Validation of the multiplier method for leg-length predictions on a large European cohort and an assessment of the effect of physiological age on predictions

PURPOSE

The Avon Longitudinal Study of Parents and Children (ALSPAC) prospective cohort was used to determine the accuracy of the Paley multiplier method for predicting leg length. Using menarche as a proxy, physiological age was then used to increase the accuracy of the multiplier.

METHODS

Chronological age was corrected in female patients over the age of eight years with documented date of first menses. Final sub-ischial leg length and predicted final leg length were predicted for all data points.

RESULTS

Good correlation was demonstrated between the Paley and ALSPAC data. The average error in prediction depended on the time of assessment, tending to improve as the child got older. It varied from 2.2 cm at the age of seven years to 1.8 cm at the age of 14 years. When chronological age was corrected, the accuracy of multiplier increased. Age correction of 50% improved multiplier predictions by up to 28%.

CONCLUSION

There appears to have been no significant change in growth trajectories of the two populations who were chronologically separated by 40 years. While the Paley data were based on extracting trends from averaged data, the ALSPAC dataset provides descriptive statistics from which it is possible to compare populations and assess the accuracy of the multiplier method. The data suggest that the accuracy improves as the patient gets close to the average skeletal maturity but that results need to be interpreted in conjunction with a radiological assessment of the growth plates. The magnitude of the errors in prediction suggest that when using the multiplier, the clinician must remain vigilant and prepared to perform a contralateral epiphyseodisis if the prediction proves to be wrong. The data suggest a relationship between the multiplier and menarche. There appears to be a factorisation and when accounting for physiological age, one needs to correct by 50% of the difference between chronological and physiological age.

A prejudiced view

The contemporary practice of orthopaedic surgery requires an evidence-based approach to support all medical and surgical interventions. In this essay, the author expresses a forthright, personal and somewhat prejudiced appeal to retain the legitimacy of clinical decision making in conditions that are rare, contain multiple variables, have a solution that generally works or has an unpredictable course.

Cite this article: Bone Joint J 2014;96-B:1002–4.

High-energy open tibial fractures in children

Between 2005 and 2010 ten consecutive children with high-energy open diaphyseal tibial fractures were treated by early reduction and application of a programmable circular external fixator. They were all male with a mean age of 11.5 years (5.2 to 15.4), and they were followed for a mean of 34.5 months (6 to 77). Full weight-bearing was allowed immediately post-operatively. The mean time from application to removal of the frame was 16 weeks (12 to 21). The mean deformity following removal of the frame was 0.15° (0° to 1.5°) of coronal angulation, 0.2° (0° to 2°) sagittal angulation, 1.1 mm (0 to 10) coronal translation, and 0.5 mm (0 to 2) sagittal translation. All patients achieved consolidated bony union and satisfactory wound healing. There were no cases of delayed or nonunion, compartment syndrome or neurovascular injury. Four patients had a mild superficial pin site infection; all settled with a single course of oral antibiotics. No patient had a deep infection or re-fracture following removal of the frame. The time to union was comparable with, or better than, other published methods of stabilisation for these injuries. The stable fixator configuration not only facilitates management of the accompanying soft-tissue injury but enables anatomical post-injury alignment, which is important in view of the limited remodelling potential of the tibia in children aged > ten years. Where appropriate expertise exists, we recommend this technique for the management of high-energy open tibial fractures in children.

Distal tibial physeal arrest after meningococcal septicaemia: management and outcome in seven ankles

Survivors of infantile meningococcal septicaemia often develop progressive skeletal deformity as a result of physeal damage at many sites, particularly in the lower limb. Distal tibial physeal arrest typically occurs with sparing of the distal fibular physis leading to a rapidly progressive varus deformity. There have been reports of isolated cases of this deformity, but to our knowledge there have been no papers which specifically describe the development of the deformity and the options for treatment. Surgery to correct this deformity is complex because of the patient's age, previous scarring and the multiplanar nature of the deformity. The surgical goal is to restore leg-length equality and the mechanical axis at the end of growth. Surgery should be planned and staged throughout growth in order to achieve the best functional results. We report our experience in six patients (seven ankles) with this deformity, who were managed by corrective osteotomy using a programmable circular fixator.

Angular deformity of the ankle with sparing of the distal fibula following meningococcal septicaemia: a case series involving 14 ankles in ten children

Progressive angular deformity of an extremity due to differential physeal arrest is the most common late orthopaedic sequela following meningococcal septicaemia in childhood. A total of ten patients (14 ankles) with distal tibial physeal arrest as a consequence of meningococcal septicaemia have been reviewed. Radiological analysis of their ankles has demonstrated a distinct pattern of deformity. In 13 of 14 cases the distal fibular physis was unaffected and continued distal fibular growth contributed to a varus deformity. We recommend that surgical management should take account of this consistent finding during the correction of these deformities.

The hip in osteochondrodysplasias: general rules for diagnosis and treatment

The management of hip pathology in osteochondrodysplasia (skeletal dysplasia) is complex and a multidisciplinary approach is vital. Thorough clinical assessment and knowledge of the natural history of the different disorders provides the basis for this.

Successful excision of neurogenic heterotopic ossification around the hip in cerebral palsy

We present the case of an 11-year-old girl with cerebral palsy, who developed bilateral spontaneous ankylosis of the hips as a result of heterotopic ossification following hip surgery. This was treated successfully by a combination of surgical excision, single dose radiotherapy and bisphosphonate treatment at five months from the time of the original surgery. A review of the literature shows that a combination treatment can be recommended in severe cases of heterotopic ossification to prevent recurrence. A review of neurogenic heterotopic ossification is presented. (Hip International 2005; 15: 123-7) KEY WORDS: Neurogenic heterotopic ossification, Hip reconstruction, Ankylosis, Cerebral palsy.

Dysplasia epiphysealis hemimelica: clinical features and management

Dysplasia epiphysealis hemimelica is a rare developmental bone dysplasia characterized by an osteocartilaginous tumor arising from an epiphysis. We reviewed the clinical and radiographic findings, including magnetic resonance imaging (MRI), of nine new patients with dysplasia epiphysealis hemimelica. The lower limb was involved in all cases with the ankle (talus) and knee (distal femur) being the most common sites. MRI was helpful in defining the site and extent of the osteocartilaginous mass and provided detailed images of associated joint deformity. Often there was a clear plane of separation between the lesion and the normal epiphysis. All cases were observed initially and showed progressive increase in size of the lesion with skeletal growth. Surgical excision was performed in five cases and proved to be difficult. We recommend excision of symptomatic localized, juxtaarticular lesions but do not recommend excision of articular lesions. Postoperative degenerative joint changes occurred in two patients.

Osteomyelitis of the scaphoid with sequestration of the primary ossification centre

An 8-year-old boy presented with Staphylococcus aureus osteomyelitis affecting the left (non-dominant) scaphoid. Surgical drainage resulted in the expulsion of the primary ossification centre as a sequestrum. Seven years later the wrist function was minimally impaired and X-rays showed complete ossification of the cartilage remnant with a relatively normal scaphoid.

Quantifying the kinematics of natural and prosthetic knee flexion

A new method has been developed for quantifying knee kinematics during flexion. This method was used to measure knee kinematics from lateral radiographs taken at different angles of flexion with the two femoral condyles superimposed in each image, thus standardizing the plane of flexion-extension. When applied to the radiogaphs of five healthy male volunteers (age range 21-26 years), it showed that flexion was accompanied by translation between the articular surfaces. Knee kinematics were also measured in five patients after total knee replacement (TKR) surgery with a Kinemax Modular Total Knee prosthesis (Howmedica, Warsaw, Indiana). In the TKR patients, a translation was detected in three out of the five patients. This indicates that the prosthesis is capable of restoring normal kinematics, but does not always do so.

Failure of trochanteric osteotomy in total hip replacement: a comparison of two methods of reattachment

A retrospective study was undertaken to assess the rate of trochanteric union after a primary Charnley total hip replacement. In one group the trochanter was reattached with Wrobleski spring wire, and in the second group with a Dall-Miles clamp. Non-union occurred in 29% of each group. The high rate of failure may have implications for morbidity and function. Alternative surgical approaches for total hip replacement should be considered.

A method for the kinematic evaluation of the knee following anterior cruciate ligament injury and reconstruction

A quantitative method for assessing the kinematics of the knee in the sagittal plane has been developed in order to evaluate the role of the anterior cruciate ligament following injury and reconstruction. Measurements were made on a series of lateral radiographs obtained at different angles of flexion with the limb weight-bearing and the foot and ankle rotated so that the condyles of the femur overlapped. The kinematics of the joint were then defined by recording the path of the tip of the medial tibial spine as flexion proceeded, using a coordinate system based on the femur. This method overcomes the problems inherent in quantifying knee kinematics by using the pathway of the centre of rotation. In an amputated knee, tibial positions could be specified to within approximately 1.2 mm. There were no significant differences between results obtained at the beginning and end of a six month period for the normal knees of two patients; the standard deviation of the measured tibial positions was approximately 1.6 mm.