Preventing instability of the Taylor Spatial Frame (TSF) during a strut change.

SUMMARY: During treatment with a Taylor Spatial Frame, some of the struts may need to be exchanged for one of a different length. An extra "seventh" strut is usually added to the frame during this procedure. This article describes a "technical trick" to ensure stability during a strut change. The frame was stable whenever the orientation of the "acute ring-strut" of the temporary strut matched that of the strut being exchanged. Clinicians must anticipate that instability can exist during strut changes, and this will depend on the particular configuration and position of the frame. Applying the rule indentified in this article may prevent instability, pain, and tissue damage.

Recovery of muscle strength and power after limb-lengthening surgery.

OBJECTIVE: To report muscle strength, power, and function after limb-lengthening surgery performed by using the Ilizarov technique. DESIGN: Prospective, longitudinal observational study of a cohort of consecutive patients who underwent limb-lengthening distraction followed up for 2 years after surgery. SETTING: National Health Service hospital specializing in orthopedic surgery. PARTICIPANTS: Patients (N=16) who had undergone limb-lengthening surgery performed by using the Ilizarov method (11 men, 5 women; mean age=27 y; range, 13-56 y). INTERVENTIONS: None. MAIN OUTCOME MEASURES: Muscle strength and power were assessed by using 2 validated measures: isokinetic concentric strength of the quadriceps and hamstrings measured by using a dynamometer and leg extensor power. Measures were recorded preoperatively and at 6, 12, and 24 months after the completion of lengthening. Function was measured by 2 timed tests of functional performance: stair climbing and sit-to-stand. RESULTS: Overall results were good with high reports of function and satisfactory clinical examination. Both concentric muscle strength and leg power showed a clear pattern of decreased muscle strength at 6 months after frame removal, improving throughout the study period until it was within 3% of the preoperative value at 2 years. By 2 years, self-reported function and ability to complete timed functional tests had returned to or improved on the preoperative values. Muscle strength remained slightly below the preoperative value; this was more pronounced in the quadriceps than the hamstrings. There was no association between muscle strength and the amount of lengthening that had been undertaken. CONCLUSIONS: This study suggests that there is a small residual decrease in muscle strength and power after limb-lengthening surgery but that these do not adversely impact on a patients' ability to perform everyday functional activities.

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.