Introduction and Aims: Although skeletal muscles have remarkable potential for adaptation, the amount of muscle length increase during gradual limb lengthening is always less than the amount of bone lengthening. The purpose of this study was to analyse gene expression in skeletal muscle undergoing adaptation to limb lengthening.

Method: Ten adult goats were randomly divided into two groups of five animals. Group 1 underwent 20% (43–47mm) standard Ilizarov tibial lengthening and group 2 served as un-operated control. Muscle tissues from proximal myotendenous junctions of Peroneus Longus were harvested from the lengthened limb in the distraction group and corresponding limb in the control group and immediately snap frozen in liquid nitrogen. To screen for genes potentially associated with sarcomerogenesis, microarray technology was employed. Biotin labeled cRNA was hybridised to Affymetrix HU133A GeneChips, containing 22,284 gene transcripts. All created data files were analysed using computer software GeneSpring 5.0.

Results: In both groups, 5092 (23%) gene transcripts flagged present. Thirty-two of these transcripts were differentially expressed between distracted and control groups (p < 0.05). Represented by these transcripts were 12 known and three unknown genes, which were up-regulated in lengthened muscles by more than 2.0 fold. The substantially up-regulated genes identified were MYOZ2 (myozenin 2), MYL4 (embryonic myosin alkali light chain), MYL6 (myosin light polypeptide 6), CRYAB (crystalline), PFN2 (profiling 2), ARPP-19 (cyclic AMP phosphorprotein), TUBB2 (tubulin beta 2), PPP1R12 (protein phosphatase 1), RCOR (REST corepressor), LIM (LIM protein), FN1 (fibronectin 1), ACTC (alpha-actin), and hypothetical protein FLJ10111. Among the genes found to be up-regulated are genes involved in the myogenesis pathway. Myozenin 2 gene is associated with the signalling and activity of Calcineurin/Calsarcin that plays a significant role in muscle cell proliferation and myofiber type differentiation. Crystallin gene may be involved in promoting muscle survival during differentiation. The functionality of the remaining genes range from cytoskeletal organisation (TUBB2), cyto-skeletal structure (PFN2, MYL4, MYL6), cell adhesion and motility (FN1), muscle development and differentiation (FHL1 and LIM), intercellular adhesion and intermediate filament organisation (PNN), muscle contraction and relaxation (PPP1R12A), neuronal-specific gene silencing (RCOR), and PKA-dependent intracellular messaging (ARPP-19).

Conclusion: The findings suggest that tension stress observed during gradual limb lengthening using standard Ilizarov distraction protocol activates expression of genes involved in skeletal muscle growth, differentiation, and neogenesis. On-going studies involving immunohistochemistry, RT-PCR, and in situ hybridisation to confirm cellular localisation of up-regulated genes are underway.

Introduction and Aims: With a great progress in bone regeneration, muscle is currently regarded as a largest limiting factor for successful limb lengthening leading to joint contractures and fractures of distraction regenerate. The purpose of this study was to evaluate muscle architectural changes and potential mechanisms of joint contractures during limb lengthening.

Method: Nine mature goats underwent 20% unilateral tibial lengthening (0.25 mm x 3/day) and were sacrificed immediately upon completion of distraction. With the stifle (knee) and hock (ankle) joints fixed at similar angles, both limbs were disarticulated at the hip joint and submerged into 10% buffered formalin. Following tissue fixation, all tibial muscles were sequentially dissected and changes in muscle origin-to-incretion length, belly length, tendon length, myofibers length, and sarcomere length were analysed relative to the muscle measurements on the contralateral limb and bone lengthening. Muscle fiber length was assessed under stereoscopic magnification and sarcomere analysis was performed using laser diffraction.

Results: Thirteen muscles were identified for each limb. Anterior compartment consisted of two longitudinal and four pennate muscles, whereas posterior compartment had one longitudinal and six pennate muscles. Origin-to-insertion length measurements showed disproportion between the amounts of muscle and bone length increase with muscle-to-bone lengthening ratio ranging from 0.2 to 1.0. When assessed separately, muscle belly stretched more substantially (range, 11–24%) than muscle tendon (range, 3–14%). Longitudinal muscles showed better compliance to limb lengthening than pennate muscles. Origin-to-insertion, muscle belly, and tendon length increase for longitudinal muscles averaged 15%, 21%, and 11%, respectively, whereas for pennate muscles these parameters averaged 10%, 15%, and 6%, respectively. Although anterior pennate muscles showed higher proportion of muscle length increase than posterior pennate muscles, this difference was not significant. Lengthening of muscle fibers varied greatly, ranging from 0% to 88%. Fiber length of posterior muscles increased tremendously (average, 42%). This was associated with comparable increase in sarcomere length (average, 39%). Anterior muscles showed only 10% lengthening of the fibers. However, 12% reduction in sarcomere length indicated addition of new sarcomeres in series to accommodate increase in fiber length.

Conclusion: Different response of anterior and posterior muscles to distraction contributed greatly to the development of joint contractures. Posterior tibial muscles were predominantly pennate, larger in volume, and thus showed higher resistance to lengthening. Moreover, posterior muscle fibers incurred lengthening by sarcomere stretching, whereas anterior muscle fibers showed evidence of neosarcomerogenesis.

Introduction and Aims: Union of femoral shaft fractures in a shortened position is a recognised complication of spica cast treatment. Such shortening can only be assessed radiographically until the spica has been removed. The constraints of a spica cast complicate the imaging of the femur and may lead to error in assessing shortening. This study aims to quantify the magnitude of such error for application to clinical practice.

Method: A model for a spiral femoral fracture in a spica cast was devised. Shortening of the femoral segment through telescoping and angulation was controlled with a Wagner lengthening device external to the spica. Shortening from angulation and telescoping were varied and radiographic measurements compared with real measurements. The correlation between true and radiographic shortening of > 2cm was measured with the kappa value.

Results: There was good agreement between radiological and real shortening of > 2cm. Where shortening was present without angulation, the radiological measurement over-estimated the degree of shortening. The error increased with the amount of shortening. Angulation of more than 30 degrees caused the radiological measurement to under-estimate the true amount of segmental shortening.

Conclusion: This study suggests that radiological measurement of femoral shortening in a spica should reliably predict clinically significant shortening when there is less than 30 degrees of fracture angulation.

Introduction: Current classification schemes of fibular hemimelia concentrating on the radiographic appearance of the fibula do not adequately aid management of these patients. We reviewed our fibular hemimelia patient experience to devise a classification scheme which could serve as a better guideline for management decisions for this disorder.

Method: We reviewed the records/radiographs of all patients with the diagnosis of fibular hemimelia treated at our institution between 1957 & 1996. We excluded patients with PFFD, inadequate radiographs, or whose treatment was initiated elsewhere. We proposed a clinical management-oriented classification based on the presence/absence of a functional foot and overall limb shortening relative to the contralateral side (irrespective of the relative contributions of femoral & tibial shortening, or bilateral disease). The classification (with treatment guidelines) is:

Type I. Functional foot

Shortening 5% or less (none or epiphysiodesis)

Type II. Non-functional foot

Upper extremities functional (amputation)

A functional foot was defined as one which was or could be made plantigrade and stable with at least three rays.

Results: We identified 146 extremities in 122 patients with fibular hemimelia. 117 extremities were Type I (53 IA, 32 IB, 29 IC, and 1 ID), and 29 were Type II (28 IIA and 1 IIB). Limb length inequality remained proportional throughout growth, so that the distribution between groups did not change during growth.

Twenty-four patients had bilateral involvement. Twenty of 48 feet in these patients were Type II (nonfunctional). Nine patients with bilateral involvement had bilateral functional feet; these patients were short-statured, but were Type IA functionally.

The number of rays correlated directly with function: 100% of 5-rayed, 90% of 4-rayed, and 64% of 3-rayed feet were salvaged in this series. No feet less than 3-rayed were salvaged in this group; all such feet were associated with a completely absent fibula. Thirty-six of 63 limbs with completely absent fibula were classified as Type I. Eighty-two extremities in 65 patients have completed definitive management by virtue of skeletal maturity or amputation. A total of 39 extremities underwent Syme amputation, including 1 of 30 type IA, 1 of 11 type IB, 9 of 12 type IC, the single patient type ID, and all 27 type IIA deformities.

Conclusions: This classification system correlated well with the treatment required in our patients. While the amount of fibula present correlated with limb length inequality, 56% of patients in this series with absent fibula have been managed with limb salvage. The definition of a functional foot, and the boundary between multi-staged lengthening and amputation will remain an individual decision, but our classification scheme accurately predicted the amount of deformity present and the treatment required.

Introduction: Nonsteroidal anti-inflammatory medications such as Ibuprofen are commonly used to aid in the management of chronic pain in both children and adults. These medications are known to retard fracture consolidation and inhibit the formation of heterotopic bone in susceptible patients. We wished to determine the deleterious effects, if any, of the administration of therapeutic doses of Ibuprofen on the strength of regenerate bone in a caprine model.

Method: Twelve skeletally immature cross-bred goats were divided into two groups. In both groups, a standard four-ring, 6-wire Ilizarov apparatus was fixed to the tibia of one hindlimb and mid-diaphyseal corticotomy performed. After a five-day latency period, the operated tibiae were lengthened to 20% of their original length at rate and rhythm of 0.25mm TID. Consolidation time was standardized at 80 days. Group I received Ibuprofen at a dose of 20mg/kg BID PO during the entire postoperative period. Group II received no additional medication, and served as the control group. The animals were monitored for gatrointestinal intolerance, blood dyscrasias, and blood levels of Ibuprofen throughout the experiment. At the end of consolidation, the twelve lengthened tibiae and the contralateral tibiae were harvested for mechanical testing.

Results: In the medicated group, no adverse affects on the gastrointestinal or hematopoietic organ systems were identified. Blood Ibuprofen levels remained in the low therapeutic range during the course of the experiment (average levels 28.9 ug/ml at 1.5 hrs, 15.1ug/ml at 4 hrs., and 2.6 ug/ml at 8 hrs., after oral administration of Ibuprofen) .

One nonunion developed in each of the two treatment groups, and was unsuitable for mechanical testing. The remaining 22 tibiae (10 lengthened, and 12 contralateral unoperated, tibiae) were torqued to failure on the MTS testing machine. There were no significant differences between the unoperated tibiae of the Ibu-profen group and the unmedicated group measuring torsional toughness, stiffness, and strength. Similarly, there were no differences detected using these parameters between the lengthened tibiae of the medicated and unmedicated groups.

No adverse systemic affects were noted during the course of this experiment, in which low therapeutic levels of Ibuprofen were maintained for an average of 120 days. No affect on the torsional strength of the unoperated tibia was detected. No adverse affect on the torsional strength, stiffness, or toughness of the regenerate of the medicated group was noted compared to the control group.

Conclusions: The chronic administration of Ibuprofen was well-tolerated and did not adversely affect the strength of untreated or lengthened tibiae in this model.