The use of a nerve stimulator to allow safe placement of Ilizarov wires.

OBJECTIVE: Avoidance of potential iatrogenic nerve injury during insertion of Ilizarov fine wires into areas of high anatomic risk by using a modified nerve stimulation technique. INDICATIONS: Application of the Ilizarov ring fixator to areas of high anatomic hazard, in situations where anatomic topography may be distorted by previous surgery, trauma, or congenital anomalies. CONTRAINDICATIONS: Use of systemic muscle relaxants. Caution in patient with cardiac pacemaker. SURGICAL TECHNIQUE: Preliminary experiments showed that a standard nerve-stimulating device can deliver a negatively charged, monophasic square pulse of current through Ilizarov wires. During the application of an Ilizarov frame to potentially hazardous anatomic regions, providing no systemic muscle relaxants are used, a voltage field sufficient to cause nerves in close proximity to the Ilizarov wire to depolarize is produced. Identification of a distal muscle twitch provoked by the stimulation may indicate a potential for iatrogenic nerve injury. RESULTS: Results show that with the nerve stimulator set at 2.5 mA (pulsed at a frequency of 2 Hz), peripheral nerves are stimulated if they lie within 5 mm of the wires. Should a distal muscle twitch occur, wires should be repositioned so that equivalent stimulation produces no twitch. The technique was used during Ilizarov frame application in ten patients, with only a single occurrence of distal muscle twitches in a lower-leg frame. Following repositioning of the Ilizarov wire in this case, no further twitches were observed, indicating that no Ilizarov wire was inserted close to peripheral nerves. No neurologic impairment was present postoperatively.

Predicting the loss of knee flexion during limb lengthening using inherent muscle length.

Limb lengthening procedures can be associated with loss of range of knee movement, although the amount of knee flexion lost varies markedly between patients. The exact aetiology of this problem is not fully understood. This study investigates whether the amount of joint range that is lost during limb lengthening might be affected by the inherent passive compliance and length of the patients' soft tissues determined preoperatively. A simple mathematical model has been developed to calculate the inherent length and 'spare' length of the hamstring and quadriceps muscle groups in 28 patients undergoing limb lengthening procedures. The range of knee motion was recorded preoperatively and loss of movement recorded during follow-up. The results show a strong correlation between predicted 'spare' length of quadriceps and loss of knee flexion. An association was noted between loss of knee extension and the straight leg raise and correlation of knee extension and the spare length of the hamstrings. The straight leg raise test, and calculation of spare quadriceps length using our formula, as part of the preoperative assessment, can help predict which patient is at risk of a reduced range of motion of the knee.

Mortality after low-energy fractures in patients aged at least 45 years old.

BACKGROUND: Fractures sustained in low-energy injuries are recognized as a major public health issue, although, with the exception of proximal femoral fractures, little is known about the subsequent mortality rates. The aim of this study was to compare the survival rates of a population of individuals who sustained 3 types of low-energy fractures with age-matched cohorts from within the same population. METHODS: Between January 1988 and December 1999, data were prospectively gathered from all inpatient and outpatient fracture cases at a single trauma unit. During this time, 18,019 patients sustained low-energy fractures of the proximal femur, proximal humerus, or wrist. Survival analysis using the life table method was performed and hazard ratios calculated for risk of mortality when compared to general population controls within the first year postinjury, between the second and fifth years postinjury, and between the sixth and tenth years postinjury. The effects of various social, physical, and mental health parameters on survival were also analyzed using a Cox proportional hazards model. RESULTS: The patients who sustained proximal femoral fractures were older and significantly more physically and mentally impaired than the patients who sustained wrist fractures. The demographic features of the proximal humeral fracture cohort were intermediate between these 2 groups. The mortality was high in all age groups following proximal femoral and proximal humeral fractures, though the relative risk of death, when compared to age-matched population controls, decreased with increasing age at fracture. The risk of death in these groups was greatest in younger individuals and in the first year postinjury. The wrist fracture population had similar or enhanced survival when compared to age-matched population controls. The mortality after fracture was independently predicted by age at fracture, male gender, and use of walking aids, for all 3 fracture groups (P < 0.05), and additionally by level of social dependence in the proximal femoral fracture group (P < 0.05). LEVEL OF EVIDENCE: level one, prospective cohort study. CONCLUSIONS: There is prolonged risk of premature mortality seen in both proximal femoral and proximal humeral fracture groups in the younger age cohorts, possibly as a result of concomitant medical comorbidities contributing to their premature deaths. Elderly patients sustaining proximal femoral fractures, despite high risk of mortality in the first year after injury, have survival approaching those of the general population in the longer term. Elderly patients who sustain wrist fractures have consistently better survival rates than the general population. This group of patients may be physiologically more robust than their age-matched peers in the general population.