Aims

Our aim was to investigate the predictive factors for the development of a rebound phenomenon after temporary hemiepiphysiodesis in children with genu valgum.

Permanent growth arrest of the longer bone is an option in the treatment of minor leg-length discrepancies. The use of a tension band plating technique to produce a temporary epiphysiodesis is appealing as it avoids the need for accurate timing of the procedure in relation to remaining growth. We performed an animal study to establish if control of growth in a long bone is possible with tension band plating. Animals (pigs) were randomised to temporary epiphysiodesis on either the right or left tibia. Implants were removed after ten weeks. Both tibiae were examined using MRI at baseline, and after ten and 15 weeks. The median interphyseal distance was significantly shorter on the treated tibiae after both ten weeks (p = 0.04) and 15 weeks (p = 0.04). On T₁-weighted images the metaphyseal water content was significantly reduced after ten weeks on the treated side (p = 0.04) but returned to values comparable with the untreated side at 15 weeks (p = 0.14). Return of growth was observed in all animals after removal of implants.

Temporary epiphysiodesis can be obtained using tension band plating. The technique is not yet in common clinical practice but might avoid the need for the accurate timing of epiphysiodesis.

Cite this article: Bone Joint J 2013;95-B:855–60.

Introduction

A prospective study was done using Kirschner (K) wires to internally fix capitellum fractures and its results were analysed.

Introduction: The use of anterior vertebral staples in the fusionless correction of scoliosis has received increased attention in recent literature. Several animal studies have shown stapling to be effective in modulating vertebral growth. In 2005 Betz (1) published the only clinical series to date. Despite the increasing volume of literature suggesting the efficacy of this treatment, little is known about it’s biomechanical consequences. In 2007 Puttlitz (2) measured the change in spinal range of motion after staple insertion in a bovine model. They found a small but statistically significant decrease in range of motion in axial rotation and lateral bending. The clinical significance of this is questionable as the differences were only a few degrees over three vertebral levels. A well designed biomechanical evaluation of the effects of staple insertion on spinal stability is needed. The aim of this study was to evaluate the effect of insertion of a laterally placed anterior vertebral staple on the stiffness characteristics of a single motion segment.

Methods: Four-pronged shape memory alloy staples were inserted into fourteen individual bovine thoracic motion segments. A displacement controlled six degree-of-freedom robotic facility was used to test control and staple constructs through a pre-determined range of motion in flexion, extension, lateral bending, and axial rotation. All data were synchronised with robot position data and filtered using moving average methods. The stiffness in each condition was calculated in units of Nm/degree of rotation. Paired t-tests were used to compare results.

Results: Stiffness measurements in the control condition correlated with previously published measures (3). A significant decrease in stiffness (p< 0.05) following staple insertion was found in flexion, extension, lateral bending away from the staple, and axial rotation away from the staple. Stiffness for axial rotation towards the stapled side was significantly greater than for away. A near significant increase in lateral bend stiffness away from the staple compared with towards was also seen.

Discussion: These results suggest that staple insertion consistently decreased stiffness in all directions of motion. This is contrary to the results of Puttlitz (2), which reported a reduced range of motion (i.e. increased stiffness) for some motions using moment-controlled testing. This decrease in stiffness could not be explained by changes in anatomy or tissue properties between specimens, as each stapled motion segment was compared with its own intact state. Addition of the staple would intuitively be expected to increase motion segment stiffness, however we suggest that the staple prongs may cause sufficient disruption to the vertebral bodies and endplates to slightly reduce overall stiffness. Hence, growth modulation may be achieved through physical disruption of the endplate, rather than static mechanical stress. Further research is planned to investigate the proportion of load carried by the staple during spinal movement and the anatomical effect of the staple on the physis. In conclusion, anterior vertebral stapling causes a slight but significant decrease in the stiffness of treated motion segments.

Introduction: Prior to skeletal maturity temporary hemiepiphyseal stapling is a treatment method for angular deformities of long bones. The purpose of this study is to investigate the effects of temporary hemiepiphyseal stapling on the bone geometry and histology of physis.

Materials & Methods: Proximal medial epipyseal stapling of the right tibia were done in 46 New Zealand rabbits. 23 of them were euthanized at the end of 3 weeks. For the remaining 23 rabbits staples were fixed subperiostally (group A) in 11, and extraperiosteally (group B) in 12 rabbits. After 3 weeks the staples removed and the rabbits were euthanized at the end of 6 weeks. Bromodeoxyuridine used to evaluate cellular activity of the growth plate. Radiographs utilized for bone alignment.

Results: The articular surface-diaphysis angle was significantly increased at the end three weeks when compared to controls (27.7° vs. −1.5°, p:0.001). Cellular activity was decreased but preserved in the stapled tibias. At the end of six weeks while the angular deformity was worsening in group A 22.9° vs. 35.6°, p:0.001) it was improving in group B (23.2 ° vs. 14.6°, p:0.001). Bone tissue bridging the growth plate was noted in group A. Cellular activity in the group B was higher than group A at the end of six weeks.

Conclusion: Hemiepiphyseal stapling causes decreased cellular activity at the growth plate, which leads to angulation. With removal of staples, increased cellular activity at the growth plate results in the improvement of the deformity if staples were inserted extraperiosteally. Temporary extraperiosteal hemiepiphyseal stapling could be used as a safe and effective method for treatment of angular deformities prior to skeletal maturity.

We report the results of medial physeal stapling in 16 knees with primary genu valgum and 27 with secondary genu valgum. In the primary group, stapling was undertaken at a mean chronological age of 12 years in girls and 13 years in boys. The medial femoral physis was stapled in ten knees and the medial femoral and tibial physes in six knees. At skeletal maturity, all patients had excellent or good leg alignment. Secondary genu valgum is due to skeletal dysplasia, haematological or endocrine disorders, or to juvenile chronic arthritis. Stapling was at a mean chronological age of 11 years in girls and 14 years in boys. The medial femoral physis was stapled in 13 knees, the medial tibial physis in three and both in 11 knees. At skeletal maturity, 85% had excellent or good leg alignment, and correction had occurred within one year. Two of the poor results were due to staple extrusion from osteoporotic bone, and two to overcorrection. Rebound growth was minimal and unpredictable after the removal of staples. Medial physeal stapling is a suitable method of treatment for both primary and secondary genu valgum in late childhood and in adolescence. At least one year of knee growth is required to achieve correction, and care is needed to avoid overcorrection of the secondary genu valgum

Forty-nine patients treated by epiphysial stapling for idiopathic genu valgum are reviewed. The children were aged from eleven to fourteen and a half years. The severity of the condition and subsequent correction were assessed by measuring the inter-malleolar distance. Results show that femoral stapling is the treatment of choice for most patients with inter-malleolar separation of up to 12-5 centimetres. The optimum age for stapling for both boys and girls is eleven and a half years. Stapling of both epiphyses is advised for those patients presenting late, for example, between thirteen and fourteen and a half years, or where the deformity is greater than 12-5 centimetres of separation. Correction rarely takes more than one year, and was cosmetically satisfactory in all cases. The operation is virtually free from complication except for a tendency for the scars to be broad and conspicuous. Stapling has proved to be a safe, effective and predicatable operation for idiopathic genu valgum

1. Arrest of growth at one proximal tibial epiphysis of young rabbits was obtained by stapling.

2. Radiopaque markers allowed the subsequent growth of both proximal and distal epiphyses of the experimental and contralateral tibiae and of both lower femoral epiphyses to be followed radiographically.

3. The reduction in the normal deceleration of growth rate at the distal epiphysis found after epiphysiodesis of the proximal epiphysis was again observed.

4. This change in growth rate was not encountered in the distal femoral epiphysis lying adjacent to the stapled tibial epiphysis.

5. Removal of the staples after the change in growth rate had become established at the distal tibial epiphysis was followed by a return to an approximately normal growth rate by both proximal and distal epiphyses.

6. It is concluded that a direct relationship exists between the additional growth at the uninjured epiphysis and the deficiency in growth obtained at the stapled epiphysis, and that this change in growth rate is limited to the experimental tibia.

1. Thirty-three patients who had had stapling of the lower femoral and upper tibial epiphysis to correct inequality of the leg lengths were reviewed after maturity. The staples were inserted so that correction of the disparity would coincide with termination of growth.

2. The predicted corrections were found to be inaccurate. The error was 47 per cent in girls operated on between ten and twelve and 51 per cent in boys between ten and thirteen. In older children the prediction was more accurate.

3. Despite the inaccuracy of prediction only four patients were left with shortening of more than 3·5 centimetres.

4. Complications of the operation were deformity, ligamentous laxity, subjective symptoms and necessity for further operation.

5. Only one girl had a serious deformity–genu recurvatum of 25 degrees. Half the patients had minor degrees of hyperextension.

6. The causes of the complications are discussed and suggestions made how their incidence might be reduced.

7. It is concluded that the operation of stapling the epiphyses around the knee of the long leg has a small but useful part to play in the correction of inequality of leg lengths. It should be confined to tall boys over thirteen and girls over twelve.