Gait Analysis Before and After Total Hip Arthroplasty in Hip Dysplasia and Osteonecrosis of the Femoral Head

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 improvements 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 analyses 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 patterns 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 approaches 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 maximum flexion moment in the terminal stance phase, the maximum abduction moment in the early single support phase, the maximum abduction moment in the middle single support 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 compared with 15.9° in the normal control group. The mini- 3. Statistical analysis mum hip joint flexion and medial displacement were also This study used a paired t-test to compare the pre- and increased in the hip dysplasia group compared to the nor-

Table 1. Temporal gait parameters of hip dysplasia and ONFH

Hip dysplasia ONFH Control Preop Postop 6M Postop 12M Preop Postop 6M Postop 12M Cadence (steps/min) 85.73±12* 95.70±14.2 88.91±7.9 93.24±14 97.98±15.1 102.32±11.5 115±10.8 Speed (cm/sec) 0.67±0.7* 0.86±0.9� 0.92±0.5 0.69±0.1 0.72±0.5� 0.88±0.6�� 1.16±0.3 Stride length (cm) 0.84±0.5 0.96±0.4� 0.95±0.3 0.85±0.2 0.95±0.6� 1.02±0.6� 1.27±0.19 Step time (sec) 0.69±0.7* 0.78±0.3 0.83±0.2 0.58±0.2 0.63±0.4� 0.58±0.12�� 0.58±0.05 Single support (% cycle) 30.12±9.1* 33.41±5.2� 31.72±4.2� 31.33±9.0 37.1±6.1� 37.24±5.0�� 42.22±2.9 Double support (% cycle) 29.39±16.8* 29.58±9.2 27.75±6.1 33.98±17.4 27.4±8.9� 25.16±5.8�� 22.68±4.2

*p<0.05 between control & hip dysplasia at pre OP, ‖p<0.05 between hip dysplasia & ONFH at pre OP, �p<0.05 between Preop and Postop 12M by Paired t-test, �p<0.05 between hip dysplasia & ONFH at post OP 12Ms, �p<0.05 between Preop and Postop 6M by Paired t-test, Val- ues are mean±standard deviation. Table 2. Kinematics of pelvis and hip in hip dysplasia and ONFH

Hip dysplasia ONFH Control Preop Postop 6M Postop 12M Preop Postop 6M Postop 12M Anterior Maximum 22.5±8.6* 19.1±6.4� 20.9±6.3� 21.6±7.4‖ 19.4±6.8� 20.7±5.9� 15.9±6.2 Pelvic tilt Minimum 14.3±7.8 14.3±7.2 10.3±6.4 14.8±7.1 15.2±6.6 16.1±6.2 12.2±6.3 P. upward Maximum 3.2±8.7 5.5±9.0� 2.9±5.6 2.9±9.5 4.2±10.0� 2.9±6.1 4.9±3.2 obliquity Minimum -3.9±9.7 -5.6±9.3 -5.6±5.9 -3.6±7.6 -3.2±9.1 -4.3±4.8 -4.4±3.4 P. internal Maximum 6.1±2.8 11.9±5.5� 9.5±2.4 4.5±2.6‖ 3.4±4.5 4.4±3.6 3.86±3.5 rotation Minimum -4.2±27.7 -6.4±24.3 -3.5±15.4 -4.5±26.6 -2.6±22.9� -2.9±16.3� -6.21±3.2 Hip flexion maximum 35.92±11.6 35.5±9.0 38.9±8.2 34.9±13.8 38.4±8.1� 39.6±7.1� 38.2±7.2 minimum 13.63±13.3 *6.9±10.1� 5.3±10.1 11.2±12.5 -1.43±8.9 5.7±9.0 -8.2±9.2 Hip adduction maximum 4.8±8.4 4.4±4.1 3.7±4.1� 4.1±5.8 6.4±3.9� 6.1±3.7 10.7±2.9 minimum -3.4±8.5 -4.7±4.4 -4.4±4.8 -3.3±4.8 -3.6±5.1 -3.9±3.9 -2.2±3.9 Hip internal maximum 20.7±16.2 15.9±12.3 11.9±13.0 16.6±15.8 13.2±12.0 13.6±9.9 11.5±12.1 rotation minimum -5.5±14.5* -9.6±11.7 -9.4±13.2 -9.3±16.4 -7.6±11.9 -10.6±12.1 -16.8±13.9

P., pelvic; *p<0.05 between control & hip dysplasia at pre OP, ‖p<0.05 between hip dysplasia & ONFH at pre OP, �p<0.05 between Preop and Postop 12M by Paired t-test, �p<0.05 between hip dysplasia & ONFH at post OP 12Ms, �p<0.05 between Preop and Postop 6M by Paired t-test, Values are mean±standard deviation. Gait Analysis before and after Total Hip Arthroplasty in Hip Dysplasia and Osteonecrosis of the Femoral Head 485

Table 3. Kinetics of hip (moment) in hip dysplasia and ONFH

Hip dysplasia ONFH Control Preop Postop 6M Postop 12M Preop Postop 6M Postop 12M HMFlex 1. 0.45±0.24* 0.59±0.25 0.42±0.24 0.37±0.20 0.51±0.27� 0.54±0.26�� 0.68±0.3 2. -0.31±0.21* -0.42±0.21 -0.46±0.26 -0.29±0.21 -0.42±0.25� -0.45±0.26� -0.52±0.31 3. 0.31±0.16* 0.43±0.21� 0.32±0.26 0.25±0.19 0.35±0.20 0.40±0.25�� 0.47±0.27 HMAbd 1. 0.63±0.24 0.79±0.21 0.71±0.27 0.56±0.18 0.72±0.21� 0.69±0.24 0.75±0.19 2. 0.42±0.23* 0.53±0.21� 0.42±0.25 0.37±0.19 0.55±0.20� 0.52±0.22� 0.65±0.22 3. 0.62±0.22 0.73±0.19 0.62±0.27 0.59±0.19 0.69±0.21� 0.70±0.23� 0.71±0.14 HMRot 1. -0.04±0.07* -0.04±0.08 -0.04±0.08 -0.02±0.08 -0.05±0.10� -0.04±0.10� -0.08±0.12 2. 0.05±0.08* 0.09±0.05 0.05±0.08 0.06±0.07 0.11±0.10� 0.09±0.10 0.14±0.11

HMFlex 1: Maximal hip extensor moment in loading response, 2: in terminal stance response, 3: in terminal swing. HMAbd 1: Maximal hip abduction moment in early single limb support, 2: in mid single limb support, 3: in late single limb support. HMRot 1: Maxiaml hip external rotation moment in early single limb support, 2: in late single limb support. *p<0.05 between control & hip dysplasia at pre OP, ‖p<0.05 between hip dysplasia & ONFH at pre OP, �p<0.05 between Preop and Postop 12M by Paired t-test, �p<0.05 between hip dysplasia & ONFH at post OP 12 Ms, �p<0.05 between Preop and Postop 6M by Paired t-test. Val- ues are mean±standard deviation. Table 4. Kinetics of hip (power) in hip dysplasia and ONFH

Hip dysplasia ONFH Control Preop Postop 6M Postop 12M Preop Postop 6M Postop 12M HPTotal max 0.47±0.41 0.74±0.35� 0.62±0.48 0.43±0.60 0.53±0.41 0.83±0.52� �1.09±0.25 HPFlex 1. 0.83±0.27* 0.68±0.31 0.52±0.24 0.73±0.38 0.61±0.46 0.59±0.48� 0.88±0.29 2. -0.17±0.15* -0.24±0.19 -0.57±0.31 -0.17±0.41 -0.33±0.33 -0.26±0.34 -0.36±0.19 3. 0.43±0.37* 0.52±0.44 0.54±0.47 0.32±0.59 0.61±0.38� 0.73±0.51�� 0.84±0.30 4. -0.17±0.16* -0.23±0.19 -0.17±0.21 -0.13±0.25 -0.24±0.27� -0.21±0.30� -0.19±0.18 HPAbd 1. -0.10±0.17* -0.31±0.24� -0.25±0.24 -0.16±0.22 -0.27±0.28� -0.19±0.30� -0.36±0.16 2. 0.15±0.24* 0.18±0.15 0.15±0.31 0.10±0.34 0.11±0.25 0.16±0.29� 0.25±0.25 3. 0.21±0.16* 0.26±0.14 0.27±0.22 0.18±0.22 0.31±0.19� 0.33±0.20� 0.43±0.20 HPTotal: Total hip power, HPFlex 1: Maximal hip power generation in loading response on sagittal plane, 2: in terminal stance, 3: in preswing, 4: in terminal swing phase. HPAbd 1: Maximal hip power absorption in loading response on coronal plane, 2: in midstance, 3: in terminal stance. *p<0.05 between control & hip dysplasia at pre OP, ‖p<0.05 between hip dysplasia & ONFH at pre OP, �p<0.05 between Preop and Postop 12M by Paired t-test, �p<0.05 between hip dysplasia & ONFH at post OP 12Ms, �p<0.05 between Preop and Postop 6M by Paired t-test. Val- ues are mean±standard deviation. mal control group (Table 2). The kinetic indices showed significant differences were observed in the angles of the that the hip joint moments and powers were significantly pelvis and hip joint, although an overall improvement was different in the two groups (Table 3, 4). When the patients observed. Only the lateral displacement and internal rota- with hip dysplasia were compared to those with ONFH, tion of the pelvis had improved by 6 months after surgery, the gait pattern was generally poorer in the former group, but declined thereafter (Table 2). Similarly, with hip joint but only the anterior obliquity and transverse rotation of flexion and abduction moment as well as the total hip joint the pelvis was significantly different (Table 1-4). flexion and abduction power improved significantly 6 months after surgery, but had decreased by 1 year. The other param- 2. Preoperative and postoperative comparison of the eters of the hip joint moment and power did not differ sig- hip dysplasia group nificantly by 6 months and 1 year after surgery compared Six months after the THA in patients with hip dysplsia, with the preoperative values (Table 3, 4). the walking velocity and stride length improved significantly, but declined to preoperative levels after 1 year. The sin- 3. One year postoperative comparison of hip dysplasia gle support phase parameters increased significantly after group and ONFH group surgery compared with the preoperative levels (Table 1). No All the temporal gait measurements other than the stride 486 Su Hyun Cho∙Soo Ho Lee∙Ki Hyung Kim, et al.

Table 5. Kinetics of hip (moment) in hip dysplasia, ONFH, Table 6. Kinetics of hip (power) in hip dysplasia, ONFH, and and Crowe 3, 4 Crowe 3, 4

Hip dysplasia Crowe 3, 4 ONFH Hip dysplasia Crowe 3, 4 ONFH HMFlex 1. 0.51±0.24 0.42±0.31 0.54±0.26 HPTotal max 0.64±0.43 0.58±0.41* 0.83±0.52 2. -0.42±0.31 -0.41±0.25 -0.45±0.26 HPFlex 1. 0.59±0.35 0.37±0.28 0.59±0.48 3. 0.35±0.28 0.33±0.41 0.40±0.25 2. -0.66±0.29 -0.24±0.19 -0.26±0.34 HMAbd 1. 0.64±0.20 0.69±0.14* 0.69±0.24 3. 0.64±0.48 0.39±0.36* 0.73±0.51 2. 0.42±0.24 0.44±0.22* 0.52±0.22 4. -0.22±0.19 -0.18±0.11 -0.21±0.30 3. 0.61±0.24 0.64±0.28* 0.70±0.23 HPAbd 1. -0.21±0.26 -0.12±0.18 -0.19±0.30 HMRot 1. 0.03±0.12 -0.04±0.07* -0.04±0.10 2. 0.13±0.27 0.21±0.25 0.16±0.29 2. 0.07±0.07 0.07±0.14* 0.09±0.10 3. 0.27±0.25 0.24±0.18* 0.33±0.20

HMFlex 1: Maximal hip extensor moment in loading response, 2: in HPTotal: Total hip power, HPFlex 1: Maximal hip power generation terminal stance response, 3: in terminal swing. HMAbd 1: Maximal in loading response on sagittal plane, 2: in terminal stance, 3: in hip abduction moment in early single limb support, 2: in mid single preswing, 4: in terminal swing phase. HPAbd 1: Maximal hip power limb support, 3: in late single limb support. HMRot 1: Maxiaml hip absorption in loading response on coronal plane, 2: in midstance, external rotation moment in early single limb support, 2: in late sin- 3: in terminal stance. gle limb support. *p<0.05 between Crowe 3, 4 & ONFH at post OP 12Ms. Values are *p<0.05 between Crowe 3, 4 & ONFH at post OP 12Ms. Values are mean±standard deviation mean±standard deviation. tions. Therefore they tend to lack objectivity. Moreover, there length were significantly worse in the patients with hip dys- are significant differences between how the patients and phy- plasia compared to those with ONFH. Similarly, the maxi- sicians evaluate these scores. This study attempted to solve mum internal rotation of the hip joint and hip joint flexion this problem by using standard gait analysis, which objec- moment and power were significantly worse in the patients tively evaluated the function rather than pain. By evaluat- with hip dysplasia compared to those with ONFH (Table ing the coronal, sagittal and transverse aspects of the patient’s 1-4). gait simultaneously, 3-D gait analysis can offer objective, quantitative data while excluding the subjective evaluations 4. One year postoperative comparison of Crowe types by the examiners. 3 and 4 in the hip dysplasia group and ONFH group The gait analysis in patients with degenerative arthritis of When Crowe type 3 and 4 patients with the hip dyspla- the hip or advanced ONFH showed alterations in the tem- sia were compared with the patients with ONFH after sur- poral gait measurements, including the decreased walking gery, the hip joint moment was significantly worse in the velocity and single support phase and the increased double former group, with the exception of the maximum exten- support phase7). In addition, the characteristic of painful gait sion moment of the hip joint at the end of the stance phase. was an increased anterior displacement of the pelvis: 4° in The power was also significantly different including the max- normal controls and 11° in those with hip pain7). It was also imum hip joint power, the hip joint flexion power before found in our study that all the temporal gait measurement the swing phase, and hip joint abduction power at the end indices in the patients with hip dysplasia were abnormally of the stance phase (Table 5, 6). different from those of the normal controls preoperatively and that the anterior obliquity of the pelvis was increased DISCUSSION in the patients with hip dysplasia. A similar pattern in the A THA is frequently performed in patients with hip dys- gait analyses was observed in the ONFH patients compared plasia as well as those with ONFH. Postoperatively, the to those with hip dysplasia preoperatively, suggesting that pathological gait pattern persists more in patients with hip the abnormal gait in patients with hip dysplasia was prob- dysplasia, and also subsides slowly over a long period of time. ably from the result of pain, as observed in ONFH patients. Clinically, the Harris hip score4) and the Western Ontario The gait pattern has usually been reported to improve sig- McMaster University (WOMAC) Osteoarthritis index1) have nificantly after a THA. However, the period of this improve- been used to evaluate patients after a THA. However, these ment has been reported to vary: from 4 to 8 months2), 0 to tools are based on patient interviews and physical examina- 6 months9), and as rapid as 0 to 3 months6). The latter group Gait Analysis before and after Total Hip Arthroplasty in Hip Dysplasia and Osteonecrosis of the Femoral Head 487

reported that the muscle torque increased up to 3 months range of motion would improve the kinematic indices posto- postoperatively, but was stationary from 3 to 6 months, sug- peratively, but an incomplete recovery of the muscle strength gesting that the initial increase was due to decreased pain would not significantly improve the kinetic indices. while the subsequent plateau was due to preoperative dis- The limitations of this study include the short follow-up use atrophy and an unavoidable abduction muscle injury period and the small number of patients with severe hip dys- during surgery. This study showed that there was little gait plasia (Crowe types 3 and 4). Nevertheless, these results sug- improvement from 6 months to 1 year after surgery, which gest that a worsening of the various gait parameters between might be due to muscle weakening. The gait improvement 6 months and 1 year after THA is probably due to muscle was less prominent in those patients with hip dysplasia com- weakening. However, it is also expected that the gait will pared to those with ONFH improve further with sufficiently rehabilitated muscles, and Susack et al.8) reported continued waddling gait in a 15- that perioperative continuous muscle strengthening exer- year-old girl with bilateral developmental dysplasia of the cises will aid in the postoperative gait improvement. hip due to abductor muscle atrophy after receiving a THA. This suggests that the postoperative gait will be poorer in CONCLUSION patients with hip dysplasias than in those with ONFH, as An analysis of 47 patients with hip dysplasia and 39 pa- a result of the muscle atrophy and soft tissue contracture in tients with ONFH, before surgery as well as 6 months and the former. The present study showed that, 1 year after sur- 1 year after THA, showed little improvement in the kinet- gery, the single support phase of the temporal gait measure- ic parameters in the former group. These findings suggest ment indices and the various kinematic indices, including that muscle weakening around the hip joint may cause resid- the maximum anterior obliquity of the pelvis and hip joint ual limping despite the improvement in pain. Therefore, it flexion, abduction, and internal rotation, improved signifi- may be helpful to encourage patients with hip dysplasia to cantly in those patients with hip dysplasia, but the kinetic strengthen their hip flexor and abductor muscles after sur- factors that are indicative of muscle strength showed little gery. A longer follow-up of these patients is expected to show improvement, suggesting that the persistence of postoper- the benefits of muscle strengthening exercises. ative gait abnormalities was due to muscle weakening in the hip joint. Lai et al. reported that after a gait analysis over an REFERENCES average of 58 months after THA in 22 Crowe type 4 patients 1. Bellamy N, Buchanan WW, Goldsmith CH, Campbell J and with hip dysplasia, there were significant increases in the Stitt LW: Validation study of WOMAC: a health status instru- temporal gait measurements including the walking veloci- ment for measuring clinically important patient relevant outcomes ty and single support phase, the kinematic indices includ- to antirheumatic drug therapy in patients with osteoarthritis of the ing the anterior displacement of the pelvis, and the kinetic hip or knee. J Rheumatol, 15: 1833-1840, 1988. indices compared to the normal controls5). However this 2. Berman AT, Quinn RH and Zarro VJ: Quantitative gait analy- study did not show that the postoperative kinetic indices sis in unilateral and bilateral total hip replacements. Arch Phys Med had improved significantly in patients with hip dysplasia, Rehabil, 72: 190-194, 1991. suggesting that a follow-up period longer than 1 year is nec- 3. Crowe JF, Mani VJ and Ranawat CS: Total hip replacement in essary for pertinent results. This study compared the Crowe congenital dislocation and dysplasia of the hip. J Bone Joint Surg, 61- type 3 and 4 patients in the hip dysplasia group with those A: 15-23, 1979. with ONFH, and found that all the kinetic indices, which 4. Harris WH: Traumatic arthritis of the hip after dislocation and indirectly reflected the muscle strength, differed significant- acetabular fractures: treatment by mold arthroplasty. An end-study ly. In contrast, amongst the kinematic indices, which pri- result using a new method of result evaluation. J Bone Joint Surg, marily reflect the range of motion of joint, only the anteri- 51-A: 737-755, 1969. or displacement and transverse rotation of the pelvis differed 5. Lai KA, Lin CJ, Jou IM and Su FC: Gait analysis after total hip significantly. Therefore we thought that regardless of the arthroplasty with leg-length equalization in women with unilateral degree of hip dysplasia, decreased pain and increased joint congenital complete dislocation of the hip-comparison with untreated 488 Su Hyun Cho∙Soo Ho Lee∙Ki Hyung Kim, et al.

patients. J Orthop Res, 19: 1147-1152, 2001. lar necrosis. J Bone Joint Surg, 53-A: 259-274, 1971. 6. Murray MP, Brewer BJ and Zuege RC: Kinegiologic measure- 8. Susak Z, Katz K and Seliktar R: Persistence of waddling gait ments of functional performance before and after McKee-Farrar total after total hip replacement for congenital dislocation of the hip. Scand hip replacement. A study of thirty patients with rheumatoid arthri- J Rehabil Med, 12: 113-114, 1980. tis, osteoarthritis, or avascular necrosis of the femoral head. J Bone 9. Wall JC, Ashburn A and Klenerman L: Gait analysis in the Joint Surg, 54-A: 237-256, 1972. assessment of functional performance before and after total hip re- 7. Murray MP, Gore DR and Clarkson BH: Walking pattern of placement. J Biomech Eng, 3: 121-127, 1981. patients with unilateral hip pain due to osteoarthritis and avascu-

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조수현ㆍ이수호*ㆍ김기형*ㆍ유종윤�

울산대학교 의과대학 울산대학교병원 정형외과학교실, 서울아산병원 정형외과학교실*, 재활의학과�

목적: 고관절 이형성증 환자의 고관절 전치환술 후 기능적 호전을 객관적이고 정량적으로 평가하고자 3차원 동작 분석기 를 이용하여 수술 전, 후의 보행 변화를 관찰하고 대퇴골두 골괴사 환자와 보행 호전정도를 비교하였다. 대상 및 방법: 1996년 6월부터 2002년 1월까지 본원에서 고관절 이형성증으로 수술한 34예를 대상으로 하였으며, 평균 연 령은 43.7세였고, Crowe 1형이 15예, 2형이 11예, 3형이 3예, 4형이 5예이었고, 보행분석은 Vicon 370 motion analysis system을 사용하였다. 비교군은 나이, 성별 등에서 조화되는 대퇴골두 골괴사 환자 39예와 24예의 정상 성인군으로 하였다. 결과:수술 전 고관절 이형성증 환자의 보행은 정상에 비해 보행 선형요소, 운동형상학 및 운동학적 요소 전부분에서 유의 한 차이가 있었으나 대퇴골두 골괴사군과는 유의한 차이가 없었다. 하지만 수술 1년 후 고관절 이형성증 환자군 중 Crowe 3, 4형은 대퇴골두 골괴사군에 비해 고관절 굴곡력과 외전근력에서 유의하게 불량한 결과를 보였다(p<0.05). 결론:3차원 보행 분석상 고관절 이형성증은 고관절 전치환술 후에도 대퇴골두 골괴사 환자에 비해 보행 양상이 불량하였 으며, 이는 주로 고관절 근력, 특히 굴곡근과 외전근의 약화에 의한 것임을 알 수 있었다. 따라서 고관절 이형성증 환자의 경우 수술 후 지속적인 고관절 굴곡근과 외전근의 근력 강화 운동이 보행의 호전에 도움이 되리라 생각된다. 색인 단어: 고관절 이형성증, 대퇴골두 골괴사, 고관절 전치환술, 보행분석