Prosthetic Rehabilitation of Bilateral Tibial Hemimelia: A Case Report

Introduction

Tibial hemimelia or congenital longitudinal deficiency of tibia is a very rare health condition with an incidence of 1 in 1,000,000 live births.^1-4 It presents with a wide range of pathology, ranging from a hypoplastic tibia to complete absence of the tibia. Flexion contracture of the knee, ankle joint instability, and dimple overlying the proximal tibial region are common. Rigid varus, supination deformity, and marked shortening of the first metatarsal are frequently associated with other medial ray defects.⁵ The ankle ranges may be normal motion or can vary with fixed equino-varus deformity at the other end. It can be unilateral or bilateral, with an estimated 30% of cases being bilateral.^6-8 The physical deficiency leads to functional deficiency as the individual grows. Amputation and reconstruction procedure is rarely opted.⁸ Reconstruction is a complex long-term treatment modality with a high rate of complications, which have a great impact on children’s social life and psychology.⁵ Prosthetic management of tibial hemimelia can help in achieving mobility as well as acceptable physical appearance. Surgical procedure may enhance the proper fitting of prosthesis in which the individual can feel more comfortable.

Case Presentation

The subject was a 19-year-old female who was diagnosed with bilateral tibial hemimelia postnatally. She was referred to Swami Vivekanand National Institute of Rehabilitation and Research (SVNIRTAR), Cuttack, India for rehabilitation through a team of social workers. As a female with bilateral tibial hemimelia, she had difficulty in accepting the body image positively. Besides this, she was a very active and could perform all her day-to-day life activities. The limbs were quite odd due to the deformities and there was no proper foot wear available to protect the soft skin of legs and both feet. Walking long distance was very difficult for her and she was preferring wheel chair for long distance locomotion which was restricting her social participation. Pleasant appearance and a good gait pattern was her felt need from the childhood with an aim of leading a normal life (Figure 1).

Fabrication Procedure

1. Evaluation: The subject was evaluated thoroughly. Physical examination showed normal vital signs. It was revealed that the subject was having a type- II tibial hemimelia. Rigid deformities like flexion contracture of knees, severe internal rotation and adduction of both feet along with alteration in total length of both the limbs were the cause of deviated and odd gait pattern. Muscle strength of upper extremities, trunk and hips were 4+ out of 5. The subject was mentally very strong and an active participant in extracurricular activities.

2.  Prescription: The subject was prescribed with a pair of assistive devices (knee pads with soft liners with modified suspension straps with rocker sole) and bilateral extension prostheses (Ischial and partial distal weight bearing sockets with soft inner liner with modified transfemoral suspension system with 4-bar linkage polycentric mechanical knee joint with solid ankle cushion heel (SACH) foot with a pair of sports shoes) (Figure 2).

3.  Limb impression technique:

Assistive device - The cast was wrapped over only the distal part of the limb up to 6 to 8 inches from the distal surface and the subject was asked to bear the weight on it as she normally stands.

Extension prosthesis - The cast was wrapped over the limb one by one. Impressions for ischial weight bearing were applied on the proximal area of the limb and for partial distal weight bearing design, the subject was asked to bear weight on distal weight bearing surface when casting was done. Cast was taken maintaining adequate walking base of the subject.

4. Modification procedure:

Assistive device - The positive mold was smoothed and cushioning materials were added over bony landmarks for clearance.

Extension prosthesis - Modification procedure started with the removal of extra materials followed by special modification for ischial and distal partial weight bearing design. Special addition material was done to make room for the deformed portion of the limb. The modification was completed with proper finishing of the final positive mold.

5. Draping and Lamination process:

Assistive device - The molds were draped by using suction for proper shape and trimmed according to the requirement of the subject.

Extension prosthesis - Both the sockets were laminated with suction for proper fitment. Reinforcement to the sockets to withstand the body weight was incorporated and to make the socket lighter, carbon fiber was used in the lamination. The sockets were trimmed and after successful trial, it was carried forward for alignment procedure.

6. Alignment and attachment procedure:

Assistive device - The modified suspension straps were attached.

Extension prosthesis - The mechanical knee joints were aligned to the socket with the help of a plumb- bob where the plumb line falls ½ inch anterior to shoe breast sagitally and center of the heel posteriorly. Prior to prosthetic fitting, both arm span and hand length were used to estimate the total height of the individual (H). Following the principles of body segment parameters, the knee height from floor was estimated to be 0.285 x H.

7. Training:

The subject was given training with the assistive device on and was given instructions to accommodate with it for long movements. To achieve stability and balance, she was told to stand with the prosthesis till she was stable enough and could balance walking with it. Side walking and forward walking were trained inside parallel bar till she got confidence to walk outside the parallel bar. With the help of a pair of elbow crutches, she was trained to walk on the plain surface (Figure 3).

With the assistive device and extension prosthesis, the subject was supervised every day and asked to practice for 3 to 4 hours per day with intermediary gap of 20 minutes for rest. After three weeks of practice and one year from the final fitment of extension prosthesis/knee pad, different gait parameters like step length, stride length, cadence were noted using manual gait analysis by 10 meter walk test. We used the OPUS Health Quality of Life Index component of orthotics prosthetics users survey (OPUS) to measure the quality of life of the individual before and after the rehabilitation training with extension prosthesis and knee pads. The test-retest reliability was excellent i.e. ICC=0.85 (Resnik, 2011). The higher score on OPUS health quality of life indicates a better quality of life and lower score indicates worse quality of life.

The cadence increased with the assistive device in both the follow ups i.e. after three weeks and after one year. Step length and stride length of the patient were approximately same as the patient walking without assistive device. There was reduction in all the gait parameters when the data was taken with the prosthesis on (Table 1). However, the OPUS health quality of life questionnaire score improved significantly by 44 scores (baseline 29, post rehabilitation 73) indicating significant improvement in the health quality of life of

the individual.

Discussion

The individuals with tibial hemimelia often face difficulty in walking and the abnormality in structure of the limbs can cause increased energy expenditure. Bilateral involvement makes the participation in activities of daily living very cumbersome. The individual gets restricted from participating in different sports and extracurricular activities. Amputation may be beneficial for very severely deformed lower limb but it makes the individual more dependent on the prosthesis. Reconstruction procedures may lead to negative impact on psychology and economic conditions of the individual.⁵ These problems can be resolved by proper use of medical technology i.e. prosthetic device and day to day practice with that.

Prosthetic management occupies an incomparable option for tibial hemimelia. Depending on shape of the limb, assistive devices can be designed to bring a huge change in ambulation of the patient. Advance technology can minimize the problems and increase the quality of life irrespective of other options. Selection of the prosthesis can enhance the quality of life. Conservative treatment like prosthetic management or assistive devices should be considered as the first choice of rehabilitation for tibial hemimelia.