Foot & Ankle

The lateral column of the foot is made up of the fourth and fifth metatarsals, the cuboid, the calcaneus and the intervening joints. The mobility of the lateral column is fundamental to the efficient functioning of the foot, as it is considered to play a central role in shock absorption, mobile adaptation, and as a rigid lever for the push-off phase in the gait cycle.

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Biomechanics

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During the stance phase of gait the heel strikes the floor in slight inversion, resulting in the fifth metatarsal to contact the supporting surface shortly after the heel, becoming fully loaded during the middle third of this phase and peaking at about two-thirds of the way through. The cuboid is temporarily suspended just before the central midstance phase when it contacts the ground to help transmit the body weight forward along the lateral column.

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Ouzounian and Shereff found the fourth and fifth metatarso-cuboid joints to have arcs of motion of approximately 10 degrees in both plantarflexion-dorsiflexion and supination-pronation. This was consistent with the findings of Hicks and Gellman. They also noticed that the range of motion of the calcaneo-cuboid joint was only 2 degrees for dorsiflexion-plantarflexion and about 7 degrees for supination-pronation.

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The causes of arthritis in 4th and 5th TMT joints include traumatic arthritis, degenerative disease, functional breakdown and Charcot neuroarthropathy.

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Patients present with pain along the lateral border of the foot, difficulty in weightbearing and shoewear and may have an abnormal gait pattern.

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Treatment

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Conservative Treatment

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Conservative management is always the first line and the mainstay of management in these patients. These modalities include NSAIDs, orthotics, insoles and modified shoewear.

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Injections are also used to localise the primary source of pain and for providing therapeutic benefit, however there are no studies available to comment on the effectiveness of injection therapy.

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Surgical Treatment

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Arthritis of 4th and 5th TMT joints is a challenging problem to manage. Even in cases of failed conservative treatment and persistent symptoms, very few surgeons would consider surgical intervention. In the literature, a few sporadic case reports and only one study is available to review the arthrodesis of these two joints.

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Arthrodesis

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Raikin and Schon (2003) retrospectively reviewed the outcomes of 23 patients (28 feet) who had undergone midfoot arthrodeses, including the fourth and fifth TMT joints. Majority of the patients underwent surgery to correct neuroarthropathic deformities. Six arthrodeses were of the fourth and fifth TMT joints were performed for isolated degenerative disease in non-neuropathic feet. Two of these patients had post-traumatic arthritis, one had rheumatoid arthritis, two had non-traumatic degenerative arthritis and one had chronic cavus foot deformity. The average pain scores (AOFAS midfoot scale) for this small arthritic group improved significantly (from 8.2 preoperatively to 2.4 postoperatively), indicating a 70% decrease in lateral column pain. The authors also reported a 73.8% improvement in dysfunction, after an average of 37 months of follow-up.

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Although this was a very small study with a handful of patients who underwent surgery, but the results provided some encouragement and showed that a permanent immobilisation of these two joints did not lead to lateral column overload or resulted in long-term pain, non-union, stress fractures and subsequent adjacent joint disease.

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Even after fusion of the 4th and 5th TMT joints, the calcaneo-cuboid joint can provide enough motion to keep the lateral column comfortably functional. However, when calcaneo-cuboid joint is also fused, then there is a definite overloading on the lateral column, which becomes a rigid lever.

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Another study by Raikin and Schon of arthrodesis of the 4th and 5th TMT joints reported an overall 74.5% improvement in pain and a 73.8% improvement in dysfunction, after an average of 37 months of follow-up.

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Interposition Arthroplasty

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Berlet et al. described a procedure involving resection of the dysfunctional 4th and 5th TMT joints and interposition of a tendon graft in the resulting space. The authors reported a 40% improvement in dysfunction and a 50% improvement in pain at an average of 24 months follow-up.

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Ceramic Implant Arthroplasty

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A case report has described the use of Zirconia Ceramic implant in 5th TMT joint. This was originally developed for arthritis of the carpo-metacarpal joints in the hand. This case report described on 6 months follow-up, at which the patient was able to walk 2-3 miles daily and was able to perform all of her normal daily activities without any pain or discomfort.

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