Introduction

Research studies have established mathematical correlations between the lengths of bone segments and the possible biomechanical implications of these correlations. The Lucas sequence comprises a series of integers that adhere to the same recurrence relation as the Fibonacci sequence; it differs in that it can start with any two initial integers. The purpose of this study is to determine whether segmental lengths of the foot height, tibia, femur, and upper body follow a Lucas sequence pattern.

Objectives

The purpose of this study was to compare the results and complications of tibial lengthening over an intramedullary nail with treatment using the traditional Ilizarov method.

External fixation is widely used in orthopaedic and trauma surgery. Infections around pin or wire sites, which are usually localised, non-invasive, and are easily managed, are common. Occasionally, more serious invasive complications such as necrotising fasciitis (NF) and toxic shock syndrome (TSS) may occur.

We retrospectively reviewed all patients who underwent external fixation between 1997 and 2012 in our limb lengthening and reconstruction programme. A total of eight patients (seven female and one male) with a mean age of 20 years (5 to 45) in which pin/wire track infections became limb- or life-threatening were identified. Of these, four were due to TSS and four to NF. Their management is described. A satisfactory outcome was obtained with early diagnosis and aggressive medical and surgical treatment.

Clinicians caring for patients who have external fixation and in whom infection has developed should be aware of the possibility of these more serious complications. Early diagnosis and aggressive treatment are required in order to obtain a satisfactory outcome.

Cite this article: Bone Joint J 2015;97-B:1296–1300.

Internal lengthening devices in the femur lengthen along the anatomical axis, potentially creating lateral shift of the mechanical axis. We aimed to determine whether femoral lengthening along the anatomical axis has an inadvertent effect on lower limb alignment. Isolated femoral lengthening using the Intramedullary Skeletal Kinetic Distractor was performed in 27 femora in 24 patients (mean age 32 years (16 to 57)). Patients who underwent simultaneous realignment procedures or concurrent tibial lengthening, or who developed mal- or nonunion, were excluded. Pre-operative and six-month post-operative radiographs were used to measure lower limb alignment. The mean lengthening achieved was 4.4 cm (1.5 to 8.0). In 26 of 27 limbs, the mechanical axis shifted laterally by a mean of 1.0 mm/cm of lengthening (0 to 3.5). In one femur that was initially in varus, a 3 mm medial shift occurred during a lengthening of 2.2 cm.

In a normally aligned limb, intramedullary lengthening along the anatomical axis of the femur results in a lateral shift of the mechanical axis by approximately 1 mm for each 1 cm of lengthening.

Between October 2001 and September 2009 we lengthened 242 lower-limb segments in 180 patients using the Intramedullary Skeletal Kinetic Distractor (ISKD). Mechanical failure was defined either as breakage of the ISKD or failure of the internal mechanism to activate. Retrieved nails which failed mechanically were examined by the manufacturer for defects. In all, 15 ISKDs in 12 patients (13 limbs) failed mechanically representing an overall failure rate of 6.2%, with fracture of the device occurring in ten of the 15 failures. Two nails in one patient failed to lengthen and had to be replaced. The manufacturer detected an error in the assembly of the nail, which prompted a wide recall. One nail jammed after being forcefully inserted, and two nails failed to lengthen fully. Lengthening was achieved in all 12 patients, although three required a second operation to exchange a defective nail for a new, functioning device.

The ISKD is a complex mechanical device which lengthens by the oscillation of two telescopic sections connected by a threaded rod. The junction between these sections is surrounded by a keyring collar. This keyring collar is the weakest part of the device.

Introduction: Achondroplasia is a form of rhizomelic dwarfism. Even if patients can compensate for their short arms through the mobility in their spine during the childhood, the flexibility in their spine becomes less with aging. Because of that, as they get older they experience problems in maintaining personal hygiene especially in reaching the back. In addition putting on socks and tying their own shoes might become difficult.

Methods: Inclusion criteria included any patient with a history of achondroplasia who had undergone humeral lengthening in the proximal part of the humerus (just distal to deltoid muscle insertion). Patients who had distal humeral (supracondylar) osteotomy and/or who received other than monolateral external fixator were excluded from the study. 50 humeri of 25 patients with achondroplasia were lengthened using Orthofix mono-lateral external fixator utilizing proximal humeral osteotomy. Sixteen patients were female and nine were male. Mean age was 15.4 months (range, 9.6 – 21.8). Lengthening was started at 7th day. Patients were lengthened at 1/4 turn four times a day reaching 1 mm/day. Physical therapy was performed 3 times a week. Goal of lengthening was around 10 cm or whatever length the patient could tolerate. Patients wore Sarmiento type fracture brace 4–6 weeks after the fixator was removed.

Results: Mean follow-up time from surgery was 51.5 months (range, 6 – 143 months). Mean follow-up time from removal of external fixator was 44.7 months (range, 0 – 135 months). Average external fixation time was 7.3 months. In 20 humeri it was noted that the average duration of lengthening was 4.2 months (range, 3 – 5.8 months). A mean lengthening of 9.3 cm was obtained (range, 4.3 – 12.8 cm). At latest follow-up range of motion was not compromised due to lengthening. All patients had similar ROM before and after the surgery. Complications included radial nerve palsy in 8, pin tract infection in 7, fracture through regenerate in 3, premature consolidation in 1, nonunion in 1, delayed healing in 1. Radial nerve palsy recovered without intervention in one case. In others it recovered uneventfully after successful decompression. No complications at all occurred in 30 cases.

Discussion: Fifty humeri of 25 patients with achondroplasia received successful humerus lengthening as part of extensive limb lengthening offered in our center. None of the patients had long term sequela, and all radial nerve palsies recovered. Patients were satisfied with the lengthening and found it easier to undergo through humerus lengthening compared to lower limb lengthening. After a mean follow-up time of almost 4 years, these patients returned back to their normal lives with optimum upper limb function with no hindrance in maintaining personal hygiene, putting on socks or tying their own shoes.

Introduction and Aims: We propose a new, simple, and universal method to predict adult height: the Height Multiplier Method. Our aim was to calculate height multipliers from various databases and validate their use for height prediction.

Method: Standard growth charts, based on a diverse population, were published by the Centres for Disease Control and Prevention (CDC) in 2000. Height multipliers (M) for boys and girls were calculated by dividing the height at skeletal maturity (Htm) by the present height (Ht) (M = Htm/Ht) for each age, gender, and height percentile using CDC data. These multipliers were compared with multipliers derived from various height databases of 28 boys and 24 girls. The accuracy of the multipliers was tested on individual longitudinal data sets from 52 normal children.

Results: The average CDC-derived multipliers were significantly different at each age for boys and girls, but within gender, different percentiles at each age were very similar. These multipliers were very similar to multipliers derived from each of the databases. For predictions based on individual data sets from 52 children, the median, 90%, and standard deviation of absolute error prediction (AEP) were calculated. Boys’ median AEP ranged from 1.4–4.3cm; 90% AEP ranged from 1.8–8.3cm. Girls’ median AEP ranged from 0.68–4.38cm; 90% AEP ranged from 1.5–10.6cm.

Conclusion: The Height Multiplier Method of stature prediction is as accurate as CDC growth charts when based on single-height measurements and is similar in accuracy to other methods. The Height Multiplier Method has the advantage of percentile, race, nationality, and generation independence. Growth charts have the advantage of showing trends over time.

Introduction and Aims: We evaluated the incidence, cause, predisposing factors, and treatment outcomes of fractures associated with limb lengthening. Our aim was to improve the prevention and treatment of these fractures.

Method: We studied 70 patients with 80 fractures retrospectively identified from a database of all patients who had undergone limb lengthening at our institution between 1987 and 1999. Fractures were analysed according to bone fractured, classification of fracture, timing, diagnostic group, treatment, and residual deformity. Treatment of fractures was individualised for each patient according to the specifics of fracture occurrence. A residual deformity was defined as shortening > 1cm or angulation of clinical significance > six degrees.

Results: Eighty fractures occurred with 986 lengthenings in 650 patients, yielding an overall fracture rate of 8.1%. Seventy-four percent of fractures occurred in regenerate bone or at the host-regenerate junction. Eighty-one percent of fractures occurred out of frame. Four percent occurred at time of frame removal, 16% with the frame still in situ. Majority of fractures sustained out of frame (84%) were through regenerate bone; majority in frame (85%) were through non-regenerate regions, 69% of these through a pinhole. Patients with dysplasia and those undergoing lengthening because of congenital syndromes had a higher incidence of fracture (11% and 19%, respectively) and a higher incidence of residual deformity (RD) (47% and 45%, respectively) than did the rest of the patient population. Overall incidence of RD was 38%. Rate of RD was 23% for fractures occurring in frame, 67% at removal time, and 40% for those sustained after removal.

Conclusion: Majority of fractures occur out of frame through regenerate bone. Most non-regenerate fractures occur at pin site. Operatively and non-operatively treated fractures had similar rates and magnitudes of residual deformity. Congenital and dysplastic had higher rates than post-traumatic (possibly more ambitious surgical goals, smaller bone diameter, more limiting soft tissues).

Introduction and Aims: Distraction osteogenesis can be used to stimulate healing in hypertrophic non-unions (HNU). We evaluated the use of closed (without opening the non-union) Ilizarov distraction for HNU with associated angulation, malrotation, and shortening.

Method: Sixty-seven consecutive patients (mean age, 38.3 years) with 71 HNU were treated (1988–2001) using Ilizarov distraction. Patients had undergone an average of five previous operations. HNU classified as stiff (< 5 degrees mobility) were distracted, and those classified as partially mobile (5–20 degrees mobility) were first compressed and then distracted.

Results: Non-unions included: 59 tibiae, six femora, two radii, and five ankle arthrodeses. Mean limb length discrepancy, 3.5cm; mean deformity, 16°; history of osteomyelitis, six cases. Closed distraction alone was successful in achieving union in 61 cases (86%) (mean follow-up, six years; mean time to union, eight months). Union rate was 91.6% (55 of 60 cases) for stiff HNU and only 54% (six of 11 cases) for partially mobile HNU. Distraction treatment alone failed to achieve union in 10 cases. In seven, union was achieved after bone grafting. Two required resection of infected non-union with bone transport to achieve union. One had persistent non-union. There were numerous superficial pin infections and three deep infections. Two cases had deformity at proximal tibial lengthening osteotomy site.

Conclusion: Closed distraction is safe and reliable for stimulating union in stiff HNU. It is especially effective in a scarred limb that has undergone previous operations. It allows for simultaneous correction of deformity and length. Main disadvantage is lengthy time spent in external fixator.

Introduction and Aims: Congenital femoral deficiency (CFD) can be managed by femoral lengthening using callotasis with external fixation. A common complication is fracture with angular deformation soon after fixator removal. We developed a novel technique to overcome this complication using intermedullary stabilisation. Special hand reamers are needed to re-establish medullary canal blocked by cortical plates around previous external fixator pin sites and not yet recanalised regenerate bone.

Method: Since 2000, we treated nine of these fractures in children with an average age of 5.4 years. The children had spent an average of 22 weeks in a fixator, gaining a mean of 7cm of length. Most fractures occurred as ‘spontaneous’ events at a mean of three weeks after fixator removal, resulting in a transverse fracture through the regenerate bone, host-regenerate interface, or proximal pin sites. All were stabilised with intermedullary nailing.

Results: Union was achieved satisfactorily in approximately six weeks. No serious complications, such as infection, avascular necrosis, or non-union, occurred. All bones were successfully realigned, and the mean loss of length was only 0.7cm.

Conclusion: Careful surgical technique, using specific operative steps described (including use of flexible hand reamers to create canal, small percutaneous osteotomies to allow proper reduction, and Rush pins for stabilisation) has achieved good results. We recommend this approach to surgeons involved in the management of fractures occurring after fixator removal.

Introduction and Aims: Fibular hemimelia presents a problem with leg length discrepancy and equinovalgus foot deformity. Our protocol is to simultaneously treat both problems, with the goals of equalising limb length and achieving a plantigrade painless functional foot.

Method: Seventy-eight patients with fibular hemimelia underwent 92 lengthenings and foot deformity correction. Equinovalgus foot deformity was corrected by four different methods in 67 cases: distraction, soft tissue release, release plus supramalleolar and/or subtalar osteotomy, and fibular transport.

Results: Goals of lengthening and foot deformity correction were achieved in all cases. Foot deformity recurred in 19 patients and was retreated: 9/16 (56%) distraction cases, 4/18 (22%) soft tissue release cases, 2/28 (7%) release plus osteotomy cases, and 4/5 (80%) fibular transport cases. Genu valgum developed in many cases with no or partial anlage resection. Genu valgum did not develop in any cases with complete anlage resection. Final results based on functional and radiographic evaluation: 46 excellent, 28 good, 18 fair. Final result did not correlate with number of rays in foot.

Conclusion: Limb length discrepancy and foot deformity can be successfully treated by simultaneous lengthening and foot deformity correction. Soft tissue release plus osteotomy and complete anlage resection yielded best results. Lengthening reconstruction surgery is an excellent alternative to ablative surgery and prosthetic fitting for patients with all severities of fibular hemimelia.

Introduction: The management of post-traumatic, tibial, segmental, skeletal defects is a difficult problem that often requires complex approaches for successful limb salvage. Bone transport and acute shortening with subsequent relengthening are two techniques that have been made possible using Ilizarov’s methods.

Aim: To determine whether either technique offers any intrinsic advantage relative to the other.

Methods: We carried out a retrospective review of charts and radiographs of 42 patients with post-traumatic tibial defects that had been managed using Ilizarov’s methods. The follow-up period averaged 26 months. We selected patients with defects between 3 cm and 10 cm to provide a suitable comparison. The patients were divided into two groups of 21 each, treated either by bone transport or acute shortening.

Results: The defects averaged 7.0 cm in the transport group and 5.8 cm in the acute shortening group. The transport group averaged 12.5 months in the fixator; the acute shortening group averaged 10.1 months. However, the external fixation index was virtually identical in the two groups (mean 1.8 months/cm in the transport group and 1.7 months/cm in the acute shortening group). The complication rate, radiographic results, and functional results were slightly better in the acute shortening group.

Conclusions: Both techniques demonstrated excellent results overall and the external fixation index was nearly identical for these related methods. The final results after treatment by acute shortening were found to be slightly better than the final results following bone transport. There may be a slight advantage to the use of this technique for smaller defects in properly selected patients.