Aims

Patients undergoing femoral lengthening by external fixation tolerate treatment less well when compared to tibial lengthening. Lengthening of the femur with an intramedullary device may have advantages.

Internal lengthening devices in the femur lengthen along the anatomical axis, potentially creating lateral shift of the mechanical axis. We aimed to determine whether femoral lengthening along the anatomical axis has an inadvertent effect on lower limb alignment. Isolated femoral lengthening using the Intramedullary Skeletal Kinetic Distractor was performed in 27 femora in 24 patients (mean age 32 years (16 to 57)). Patients who underwent simultaneous realignment procedures or concurrent tibial lengthening, or who developed mal- or nonunion, were excluded. Pre-operative and six-month post-operative radiographs were used to measure lower limb alignment. The mean lengthening achieved was 4.4 cm (1.5 to 8.0). In 26 of 27 limbs, the mechanical axis shifted laterally by a mean of 1.0 mm/cm of lengthening (0 to 3.5). In one femur that was initially in varus, a 3 mm medial shift occurred during a lengthening of 2.2 cm.

In a normally aligned limb, intramedullary lengthening along the anatomical axis of the femur results in a lateral shift of the mechanical axis by approximately 1 mm for each 1 cm of lengthening.

We compared lower limb coronal alignment measurements obtained pre- and post-operatively with long-leg radiographs and computer navigation in patients undergoing primary total knee replacement (TKR). A series of 185 patients had their pre- and post-implant radiological and computer-navigation system measurements of coronal alignment compared using the Bland-Altman method. The study included 81 men and 104 women with a mean age of 68.5 years (32 to 87) and a mean body mass index of 31.7 kg/m² (19 to 49). Pre-implant Bland–Altman limits of agreement were -9.4° to 8.6° with a repeatability coefficient of 9.0°. The Bland–Altman plot showed a tendency for the radiological measurement to indicate a higher level of pre-operative deformity than the corresponding navigation measurement. Post-implant limits of agreement were -5.0° to 5.4° with a repeatability coefficient of 5.2°. The tendency for valgus knees to have greater deformity on the radiograph was still seen, but was weaker for varus knees.

The alignment seen or measured intra-operatively during TKR is not necessarily the same as the deformity seen on a standing long-leg radiograph either pre- or post-operatively. Further investigation into the effect of weight-bearing and surgical exposure of the joint on the mechanical femorotibial angle is required to enable the most appropriate intra-operative alignment to be selected.

The use of autograft bone is the best option when undertaking a procedure that requires bone graft because it is osteogenic, osteoconductive and osseo-inductive. Pain, morbidity and complications associated with harvesting iliac or non-iliac sites occur in between 6% and 30% of cases. An alternative source of graft with possibly a lower morbidity is the intramedullary canal. In this study, 28 patients undergoing 30 arthrodesis procedures on the hindfoot had a mean of 48 cm³ (43 to 50) of bone harvested locally from the hindfoot or the tibial shaft by antegrade or retrograde reaming. No patient sustained a fracture of the calcaneum, talus or tibia. There was no morbidity except for one complication when the reamer breached the medial tibial cortex. This healed uneventfully.

This method of using the reamer–irrigator–aspirator system is an extension of the standard technique of intramedullary reaming of the lower limb: it produces good-quality bone graft with viable growth factors consistent with that of the iliac crest, and donor site morbidity is low. This is an efficient method of obtaining autologous bone for use in arthrodesis of the ankle or hindfoot.

The treatment of osteochondral lesions of the talus has evolved with the development of improved imaging and arthroscopic techniques. However, the outcome of treatment for large cystic type-V lesions is poor, using conventional grafting, debridement or microfracture techniques.

This retrospective study examined the outcomes of 50 patients with a cystic talar defect who were treated with arthroscopically harvested, cored osteochondral graft taken from the ipsilateral knee.

Of the 50 patients, 45 (90%) had a mean good to excellent score of 80.3 (52 to 90) in the Karlsson-Peterson Ankle Score, at a mean follow-up of 36 months (24 to 83). A malleolar osteotomy for exposure was needed in 26 patients and there were no malleolar mal- or nonunions. One patient had symptoms at the donor site three months after surgery; these resolved after arthroscopic release of scar tissue.

This technique is demanding with or without a malleolar osteotomy, but if properly performed has a high likelihood of success.

We have assessed the proximal capsular extension of the ankle joint in 18 patients who had a contrast-enhanced MRI ankle arthrogram in order to delineate the capsular attachments.

We noted consistent proximal capsular extensions anterior to the distal tibia and in the tibiofibular recess. The mean capsular extension anterior to the distal tibia was 9.6 mm (4.9 to 27.0) proximal to the anteroinferior tibial margin and 3.8 mm (−2.1 to 9.3) proximal to the dome of the tibial plafond. In the tibiofibular recess, the mean capsular extension was 19.2 mm (12.7 to 38.0) proximal to the anteroinferior tibial margin and 13.4 mm (5.8 to 20.5) proximal to the dome of the tibial plafond.

These areas of proximal capsular extensions run the risk of being traversed during the insertion of finewires for the treatment of fractures of the distal tibia. Surgeons using these techniques should be aware of this anatomy in order to minimise the risk of septic arthritis.