J. of Korean Orthop. Assoc. 2004; 39: 482-8 Gait Analysis before and after Total Hip Arthroplasty in Hip Dysplasia and Osteonecrosis of the Femoral Head Su Hyun Cho, M.D., Soo Ho Lee, M.D.* , Ki Hyung Kim, M.D.*, and Jong Yoon Yu, M.D.� Department of Orthopedic Surgery, Ulsan University Hospital, College of Medicine, Ulsan University, Ulsan; Department of Orthopedic Surgery*, Department of Physical Medicine and Rehabilitation�, Asan Medical Center, College of Medicine, Ulsan University, Seoul, Korea Purpose: The aim of this study was to objectively evaluate the abnormal gait patterns and gait improve- ments after a total hip arthroplasty (THA) in patients with hip dysplasia and osteonecrosis of the femoral head (ONFH). Materials and Methods: Thirty-four patients (mean age of 43.7 years) with hip dysplasia who under- went THA were divided into the Crowe types (15 type 1, 11 type 2, 3 type 3, and 5 type 4), and gait analy- ses of these patients were performed using the Vicon 370 motion analysis system. The results of this group were compared with those of 39 age and gender matched patients with ONFH who received a THA and a group of 24 individuals with normal hips. Results: Preoperatively, the gait pattern of the hip dysplasia group did not differ significantly from that of the ONFH group with respect to the temporal gait measurement parameters, kinematics, and kinetics. However, the hip dysplasia group had a different gait pattern than the normal control group and one year after surgery, there were significant differences in the moments and powers of the hip flexors and abductors of patients with severe hip dysplasia (Crowe types 3 and 4) compared with those of the ONFH patients. Conclusion: There were less postoperative gait improvements in the patients with severe hip dysplasia than in those with ONFH who had a relatively normal anatomy. These observations might be the result of their weakened hip muscles, particularly the flexors and abductors, despite their increased range of motion after surgery. Perioperative muscle strengthening exercises may be needed to improve gait pat- terns in patients with hip dysplasia. Key Words: Hip dysplasia, Osteonecrosis of the femoral head, Total hip Arthroplasty, Gait analysis Hip dysplasia, which originally meant a developmental tis of the hip resulting from hip dysplasia, the treatment of dislocation or subluxation of the hip, also includes other choice is total hip arthroplasty (THA). However, patients causes of dislocation or subluxation resulting from the sequela with THA in such cases are generally less satisfied with their of pediatric hip disorders. These may include Legg-Calve- treatment than patients who had THA for other hip diseases. Perthes disease, slipped capital femoral epiphysis, or trau- This higher level of dissatisfaction is due to residual limping ma. Persistent dislocation or subluxation of the hip may lead and abnormal proprioceptive sensations resulting from the to hypoplasia of the acetabulum and femur, which manifest various soft tissue abnormalities. Nonetheless, there is a pauci- as a decreased acetabular coverage of the femoral head, a leg ty of objective and quantitative data on the gait after a THA length discrepancy, soft tissue contracture and atrophy of the in these cases. Therefore, this study compared a group with muscles, particularly the hip abductors, which may lead to hip dysplasia with two groups of patients with respect to their osteoarthritis of the hip. In the case of advanced osteoarthri- gait patterns after THA: one group with normal hips and the other group with osteonecrosis of the femoral head (ONFH). Address reprint requests to Soo Ho Lee, M.D. Department of Orthopedic Surgery, Asan Medical Center, MATERIALS AND METHODS 388-1 Pungnap-dong, Songpa-gu, Seoul 138-736, Korea 1. Materials Tel: +82.2-3010-3530, Fax: +82.2-488-7877 E-mail: [email protected] From June 1996 to January 2002, 132 patients with hip 482 Gait Analysis before and after Total Hip Arthroplasty in Hip Dysplasia and Osteonecrosis of the Femoral Head 483 dysplasia received a THA, 34 of whom (20 males and 14 were those for the temporal gait measurements, kinematics females) with a mean age of 43.7 years (31-62 years) were and kinetics. enrolled in this study. All surgical procedures were performed with an insertion of the acetabular and femoral components 1) Static method without cement. Eighteen patients had developmental dys- After attaching the indicators on the major landmarks of plasia of the hip and 16 had Legg-Calve-Perthes disease. the body, such as the pelvis or knee, the 3 dimensional posi- There was an average leg length discrepancy of 19.7 mm tion of the indicators was identified graphically on a com- (16.7-22.5 mm ) preoperatively and 8.1 mm (5.3-9.2 mm) puter monitor. one year after surgery. According to the Crowe classification3) for hip dysplasia, there were 15 type-1 cases, 11 type-2 cases, 2) Dynamic method 3 type-3 cases, and 5 type-4 cases. The first control group After removing both calcaneal indicators, the patients were consisted of 24 age and gender matched normal healthy permitted to walk a distance of 10 m approximately 10 times adults (12 males and 12 females), with a median age of 44.1 back and forth in order to select the most natural gait for years (23-67 years). The second control group consisted of analysis. The analog data obtained from the motion analy- 39 age and gender matched patients (23 males and 16 fe- sis system was processed using a Vicon clinical manager soft- males) with a median age of 50.5 years (26-74 years) receiv- ware program to yield 3 dimensional digital data, which was ing a THA for ONFH. transformed into 3 dimensional sagittal, coronal and trans- Two surgical approaches were used: the posterolateral ap- verse joint motions on the computer screen. proaches were used in 56 hips and the direct lateral approach- es with an osteotomy of the greater trochanter was used in 3) Parameters of analysis 17 hip dysplasia cases. Three prosthetic designs were used: The temporal kinematic and kinetic parameters of ankle, S-ROM components (DePuy, Warsaw, USA) were implant- knee and hip motion along with the selected data for hip ed in 15 hips; Biocontact components (Aesclaup, Germany) motion only were analyzed. The temporal gait parameters were used in 30 hips; C2 component (Lima-Lto, Italy) was measured were the walking velocity, cadence, walking cycle used in 28 hips. The gait analysis was performed before duration, stride length, single support phase and double sup- surgery and 6 months and 1 year after surgery. port phase. The kinematic parameters for the pelvis were translation, obliquity and rotation in terms of the coronal, 2. Gait analysis sagittal and transverse planes, respectively, whereas those for Gait analysis was performed using a 3-dimensional com- the hip joint were flexion, adduction and rotation in terms of puterized Vicon 370 motion analysis system (Oxford Met- the coronal, sagittal and transverse planes, respectively. The ric, Oxford, England) (Fig. 1). The parameters measured maximum and minimum values of each were measured. The kinetic parameters analyzed were the hip joint moment and joint power. The hip joint moment comprised of 8 items in the sagittal, coronal and transverse planes: the maximum extension moment in the loading response phase, the maxi- mum flexion moment in the terminal stance phase, the maxi- mum abduction moment in the early single support phase, the maximum abduction moment in the middle single sup- port phase, the maximum abduction moment in late single support phase, the maximum external rotation moment in the early single support phase and the maximum internal rotation moment in the late single support phase. The hip Fig. 1. A patient is undergoing gait examination with indicators joint power consisted of 11 items: the maximum and mini- attached. mum values of the total hip joint muscle strength, the maxi- 484 Su Hyun Cho∙Soo Ho Lee∙Ki Hyung Kim, et al. mum generation of the hip joint strength in the sagittal postoperative results of the hip dysplasia group and an inde- plane in the loading response phase, the maximum absorp- pendent t-test to compare the results of the hip dysplasia tion of the hip joint strength in the sagittal plane in the ter- and ONFH groups. The Mann-Whitney test was used to minal stance phase, the maximum generation of the hip joint compare results of the normal and hip dysplasia group, as strength in the sagittal plane in the preswing phase, the maxi- well as to compare the results of the patients with Crowe mum absorption of the hip joint strength in the sagittal plane types 3 and 4 in the hip dysplasia group and ONFH group. in the terminal swing phase, the maximum generation of hip joint strength in the coronal plane in the loading response RESULTS phase, the maximum generation of the hip joint strength 1. Preoperative comparison of the hip dysplasia group in the coronal plane in the midstance phase, the maximum with the two other groups generation of the hip joint strength in the coronal plane in All the temporal gait measurements were significantly the terminal stance phase, the maximum generation of the poorer preoperatively in the hip dysplasia group than in the hip joint strength in the transverse plane in the midstance normal control group (p<0.05) (Table 1). The kinematic phase, and the maximum generation of the hip joint strength indices showed that the maximum anterior obliquity of the in the transverse plane in the terminal stance phase. pelvis had increased to 22.5° in the hip dysplasia group com- pared with 15.9° in the normal control group.