American Academy of Orthopaedic Surgeons last year in New Orleans. This study demonstrated the short-term success of isolated talonavicular arthrodesis in the treatment of symptomatic rheumatoid and inflammatory arthropathies of the talonavicular joint. The rate of solid fusion with good or excellent result was over 90%.36 Our technique involves the use of indirect joint distraction combined with simultaneous screw and staple fixation (Figure 2). Such operative tactics are important as it can be difficult to gain healing of an isolated talonavicular arthrodesis.

          Total ankle arthroplasty in patients with rheumatoid arthritis is another surgical procedure in Foot and Ankle surgery which continues to evolve. In the past, most intermediate and long-term results with this procedure, in both patients with rheumatoid arthritis and post-traumatic osteoarthritis, had been disappointing.37-40 With advances in prosthesis design and surgical technique, however, the results have been improving.41-43 Last year, Pyevich and co-workers at the University of Iowa published the results of 85 total ankle arthroplasties at an average of 4.8 years follow-up using a cementless implant in association with arthrodesis of the tibiotalar syndesmosis.42 The majority of their patients had post-traumatic osteoarthritis, with only 22% having rheumatoid arthritis. At an average of 4.8 years of follow-up, 83% of patients were either asymptomatic or minimally painful, and only five patients required revision surgery.

          These results are similar to those which Drs. Tom SanGiovanni and Michael Wilson will be presenting at this yearÕs annual summer meeting of the American Orthopaedic Foot and Ankle Society in San Juan. In the Brigham series of over 20 rheumatoid patients undergoing second-generation cementless total ankle arthroplasty for severe involvement of the tibiotalar joint (Figure 3), intermediate evaluation (average just over 5 years) revealed a high level of overall patient satisfaction (86%), and only three clinical failures. In our opinion, major improvements in prosthetic design such as cementless fixation and decreased constraint are making total ankle arthroplasty a more predictable procedure. Total ankle arthroplasty remains a viable alternative to tibiotalar arthrodesis, particularly for lower demand rheumatoid patients.

Christopher P. Chiodo, MD is a Resident in the Harvard Combined Orthopaedic Residency Program

Michael Wilson, MD is Chief of the Harvard Foot and Ankle Service, and Clinical Instructor of Orthopaedic Surgery at Harvard Medical School

Address correspondence to:
Michael Wilson, MD; Department of Orthopaedics;
Brigham and WomenÕs Hospital; 75 Francis St.; Boston, MA 02115