Background

Anatomical reduction of unstable Lisfranc injuries is crucial. Evidence as to the best methods of surgical stabilization remains sparse, with small patient numbers a particular issue. Dorsal bridge plating offers rigid stability and joint preservation.

The primary aim of this study was to assess the medium-term functional outcomes for patients treated with this technique at our centre. Additionally, we review for risk factors that influence outcomes.

When inserting a lag-screw across an arthrodesis, stress is concentrated under the screw head risking asymmetrical force distribution and fracture of the cortical bone bridge. The IO FiX (Extremity Medical, NJ USA) is a new intraosseous device comprising an X-Post on one side of and parallel to the arthrodesis and a lag-screw inserted through the head of the X-Post which reinforces the cortical bone bridge. The X-Post behaves as an internal washer improving force distribution across the arthrodesis. Being intraosseous, near to the neutral axis of bend also means the device is fatigue-resistant and soft tissue irritation is reduced.

The IO FiX has not been independently verified and therefore we analysed its performance in a human cadaveric ankle model. Our null hypothesis was there is no difference in force generation and contact area in an ankle arthrodesis when the IO FiX is compared with partially-threaded lag-screws.

We used ten randomized cadaver ankles with a mean age of seventy-one years (44–84 years) prepared with flat arthrodesis cuts. A Tek-scan (Boston, USA) pressure transducer was used to measure force and contact area produced when the IO FiX was compared with a standard lag-screw and washer.

The median average force in the IO FiX group was 3.95 kg and 2.35 kg in the lag-screw group (p=<0.01 Wilcoxon signed-rank). The IO FiX was able to create a more uniform contact area within the arthrodesis with a median average of 3.41 cm² compared with 2.42 cm² in the lag-screw group (p=<0.03 Wilcoxon signed rank).

Our results suggest the IO FiX improves force generation and contact area across the arthrodesis. With the theoretical advantages of reduced soft tissue irritation and a lower risk of fatigue failure, the IO FiX offers a significant advantage compared with traditional fixation techniques.

The AO Foundation advocates the use of partially threaded lag screws in the fixation of fractures of the medial malleolus. However, their threads often bypass the radiodense physeal scar of the distal tibia, possibly failing to obtain more secure purchase and better compression of the fracture.

We therefore hypothesised that the partially threaded screws commonly used to fix a medial malleolar fracture often provide suboptimal compression as a result of bypassing the physeal scar, and proposed that better compression of the fracture may be achieved with shorter partially threaded screws or fully threaded screws whose threads engage the physeal scar.

We analysed compression at the fracture site in human cadaver medial malleoli treated with either 30 mm or 45 mm long partially threaded screws or 45 mm fully threaded screws. The median compression at the fracture site achieved with 30 mm partially threaded screws (0.95 kg/cm² (interquartile range (IQR) 0.8 to 1.2) and 45 mm fully threaded screws (1.0 kg/cm² (IQR 0.7 to 2.8)) was significantly higher than that achieved with 45 mm partially threaded screws (0.6 kg/cm² (IQR 0.2 to 0.9)) (p = 0.04 and p < 0.001, respectively). The fully threaded screws and the 30mm partially threaded screws were seen to engage the physeal scar under an image intensifier in each case.

The results support the use of 30 mm partially threaded or 45 mm fully threaded screws that engage the physeal scar rather than longer partially threaded screws that do not. A 45 mm fully threaded screw may in practice offer additional benefit over 30 mm partially threaded screws in increasing the thread count in the denser paraphyseal region.

Cite this article: Bone Joint J 2013;95-B:1662–6.

Aims

The purpose of our study was three fold; firstly to assess the survival of closing wedge high tibial osteotomies (CWHTO), secondly to assess any clinical factors or radiological alignment which may affect survival and thirdly to assess the change in tibial inclination and patella height.

We report the results of a retrospective review of patients that underwent distal tibial deformity correction with transphyseal or supramalleolar osteotomy with or without tibial lengthening. The aims of the procedures performed were to obtain equal leg length, restore the alignment of the ankle joint and tibio—fibular relationship. Supramalleolar osteotomy enables deformity correction, can be combined with lengthening and is appropriate where the tibio—fibular relationship is normal. When the tibio—fibular relationship is abnormal, as is often the case with bone dysplasias, differential tibio—fibular lengthening can be performed. If physeal arrest has occurred, for example after sepsis, deformity correction can be achieved with a transphyseal osteotomy allowing correction and ensuring epiphysiodesis. When the fibular length is excessive, transphyseal osteotomy can be combined with a fibular shortening. Our review encompassed 12 patients over a period of 10 years with 5 having deformity after previous meningococcal septicaemia, 4 with fibular hemimelia, 2 with a history of previous trauma and 1 with deformity occurring after a compartment syndrome as a consequence of snake bite. Seven transphyseal osteotomies were performed in 5 patients (2 bilateral), 4 with deformity secondary to meningococcal septicaemia and 1 with deformity secondary to previous trauma. After 1 transphyseal osteotomy there was recurrent distal tibial deformity (14%) which occurred within 1 year requiring a later supramalleolar dome osteotomy. Of the other 6 transphyseal osteotomies all healed with no residual leg—length inequality or deformity. Seven patients underwent supramalleolar osteotomies with all healing and recurrent deformity occurring in 1 patient (14%). Future lengthening is required in 2 patients and 1 patient will undergo a subtalar joint arthrodesis for a painful valgus hindfoot. Distal tibial deformity correction is challenging but our results show that providing the stated principles are adhered to, successful management with an acceptable recurrent deformity rate is possible.

Conventionally, medial malleolus fractures are treated surgically with anatomical reduction and internal fixation using screws. There seems to be no consensus, backed by scientific study on the optimal screw characteristics in the literature.

We retrospectively examined case notes and radiographs of 48 consecutive patients taken from our trauma database (21 male, 27 female) with an average age of 50 years (range 16-85) who had undergone medial malleolus fracture fixation with screws at the Royal Free Hospital, London between January 2009 and June 2010.

The most commonly used screw was the AO 4.0 mm diameter cancellous partially-threaded screw in 40, 45 and 50 mm lengths (40 mm n = 28, 45 mm n = 26, 50 mm n = 23) with the threads passing beyond the physeal scar in all cases. Incomplete reduction defined as > 1mm fracture displacement was observed on post-operative x-rays in 12 out of 48 cases (25%), all of which relied on partially-threaded screw fixation. In 5 cases where AO 4.0 mm diameter fully-threaded screws engaging the physeal scar had been used, no loss of reduction was observed.

This unusual, occasional use of fully-threaded screws prompted us to investigate further using a porcine model and adapted pedo-barographic transducer. We compared pressures generated within the fracture site using AO 4.0 mm partially-threaded cannulated screws, 4.0 mm partially-threaded cancellous screws and 4.0 mm fully-threaded cancellous screws.

Fully-threaded cancellous 4.0 mm diameter screws generated almost 3 times the compression of a partially-threaded cancellous screw with superior stability at the fracture. Partially-threaded screws quickly lost purchase, compression and stability particularly when they were cannulated. We also observed that screw thread purchase seemed enhanced in the physeal region.

We conclude that fully-threaded cancellous 4.0 mm AO screws are superior to longer partially-threaded screws and that use of cannulated 4.0 mm partially-threaded screws should be avoided in fixation of medial malleolus fractures.

Morbid obesity and its association with obstructive sleep apnoea syndrome have been increasingly recognised in children. Orthopaedic surgeons are often the primary medical contact for older children with tibia vara, which has long been associated with obesity, but are unfamiliar with the evaluation and treatment of sleep apnoea in children.

We reviewed all children with tibia vara treated surgically at one of our institutions over a period of five years. Thirty-seven patients were identified; 18 were nine years of age or older and 13 of these (72%) had morbid obesity and a history of snoring.

Eleven children were diagnosed as having sleep apnoea on polysomnography. The incidence of this syndrome in the 18 children aged nine years or older with tibia vara, was 61%. All these patients required pre-operative non-invasive positive-pressure ventilation; tonsillectomy and adenoidectomy were necessary in five (45%). No peri-operative complications related to the airway occurred.

There is a high incidence of sleep apnoea in morbidly obese patients with tibia vara. These patients should be screened for snoring and, if present, should be further evaluated for sleep apnoea before corrective surgery is undertaken.