Editorial
Challenge of Leg Length Discrepancy after Resection of Malignant Bone Tumors in Children
Ahmed Hamed Kassem Abdelaal*
Department of Orthopedic Surgery, Sohag University Hospital, Sohag, Egypt
*Corresponding author: Ahmed Hamed Kassem Abdelaal, Department of Orthopedic Surgery, Sohag University Hospital, Sohag, Egypt
Published: 23 Aug, 2017
Cite this article as: Abdelaal AHK. Challenge of Leg
Length Discrepancy after Resection of
Malignant Bone Tumors in Children.
Clin Surg. 2017; 2: 1603.
Editorial
Limb salvage has changed from being an exception to a standard practice in the management of
primary malignant bone tumors [1]. Limb salvage surgery is currently the gold standard of treatment
in bone sarcoma. It involves resection of the tumor with clear margins and then reconstruction of
the bony defect. The aim of limb salvage surgery is to preserve a limb with adequate function without
compromising the overall survival of the patient [2]. The majority of patients can be cured by the
virtue of multidisciplinary team including oncologists, radiation oncologists, surgeons, pathologists,
radiologists and involvement of patients in clinical trials [3]. Up until the 1970s, amputation was
the main form of treatment and yet the survival was only 11%. This dramatic improvement in the
survival of children with bone sarcomas in the past 30 years is attributed to the introduction of
chemotherapy for systemic treatment and a combination of improved imaging techniques, mainly
the introduction of MRI scan, better understanding of the pathophysiology of the disease, improved
surgical skills and advances in biomedical engineering has revolutionized the management and
the survival of children with bone sarcomas. At present 85% of patients will undergo limb salvage
surgery with survival ranging from 60% to 92% [4].
Leg length discrepancy “LLD” is a major challenge in the bony reconstruction of children
after resection of malignant bone tumors due to their continuing growth. The level of activity and
functional outcome depend to a large extent on the way of management of LLD as well as other
factors, especially most of the malignant tumors in children arise around the knee, especially in the
distal femur where the physis has the largest contribution to height growth of the child; 10 mm /
year, contributing to 70% of femoral growth or 54% of lower limb growth; followed by proximal tibia
where its physis contribute by about 46% of the lower limb growth by about 6mm/ year. Accepted
amount of LLD is a matter of debate; [5] while some authors had limited the accepted amount of
LLD to 20 or 30 mm, some others depended on the functional outcome to decide the ‘accepted’
LLD. Resection of the tumor will often involve excision of the growth plate and hence result in a
loss of growth. This expected LLD could be estimated from knowledge of the bone age of the child
and from growth charts [6]. In general, if the resection of the growth plate is expected to result in
limb length discrepancy of less than 30 mm then the limb can be lengthened by 10–20 mm during
reconstruction leaving an acceptable leg length difference of 10 mm – 20 mm at the completion of
growth. However if the anticipated leg length difference is >30 mm then allowance must be made
in the reconstruction for future growth or lengthening. The next challenge is to decide what type of
limb salvage surgery and there are several options, both endoprosthetic and biological. Expandable
Endoprosthetic replacement minimizes the challenge of lengthening if used, which is not always
the case. Absolute amount of LLD is another challenge, where some authors indicated amputation
when LLD at maturity is more than 20 cm, we believe that it is not only the absolute value of LLD
is enough to decide if it is ‘accepted’ or not, as in our postoperative rehabilitation protocol, when
the child has complete bone union, we encourage the physical activity and sports, thus LLD within
accepted range may present a hinder for the child in running and jumping, or other physical activity.
Another challenge is the time and site of lengthening, as regard timing; we prefer Paley
multiplier method [7] for the remaining growth to determine the time and expected LLD at
maturity to minimize number of elongations, it is reliable, easy applicable, high inter-observer
agreement. In case of reconstruction by expandable prosthesis, lengthening is performed according
to development of LLD, soft tissue allowance, on frequent, timely adjusted intervals, the less amount
of lengthening each time is preferred to minimize soft tissue complications, but it would increase the
number of lengthening procedures till skeletal maturation. When reconstruction is performed using
biological techniques, i.e., autoclaving, pasteurization, or freezing, we prefer to perform lengthening
on the ‘virgin’ bone, i.e., if the reconstructed bone is the femur, we lengthen the tibia, and vice versa, because the full revitalization of the biologically recycled bone takes
long time, up to six years in case of using freezing techniques [8]. In
addition, the regenerate is more biologically powerful in the virgin
bone, doesn’t interfere with the fixation procedure, and doesn’t mask
local recurrence. Lengthening is performed by distraction osteogenesis
using Ilizarov device, or Taylor Spatial frame TSF, distraction usually
starts at the usual time after the operation. Lengthening through the
virgin bone usually leads to knee joint unlevelling, which has no or
minimal effect on the functional outcome in our experience.
References
- Hong AM, Millington S, Ahern V, McCowage G, Boyle R, Tattersall M, et al. Limb preservation surgery with extracorporeal irradiation in the management of malignant bone tumor: the oncological outcomes of 101 patients. Ann Oncol. 2013;24(10):2676-80.
- Abed R, Grimer R. Surgical modalities in the treatment of bone sarcoma in children. Cancer Treat Rev. 2010;36(4):342-7.
- Steinau HU, Daigeler A, Langer S, Steinsträsser L, Hauser J, Goertz O, et al. Limb salvage in malignant tumors. Semin Plast Surg. 2010;24(1):18-33.
- Wilkins RM, Cullen JW, Odom L, Jamroz BA, Cullen PM, Fink K, et al. Superior survival in treatment of primary nonmetastatic pediatric osteosarcoma of the extremity. Ann Surg Oncol. 2003;10(5):498-507.
- Gurney B. Leg length discrepancy. Gait Posture. 2002;15(2):195-206.
- Cool WP, Grimer RJ, Carter SR, Tillman RM, Davies AM. Longitudinal growth following treatment for osteosarcoma. Sarcoma. 1998;2(2):115-9.
- Paley D, Bhave A, Herzenberg JE, Bowen JR. Multiplier method for predicting limb-length discrepancy. J Bone Joint Surg Am. 2000;82- A(10):1432-46.
- Tanzawa Y, Tsuchiya H, Shirai T, Hayashi K, Yo Z, Tomita K. Histological examination of frozen autograft treated by liquid nitrogen removed after implantation. J Orthop Sci. 2009;14(6):761-8.