Leg Length Discrepancy in Unilateral Congenital Clubfoot Following Surgical Treatment

Abstract

Length discrepancy secondary to limb hypoplasia has been described as an associated finding in patients with unilateral clubfoot. In this manuscript we bring attention to limb length discrepancy as a result of surgical treatment in unilateral clubfoot. Three patients who underwent extensive posterior, medial and lateral release were noted to have an average discrepancy in foot height of 2.1 centimeters (range, 2.0-2.3 centimeters). A decrease in foot height in addition to baseline limb hypoplasia may lead to a significant discrepancy that may justify surgical treatment. In this manuscript we point out that length discrepancy in such cases may not be adequately quantified on standard anteroposterior scanograms. Standing lateral foot radiographs will document loss in foot height as a possible factor in length discrepancy in surgically treated clubfoot patients.

INTRODUCTION

The initial management of clubfoot has not changed a great deal since the time of Hippocrates (460-377 BC).¹⁰ It is generally accepted that preliminary management of clubfoot should be non-operative; in North America, the preferred approach utilizes variably described serial manipulations followed by short- or long-leg casting.^{3,4,6,18,20,21} Should the deformity prove resistant to non-operative treatment, operative intervention may be considered to correct residual deformity. Despite differences in surgical incision and approach, most authors recommend release or lengthening of ligaments and tendons, which variably constitute posterior, medial and/or lateral release.^{1,2,5,7,8,14,16,19,24}

Immediate complications of extensive surgical release include infection, skin slough and breakdown, or neurovascular compromise. Intermediate term complications include recurrence of deformity and need for adjunctive treatment. Longer-term outcomes may include over-correction, under-correction, stiffness and pain. An associated finding in unilateral congenital clubfoot includes limb length discrepancy,¹² which may be attributed to limb hypoplasia with tibial and/or femoral shortening.^9,15,26 Limb length discrepancy may also be secondary to a decrease in foot height, which rarely exceeds one centimeter.^11,15,26

It is the purpose of this series to bring attention to an excessive loss in foot height as a complication following surgical release in unilateral clubfoot. We report three patients who underwent extensive surgical release for the treatment of resistant idiopathic clubfoot and whose limb length deformity was inadequately quantified with standard scanograms.

CASE REPORTS

Case 1:

H.B. was born with unilateral clubfoot involving her left lower extremity. She was treated with manipulation and casting for the first four months of her life when the left foot continued to show marked heel varus, rigid metatarsus adductus and dorsiflexion to five degrees. Radiographs documented talocalcaneal angles of ten degrees on anteroposterior and five degrees on lateral radiographs. Casting with manipulation was discontinued and surgical correction was elected.

At 11 months of age, H.B. underwent surgical reconstruction, which has been previously described.⁷ Through a Turco-style medial skin incision, the Achilles tendon was z-lengthened and the fibro-fatty pulvinar between the Achilles and the tibiotalar and subtalar joints was resected. Complete subtalar release including the interosseus ligament was performed. Abductor hallucis muscle and plantar fascia were released. The posteromedial release was continued with z-lengthening of the posterior tibialis, flexor digitorum longus and flexor hallucis longus. The master knot of Henry was excised as well. Release of the talonavicular and calcaneocuboid joints and sectioning of the spring ligament were performed with the Navicular pinned in a reduced position. A pin was also passed through the talus and calcaneus following correction of hindfoot varus and equines. Anterior tibialis transfer to the midfoot was also performed prior to closure and placement in a long-leg cast for six weeks. After cast removal, straight last shoes and night splints were used for eight months post-operatively.

At two-and-a-half years of age, H.B. began to show evidence of over-correction into valgus with left calf atrophy. At four years of age, H.B. was ambulating well with a clinical leg-length discrepancy (left shorter) of one-and-one-half centimeters as measured from the anterior superior iliac spine to the medial malleolus. Her clinical discrepancy progressed and at 12 years of age she had a noticeable limp with asymmetric standing knee heights and a negative Galeazzi sign. In the prone position her left tibia and foot appeared to be four centimeters shorter than the right (Figure 1). Standard anteroposterior scanograms of the lower extremities at that time showed a discrepancy of 2.0 centimeters in the left tibia in comparison to the right (Figure 2). Due to the discordance between clinical and radiographic measurements, it was speculated that the additional loss of length was coming from the discrepancy in foot height. This was inadequately quantified on the scanograms and was confirmed on standing lateral foot films and a lateral leg-foot scanograms (Figure 3). The later radiographs identified a 2.0-centimeter loss in foot height in addition to the previously noted tibial discrepancy of 2.0 centimeters. In order to recoup the total discrepancy, distal femoral and proximal tibial epiphysiodesis were performed at 12 years, 3 months of age. She did well following the procedure and at one-year follow-up she has limb length discrepancy of 2.5 centimeters in the left leg and foot with one year of growth remaining.

Figure 1. Photo of HB in prone position at 12 years of age demonstrating a significant discrepancy with an overcorrected foot in comparison to the other.

Figure 2.

Anteroposterior scanograms of HB at 12 years of age demonstrating a 2.0-centimeter discrepancy in the left versus the right tibia.

Figure 3.

Left and right lateral leg and foot scanograms of HB at 12 years of age demonstrating a total discrepancy of 4 centimeters.

Case 2:

M.C. was born with unilateral clubfoot involving his left lower extremity. He was treated with serial manipulation and casting for the first three months of his life followed by corrective shoes. Initial evaluation at our hospital was at 17 months of age. Physical examination of the left foot at that time continued to show residual equines and varus, and surgical intervention was elected upon. Surgical correction consisted of posterior, medial and lateral release with dorsal transfer of tibialis anterior as described above. After surgery, a long-leg cast was placed and was continued for eight weeks post-operatively. Following cast removal, he wore night splints and straight last shoes.

At two years and nine months postoperative follow-up, M.C. showed left calf atrophy and slight heel valgus. Radiographs demonstrated that the talus was also medially and inferiorly subluxed. Physical examination at 11 years old showed the left foot was two sizes too small and a clinical limb length discrepancy of 2.5 centimeters (left lower extremity shorter than right). Anteroposterior scanograms at 13 years of age revealed a tibial discrepancy of 0.5 centimeters. A loss in foot height of 2.3 centimeters was noted when comparing standing lateral radiographs of the left foot to the right (Figures 4 and 5). Although he complains of occasional foot pain, a custom shoe insert accommodates his collapsed arch and limb-length discrepancy. The family is considering the option of contralateral epiphysiodesis at a later age in order to recoup his deficit.

Figures 4 and 5.

Left and right standing lateral foot radiographs of M.C. at 11 years of age demonstrating a 2.3-centimeter discrepancy in foot height.

Case 3:

J.G. was born with right unilateral clubfoot and was treated with serial manipulation and casting started at one day of age. At 11 months of age the right foot continued to show rigid metatarsus adductus, varus and equines deformity and surgical correction was elected.

J.G. underwent posterior, medial and lateral release as described above without dorsal transfer of the anterior tibialis tendon. He was placed in a long-leg cast for six weeks following the procedure, after which he wore night splints and straight last shoes for one year. At three years of age, J.G. was able to perform all activities despite calf atrophy that was noted on physical examination. At thirteen years, J.G. began to develop pain about the right foot and ankle. Physical examination revealed the right foot to be in excessive valgus with attendant weakness of the gastrocnemius-soleus muscles as well as hyperextension of the right hallux during swing phase. Standing lateral radiographs taken at that time revealed talar flattening and a decrease in foot height of 2.0 centimeters in comparison to the contralateral foot (Figures 6 and 7).

Figures 6 and 7.

Left and right standing lateral foot radiographs of J.G. at 13 years of age demonstrating a 2.9-centimeter discrepancy in foot height.

DISCUSSION

Wynne-Davis, in 1964, reported a study of 47 individuals with unilateral clubfoot, with less than half having a leg-length discrepancy. One-third had some loss in foot height, which was not quantified. One-half of the affected males had a leg-length discrepancy while all of the females had a leg-length discrepancy. This finding was attributed to the earlier closure of the epiphyses in females. Little et al. reported an incidence of limb length discrepancy in unilateral clubfoot of 18 percent with an average discrepancy of 2.1 centimeters.¹⁵ In this review, tibial shortening made up the majority of the loss in height. Yet due to the high incidence of femoral length discrepancy, they hypothesize that global limb hypoplasia is the cause of significant limb length discrepancy. Of the 259 patients with unilateral clubfoot, the authors do not objectively measure the amount of loss in foot height, but maintain an average loss of ten millimeters in nine percent of unilateral clubfeet. Unfortunately, the authors do not describe the treatments utilized in these patients, yet they suggest increased limb length discrepancy in patients with multiply operated feet.

Some mild decrease in foot height should be expected in unilateral clubfoot, yet we are unaware of any cases of significant discrepancy as a result of loss in foot height in patients who are treated with manipulation and casting alone. Untoward outcomes of surgical correction of clubfeet include: Wound infection, skin necrosis, severe scarring, stiff joints, ankle and subtalar joint pain, over-correction and heel valgus, under-correction, dislocation of the Navicular, fracture and flattening of the talus or necrosis, weakness of the plantar flexors and calf atrophy, and decrease in foot size.^{2,9,14,17,19,22,25,26} Significant discrepancy as a result of loss in foot height is heretofore an apparent result of extensive surgical release. Huang et al. also found that loss in foot height is a potential complication in the treatment of clubfoot.¹¹

Mild decrease (<one centimeter) in foot height in clubfeet may be due to hypoplasia of the calcaneus and talus.^13,26 In our series, the loss in height on standing lateral radiographs is approximately 2 to 2.3 centimeters. The discrepancy is apparently due to a combination of midfoot collapse, excessive hindfoot valgus and possible growth retardation of the talus and os calcis. Others have also speculated that apparent calcaneal shortening in radiographs of children with clubfoot may be due to true shortening of the calcaneus or secondary to rotation of the calcaneus in the coronal plane.²³ We theorize that extensive surgical release may predispose to late collapse at Chopart's joints as well as a tendency to drift into extreme valgus. Although it is difficult to prove, it also seems reasonable that wide peri-talar release may predispose to growth retardation of the talus as a result of vascular insult at the time of release.

An important point in this report is the observation that clinical limb-length discrepancy may not be adequately quantified on standard anteroposterior studies such as a scanograms. In patients with unilateral clubfoot it is critical to realize that fairly significant discrepancy may be due to a loss in foot height after extensive surgical release. The total discrepancy may become significant in prepubescent patients with a combination of limb hypoplasia and postoperative loss in foot height (Case 1). Measuring the difference in distance from the talar dome to the floor on standing lateral foot films easily assesses the discrepancy and may be added to any concurrent shortening of the leg.