Changes in the subtalar joint alignment after supramalleolar osteotomy for varus ankle arthritis

BACKGROUND

The subtalar joint may compensate for tibio-talar deformity, but what would happen to the joint after the deformity was corrected is not well known. Supramalleolar osteotomy (SMOT) is an effective procedure for the treatment of varus deformity of ankle arthritis. The objective of this study was to investigate the subtalar joint alignment pre and postoperatively following SMOT, and the factors which influenced the alignment of the subtalar joint.

METHODS

Thirty-one patients with varus ankle arthritis (Takakura stage 2, 3a and 3b) who were treated using SMOT were retrospectively reviewed. The subtalar and ankle joint alignment was measured on weightbearing radiograph and weightbearing computerized tomography (WBCT).

RESULTS

The foot and ankle offset (FAO), tibial articular surface angle (TAS), tibio-talar surface angle (TTS), and subtalar vertical angle (SVA) were significantly corrected (P＜0.05). The subtalar inclination angle (SIA) decreased in 19 patients and increased in the other 12 cases after the SMOT (P＜0.001). The shift of subtalar joint (ΔSIA) showed an inverse correlation with the preoperative FAO (P＜0.001, r = -0.621).

CONCLUSIONS

The shift of subtalar joint after SMOT could maintain the neutral position of the hindfoot and showed a negative correlation with the preoperative FAO. The ΔSIA was greater in the severer preoperative hindfoot deformity.

LEVEL OF EVIDENCE

Level IV, case series.

Characteristics of medial gutter arthritis on weightbearing CT and plain radiograph

OBJECTIVE

An ankle arthritis with medial gutter obliteration is known to have good results after joint preservation surgery. However, the diagnosis is often missed on radiographs. The aims of this study were to investigate sensitivity of radiographs in the identification of medial gutter arthritis, incidence and direction of the talar tilt on weightbearing CT (WBCT), and to assess radiographic alignment of the medial gutter arthritis.

MATERIALS AND METHODS

Radiographic data was retrospectively evaluated in 102 ankles which were diagnosed medial gutter arthritis by using the WBCT at our clinic between January 2017 and June 2019. Among the 102 ankles, proportion of ankles which showed medial gutter arthritis on plain radiograph was obtained. The presence and direction of talar tilt were assessed on three coronal WBCT images at the anterior, middle, and posterior aspect of the ankle. Plain radiographic parameters were compared between the 102 ankles and control group.

RESULTS

Plain radiograph showed medial gutter arthritis only in 63 ankles (62%) among the 102 ankles. Most of the ankles with medial gutter arthritis showed talar tilt on WBCT, and about half of all ankles showed valgus talar tilt at the anterior aspect of ankle on WBCT. In ankles with medial gutter arthritis, the mechanical axis of the lower extremity and the tibial plafond were varus angulated and the talus was medially translated compared to the control group.

CONCLUSION

Radiographs were less sensitive than WBCT in demonstrating medial gutter arthritis. Anterior aspect of ankles with medial gutter arthritis often showed valgus direction of talar tilt. Varus mechanical axis deviation and varus tibial plafond are commonly associated with the medial gutter arthritis.

The role of fibular for supramalleolar osteotomy in treatment of varus ankle arthritis: a biomechanical and clinical study

Background

Supramalleolar osteotomy (SMOT) is a well-accepted treatment method for mid-stage varus ankle osteoarthritis (OA). However, few studies have examined the role of fibular osteotomy in SMOT. The objective of the current study was to compare the biomechanical and clinical outcomes of SMOT with and without fibular osteotomy.

Methods

Eight cadaveric lower legs with 10° varus/valgus SMOT models were tested using a Tekscan ankle sensor. Tibiotalar joint contact with and without fibular osteotomy conditions were compared. Forty-one varus ankle OA patients treated with SMOT were included; 22 underwent fibular osteotomy, and 19 did not. The Maryland foot score and radiological angles were used for clinical evaluation.

Results

The mean contact area and pressure did not differ significantly between normal and varus/valgus conditions with the fibula preserved. After fibular osteotomy, the mean contact area decreased and the mean contact pressure increased significantly in varus and valgus conditions (P < 0.01). The loading center moved to the opposite direction with and without fibular osteotomy in varus/valgus conditions. After a mean follow-up of 36.6 months (range 17–61), there was no significant difference in the Maryland scores of the two groups. However, in the fibular osteotomy group, the talar tilt angle decreased (P < 0.05), and the tibiocrural angle improved significantly (P < 0.01).

Conclusions

Fibular osteotomy facilitates the translation of tibiotalar contact pressure and is helpful for varus ankle realignment in patients with large talar tilts and small tibiocrural angles.

Management of varus ankle osteoarthritis with joint-preserving osteotomy

The goal of osteotomy in the treatment of varus ankle arthritis is to shift the forces imparted to the ankle to a portion of the joint that is not involved in the degenerative process. The redistribution of loads and stresses seen by the tibiotalar joint can be approached either above or below the ankle with an osteotomy of the tibia or calcaneus. Evaluation of the deformity as being subtalar, supramalleolar, or a combination allows the surgeon to best address the increased joint stresses, thereby reducing the risk of failure of the osteotomy.