Relative ability of young and mature muscles to respond to limb lengthening

Congenital Posteromedial Bowing of Tibia: Comparison of Early and Late Lengthening

BACKGROUND

Congenital posteromedial bowing of tibia (CPMBT), a rare anomaly, is characterized by a decreasing deformity and a gradually increasing limb shortening. Lengthening in CPMBT has not been studied extensively. Our series compares the duration and complications of lengthening in younger versus older children to determine early lengthening safety and benefits.

METHODS

We studied 28 tibial lengthenings performed by a single surgeon in 23 patients, divided into 2 equal groups of 14 segments: group A 5 years or younger (preschool) and group B above 5 years. All were lengthened with circular external fixators, of which 3 were lengthened over a nail. We measured preoperative (bo) and postoperative (po) sagittal, coronal, and oblique plane deformities, initial limb length discrepancy (LLD), percentage LLD (% LLD), amount of lengthening (AmtL), percentage lengthening (%L), external fixator duration (EFD), and external fixator index (EFI). We graded complications by Lascombes' criteria, results by Association for the Study and Application of the Methods of Ilizarov bone score.

RESULTS

The mean age was 8.8±7.1 years; the mean follow-up was 7.9 years. Group A had significantly greater bo-sagittal, coronal, and oblique plane deformities. Mean LLD (3.4 cm in group A vs. 4.1 cm in group B) was similar in both. Expected LLD at maturity (LLDM) using the multiplier method was greater than previously reported (mean, range in group A: 7.2 cm, 4.4 to 9.5 cm; group B: 5 cm, 2.5 to 9.7 cm). Though AmtL (3.5 and 4.1 cm) was similar in both, %L was 24% in group A and 15.7% in group B (P=0.002). EFD (116.6 days) and EFI (33.7 days/cm) were lesser in group A compared with group B (200.3 days, P=0.001; 50.2 days/cm, P=0.01). Lascombes' triple contract was fulfilled in 11/14 lengthenings in group A versus 3/14 in group B. Association for the Study and Application of the Methods of Ilizarov bone score was good and excellent in both groups (P=0.44).

CONCLUSIONS

In a large series of lengthenings in CPMBT, we found younger children presenting with large deformities and large projected length discrepancies could be safely lengthened with significantly lesser EFD and complications than in older children.

LEVEL OF EVIDENCE

Level IV-therapeutic study.

An MRI volumetric study for leg muscles in congenital clubfoot

PURPOSE

To investigate both volume and length of the three muscle compartments of the normal and the affected leg in unilateral congenital clubfoot.

METHODS

Volumetric magnetic resonance imaging (VMRI) of the anterior, lateral and postero-medial muscular compartments of both the normal and the clubfoot leg was obtained in three groups of seven patients each, whose mean age was, respectively, 4.8 months, 11.1 months and 4.7 years. At diagnosis, all the unilateral congenital clubfeet had a Pirani score ranging from 4.5 to 5.5 points, and all of them had been treated according to a strict Ponseti protocol. All the feet had percutaneous lengthening of the Achilles tendon.

RESULTS

A mean difference in both volume and length was found between the three muscular compartments of the leg, with the muscles of the clubfoot side being thinner and shorter than those of the normal side. The distal tendon of the tibialis anterior, peroneus longus and triceps surae (Achilles tendon) were longer than normal on the clubfoot side.

CONCLUSIONS

Our study shows that the three muscle compartments of the clubfoot leg are thinner and shorter than normal in the patients of the three groups. The difference in the musculature volume of the postero-medial compartment between the normal and the affected side increased nine-fold from age group 2 to 3, while the difference in length increased by 20 %, thus, showing that the muscles of the postero-medial compartment tend to grow in both thickness and length much less than the muscles of the other leg compartments.

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.

Structural changes in the lengthened rabbit muscle

This study evaluated the histological changes in muscle tissue after limb lengthening in skeletally mature and immature rabbits and assessed the most vulnerable level of striated muscle. Twenty-three male domestic white rabbits, divided into six groups, were operated on and different lengthening protocols were used in the mature and immature rabbits. The histopathological changes were analysed by a semi-quantitative method according to the scoring system of Lee et al. (Acta Orthop Scand 64(6):688-692, 1993). After the evaluation of the five main degenerative parameters (muscle atrophy, muscle nuclei internalisation, degeneration of the muscle fibre, perimysial and endomysial fibrosis, haematomas), it is evident that the adults lengthened at a rate of 1.6 mm/day showed more degenerative changes than those lengthened at 0.8 mm/day. The adult 1.6 mm/day lengthened group presented significantly higher damage in the muscle and lower regenerative signs compared with the young 1.6 mm/day lengthened group, according to the summarised degenerative scores.