A new tendon-lengthening technique using a tendon stripper for knee flexion contracture in a cerebral palsy patient

Abstract

Knee flexion contracture in a patient with cerebral palsy was treated by a new tendon-lengthening technique using a tendon stripper. The patient was a 10-year-old girl with mixed types of cerebral palsy related to a chromosomal anomaly. She was classified as level IV in the Gross Motor Functional Classification System with a bilateral 30° knee flexion contracture. The semitendinosus and gracilis muscle tendons were released from distal to proximal using a tendon stripper. The pulled-out muscle tendons were placed along and on their muscle portions. In addition, the semimembranosus tendon and the tendon of the biceps femoris were lengthened by an intramuscular lengthening until the contracture was released. After three weeks of casting, a long leg brace was made, and rehabilitation was started with full weight-bearing standing exercises. One year after the surgery, the improvement in maximum knee flexion contracture was maintained at 10° or less without severe progression or any complication. This new technique of using the tendon stripper on knee flexion contracture for a patient with cerebral palsy can be safe, feasible, and effective.

1. Introduction

Knee flexion contracture caused by hamstring spasticity and tightness is frequently observed in patients with cerebral palsy (CP). Severe knee flexion contractures make it more difficult for CP patients to walk unaided with uncomfortable alignment of the lower leg.¹ Conventionally, the distal tendinous portion of the hamstring is subjected to a Z-plasty procedure or fractional lengthening technique to lengthen the tendon. Tendon lengthening of the hamstrings can help patients walk smoothly.^2,3 We developed a new technique using a tendon stripper, slotted (Smith & Nephew, Andover, MA, USA) for improving knee flexion contracture for a CP patient. The tendon stripper is commonly used for harvesting hamstring tendons for anterior cruciate ligament reconstruction.⁴

In our technique, using the tendon stripper, the hamstring tendons are torn at the muscle part of the muscle-tendon junction and then pulled out. The pulled-out hamstring is then inserted back into the original muscle. It can be slid in at the muscle part, and then the length of the hamstring can be extended. Therefore, it is a method of artificially creating a muscle rupture and lengthening the muscle portion. Muscles are rich in blood vessels, and the muscle part that has been operated on follows the same healing process as that in muscle rupture. This is a relatively new concept in the field of tendon lengthening treatments. In this article, we report knee flexion contracture in a patient with CP, which was treated by the new tendon-lengthening technique using a tendon stripper.

2. Case report

A 10-year-old girl (height, 125.0 cm; weight, 18.7 kg) with mixed-type CP related to a chromosomal anomaly, first presented at our hospital when she was 3 years old. For the past seven years, she underwent physical therapy and showed no symptomatic improvement. Her walking ability declined, and she could hardly stand up without support and move by herself; hence, she was classified as level IV in the Gross Motor Functional Classification System. Moreover, since she had bilateral 30° knee flexion contracture, it became more difficult to practice walking. She felt pain when she stretched both knees and sufficient physiotherapy could not be performed recently. Therefore, surgical treatment was indicated for the maintenance of pain and functional limitations.

The ethics committee of Ibaraki Prefectural University of Health Sciences reviewed and approved this study (approval number: e88). Written informed consent was obtained from the patient's parent on her behalf for publication of this case and any accompanying images.

2.1. Surgical technique

Surgery was performed under general anesthesia with the patient in the prone position. Despite the general anesthesia, 30° flexion contractures were observed in both knees. The tendons on the lateral and medial sides were palpated in the area of the popliteal fossa and a longitudinal posterior incision of 5 cm was made in the distal central area of the thigh. The semitendinosus muscle tendon was identified and elevated on the medial side (Fig. 1a). The semitendinosus tendon was released from the distal to the proximal, using the open tendon stripper (Fig. 1b). Similarly, the gracilis tendon located just inferior to the position of the semitendinosus tendon was identified and released from the distal to the proximal using the tendon stripper. Each pulled-out muscle tendon was placed along and on its muscle portion. In addition, the semimembranosus tendon was treated with a double-level fractional lengthening. On the lateral side of the distal thigh, the tendon of the biceps femoris was also identified and then lengthened by an intramuscular lengthening, which was similar to the technique of lengthening the semimembranosus tendon, until the contracture was released. This surgery was performed bilaterally at the site of operation.

Fig. 1.

New tendon-lengthening technique using the tendon stripper on knee flexion contracture for a patient with cerebral palsy.

(a) The tendon of the semitendinosus muscle is identified and elevated on the medial side.

(b) The semitendinosus tendon is released from the distal to the proximal using the open tendon stripper.

2.2. Postoperative care

The patient's legs were cast immobilized in a position of 10° flexion of the knees for comfort and to await repair of the tendon and muscle. After three weeks of cast immobilization, a long leg brace was made for her new leg alignment and rehabilitation was started, including full weight-bearing standing exercises with a straight knee brace or bending movements of her legs voluntarily and passively. She was given a straight splint as a night brace. She continued general physiotherapy for three months. Eventually, she could walk with a gait trainer and was discharged without any complications. One year after the surgery, the improvement of the maximum knee flexion contracture was maintained at 10° or less without severe progression, and she was able to walk with support by pulling her hand.

3. Discussion

The semitendinosus and gracilis muscle tendons were released from the distal to the proximal using a tendon stripper. In addition, the semimembranosus tendon and the tendon of the biceps femoris were lengthened by an intramuscular lengthening until the contracture was released. One year after the surgery, the improvement of the knee flexion contracture was maintained at 10° or less, and the patient was able to walk with support.

Knee contracture and flexed-knee gait are well-known problems in spastic CP patients.¹ The common treatment option is surgical lengthening of the distal hamstrings with the goal of increasing the maximum knee extension angle and improving the gait pattern.^2,3 In this case, both the knee flexion contracture and walking ability improved as compared to the preoperative condition. Moreover, no complications occurred. Therefore, the new technique of using the tendon stripper for knee flexion contracture for a patient with CP can be safe, feasible, and effective. This method does not require suturing and is performed with a small incision.⁴ Therefore, it is a shorter operation that is much less invasive than the conventional method. Moreover, since the muscles are highly vascular and the contact area of the torn muscles is large, the healing process can be good. This method is also applicable to contractures after stroke or spinal cord injury.

As a complication of the tendon lengthening, some muscle weakness was reported. In a previous study, it took six months for the flexion strength of the knee joint to recover to pre-surgery levels after hamstring surgery.⁵ In the present case, the postoperative walking ability improved. However, since this method artificially ruptures the muscle, it is necessary to compare this technique with the conventional tendon-lengthening method with respect to changes in muscle strength in the future. Moreover, it is necessary to evaluate the clinical outcome of this technique by using it in more cases where tendon lengthening is required.

Declaration of interest

None.

Funding

The authors received no financial support for the research, authorship, and/or publication of this article.

Ethics approval and consent to participate

The ethics committee of Ibaraki Prefectural University of Health Sciences reviewed and approved this study (approval number: e88). Written informed consent was obtained from the patient's parent on behalf of the 10-year-old child for publication of this case and any accompanying images.

Authors’ contributions

HM conceived the study and participated in its design and coordination. All authors performed the operations. SN and HM analyzed the data and drafted the manuscript. All authors interpreted the data and participated in drafting the text and tables. All authors read and approved the final manuscript.