Comparing dome high tibial osteotomy for patients more than sixty years old with patients less than sixty years old

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1 Asian Biomedicine Vol. 2 No. 5 October 2008; Original article Comparing dome high tibial osteotomy for patients more than sixty years old with patients less than sixty years old Prakit Tienboon a, Surapon Atiprayoon b a Department of Orthopedics, Faculty of Medicine, Chulalongkorn University, Bangkok 10330; b Department of Orthopedic, Surgery Queen Savang Vadhana Memorial Hospital, Chonburi 20000, Thailand Background: Although high tibial osteotomy for varus deformity in younger patients has been proven effective and proper for the treatment of painful osteoarthritis, the role of dome high tibial osteotomy for osteoarthritis knee in patients older than 60 years old in good selected cases is still the proper choice of surgery. Objective: To study the outcome of high tibial osteotomy for osteoarthritis knee in patients older than 60 years. Methods: We evaluated the results in eighty-eight patients (one hundred and ten knees) that had been treated by dome high tibial osteotomy and fixed with Charnley s external fixator for varus deformity and osteoarthritis of the medial compartment. In the retrospective study, patients were divided into two groups. In the first group, there were 50 knees of 39 patients under 60 years. The second group was 60 knees of 49 patients over 60 years. The results were evaluated using the Knee Society score, the rating system described by Coventry, anatomical femorotibial axis, survivorship analysis with total knee arthroplasty as the end point and complications. Results: In the first group whose ages were under 60, the mean preoperative and postoperative Knee Society scores were 62 and 85.98, respectively (p<0.05). The mean preoperative anatomical femorotibial axis had improved from varus 4.39 degrees to valgus 6.48 degrees. Survivorship analysis with total knee arthroplasty as the end point was 100% at five years and 78.13±11.28% at ten years. In the second group (over 60), the mean preoperative and postoperative Knee Society scores were and 88.20, respectively (p<0.05). The mean preoperative anatomical femorotibial axis improved from varus 5.03 degrees to valgus 7.56 degrees. The survivorship analysis with total knee arthroplasty as the end point was 98.3±1.65% at five years and 83.21±9.94% at 10 years. Conclusion: Dome high tibial osteotomy using Charnley s external fixator was as effective a procedure for treatment of medial osteoarthritis in patients over 60 years as in patients under 60 years. We highly recommend dome high tibial osteotomy with minimal invasive technique and fixed with Charnley s external fixator for patients both younger and older than 60 years in good selected cases who wish to continue an active lifestyle. Keywords: High tibial osteotomy, knee, osteoarthritis. In 1958, Jackson [1] first reported the use of tibial osteotomy in the treatment of pain due to osteoarthritis of the knee joint. High tibial osteotomy was a modality in the management of unicompartmental osteoarthritis which is based on the principle of redistribution of body weight from the arthritic medial femorotibial compartment to the healthy lateral one to relieve symptoms and slow Correspondence to: Prakit Tienboon MD, Department of Orthopedics, Faculty of Medicine, Chulalongkorn University, Bangkok 10330, Thailand. drprakit@hotmail.com disease progression. Pauwels [2] showed that a previously narrowed joint space will widen postoperatively and both subchondral cysts and sclerosis will regress if stress in the affected compartment is reduced sufficiently. In Kroner s study [3] to determine the influence of high tibial osteotomy on subchondral bone marrow edema in medial osteoarthritis of the varus knee, all knees with postoperative valgus alignment showed reduced edema. In contrast, bone marrow edema increased or remained unchanged in 40 percent of knees with postoperative neutral or varus alignment. A longer

2 382 P. Tienboon, S. Atiprayoon postoperative recovery period with less pain relief after rehabilitation was expected after osteotomy. These disadvantages had to be balanced against the possible catastrophic complications of infection or prosthetic failure with arthroplasty in young and active patients. The prevalence of realignment osteotomy had steadily declined because of the success of total knee replacement (TKR). Despite this rather significant decline, osteotomy remained a proper treatment option in carefully selected patients with medial knee arthritis. Coventry [4] concluded that a patient with early symptomatic unicompartmental osteoarthritis was an ideal candidate for osteotomy. The goal of the tibial osteotomy was to correct the mechanical axis deviation of the lower limb and to hold it at the desired position. Subsequently, different osteotomy techniques were published such as closed wedge osteotomy, open wedge osteotomy, dome osteotomy and achieving a gradual correction with an external fixator [5]. The ideal candidate for osteotomy was a thin active individual in the fifth or sixth decade of life who had localized, activity-related, unicompartmental knee pain [6]. The purpose of this study was to assess the long-term results, complications and their solutions of dome high tibial osteotomy for the treatment of medial osteoarthritis of the knee even in patients more than sixty years old compared to the treatment in patients less than sixty years old. Materials and methods One hundred and ten consecutive dome high tibial osteotomies (HTO) were performed in 88 patients (22 of whom had a bilateral procedure) between 1997 through 2003 by two surgeons. In the retrospective study, patients were divided into two groups. In the first group, there were 50 knees from 39 patients under 60 years old (mean age of 54). The second group was 60 knees from 49 patients over 60 years old (mean age of 66). For the first group, patients were under 60, the number of men to women was 1/38 and body mass index in average was For the second group, patients were older than 60, the number of men to women was 9/40 and body mass index in average was In patients younger than 60, the stage of gonarthrosis in Ahlback classifications [7] I were 18%, Ahlback II were 72% and Ahlback III were 10%. Comparing to the other group who were more than 60 years old, Ahlback I were 40%, Ahlback II were 50% and Ahlback III were 10% (Table 1). All knees had degenerative joint disease involving the medial compartment due to varum deformity. The indications for dome high tibial osteostomy were pain in the medial side of the knee that limited activities and reduced the quality of life, varus malalignment, and a desire to remain active. The amount of medial joint space remaining was considered irrelevant if these three conditions were met. Some patients had a considerable amount of medial cartilage remaining and some had no medial joint space remaining as seen on weightbearing anteroposterior radiographs. Patients with inflammatory arthritis, restricted knee motion (exceeding 20 degrees of extension deficit and less than 90 degrees of knee flexion), involvement of the medial and lateral compartment of the femorotibial joint, and instable knee were excluded from this study. Mild or moderate involvement of the patellofemoral joint was not a contraindication to this procedure. Table 1. Demographic data of patients. Variables Age<60 years Age>60 years (n=50) (n=60) Number of patients Age at time of operation (±4.35) (±5.75) Gender Male 1 9 Female Body mass index (±3.64) (±2.38) Ahlback stage (number of patients) I 9 (18.0%) 24 (40.0%) II 36 (72.0%) 30 (50.0%) III 5 (10.0%) 6 (10.0%)

3 Vol. 2 No. 5 October 2008 High tibial osteotomy for patients under and over 60 years 383 The Ahlback radiographic evaluation scale was used to determine the involvement of each tibiofemoral compartment. All of the patients charts were reviewed retrospectively to determine demographic characteristics, previous operative procedures and the preoperative diagnosis. The Knee Society score (Insall Modification-1993) [8] and the rating system described by Coventry [4] were used to evaluate preoperative and last follow-up status of the patients. A statistical analysis with the Kaplan-Meier [9] method with Hall-Wellner [10] confidence intervals was performed to determine the survival curve. The radiographs included a standard weightbearing anteroposterior view; a lateral view with 30 degrees of knee flexion and axial view with 30 degrees of knee flexion were made preoperatively and postoperatively. All radiographs were reviewed by one of us (S.A.). Femorotibial anatomical alignment was calculated. Surgical technique All patients were placed in the supine position on the operating table. A pneumatic tourniquet was used on patients without venous problems of the lower extremity. At first, the fibular osteotomy was performed at the middle-distal 1/3 junction with a separate lateral small skin incision. For dome high tibial osteotomy, a longitudinal incision 2.5 cm long was begun just proximally over the tibial tubercle. With a minimal invasive surgical technique, the aponeurosis was of limited split on both sides of the patella tendon only for the osteotomy site. Holes were made by a small air-powerd drill to delineate a curve around and above the tibial tuberosity. With a thin osteotome, the bone was then divided along the curved line formed by the air drill holes. The upper 4 mm Steinmann pin was passed from the lateral to the medial side. The osteotomy was gently broken by forceful manual valgus deviation and an anterior shift of 0.5 cm might be done. Then the lower 4 mm. Steinmann pin was passed from the lateral side also while the assistant maintained the alignment of the osteotomy. Charnley s external fixator was assembled to the Steinmann pins. The Charnley clamps were compressed on the lateral side first and then on the medial side until the alignment of the limb would touch the medial side of medial malleolus, its anatomical axis approximately 6 degrees (Fig. 1). To ensure that adequate correction had been achieved, the anatomical axis was radiologically checked. The proper alignment was between 6 degrees to 10 degrees. If the tibiofemoral axis was more or less than the proper degree, we could adjust Fig. 1 The operation aims at overcorrecting the deformity and at displacing forward the tibial tuberosity.

4 384 P. Tienboon, S. Atiprayoon the alignment again postoperatively. Postoperative treatment consisted of toe-touch weight-bearing with a walker on the second postoperative day and partial weight bearing around 50 percent on the third week. After six weeks, if the patient could walk without a gait aid and X-ray showed evidence of healing, the Steinmann pins were removed. Results In the less than 60 years old group, preoperative femorotibial angle was improved from varus 4.39 ο to valgus 6.48 ο. A mean of degrees valgus osteotomy was obtained. The average preoperative Knee Society score improved from 62 points to points at the last follow-up. The differences of the scores were found significant (p<0.05). According to the rating system described by Coventry, the outcome was good in 43 knees (86%) (Fig. 2), fair in 4 knees (8%) and poor in 3 knees (6%) at the end of the mean follow-up of 7.68 years. In the other group in which ages were more than 60 years, preoperative femorotibial angle improved from varus 5.03 ο to valgus 7.56 ο. A mean of degrees valgus osteotomy was obtained. The average preoperative Knee Society score improved from points to points at the last follow-up. The differences of the scores were found to be significant (p<0.05). According to the rating system described by Coventry, the outcome was good in 53 knees (88.3%) (Fig. 3), fair in 4 knees (6.7%) and poor in 3 knees (5.0%) at the end of the mean A B C Fig. 2 Long-term result after osteotomy. (A) Before operation, this 56 year old woman had a varus deformity of 12 degrees. (B) Immediately after corrective osteotomy. The anatomical alignment was valgus 9 degrees. (C) Eight years after corrective osteotomy. A B C Fig. 3 Long-term result after osteotomy. (A) Before operation, this 65 year old woman had a varus deformity of 4 degrees. (B) Four months after corrective osteotomy, the anatomical alignment was valgus 7 degrees. (C) Ten years after corrective osteotomy.

5 Vol. 2 No. 5 October 2008 High tibial osteotomy for patients under and over 60 years 385 follow-up of 7.42 years (Table 2). Survivorship analysis for patients who were less than 60 years old showed the probability of survival (with 95 percent confidence interval), with total knee arthroplasty as the end point, was 100 percent at 5 years and 78.13±11.28 percent at 10 years. In the other group of over 60, survivorship analysis showed the probability of survival (with 95 percent confidence interval), with total knee arthroplasty as the end point, was 98.3±1.65 percent at 5 years and 83.21±9.94 percent at 10 years (Fig. 4). There were some complications in the dome high tibial osteotomy. In the group in which ages were less than 60 years, there were three cases (6%) of transient peroneal palsy. All recovered after three months. There were three cases (6%) of unrelieved or recurrent pain that necessitated total knee arthroplasty secondary to failed high tibial osteotomy during follow-up. In the other group with ages over 60, there were four cases (6.67%) of transient peroneal palsy. All recovered after three months. There were three cases (5%) of unrelieved or recurrent pain that necessitated total knee arthroplasty secondary to failed high tibial osteotomy during follow-up. Two patients (3.33%) developed delayed union and needed additional cast-brace immobilization after removal of Charnley s external fixator to achieve bone union. There were two cases (3.33%) of pin tract infections, which were treated with intravenous administration of antibiotics (750 milligrams of Zinacef three times a day for three days followed by one week of oral administration of Zinnat after discharge) (Table 3). Table 2. Clinical outcome of patients. Variables Age<60 years Age>60 years P-value Preoperative femorotibial angle (varus) 4.39 (±4.43) 5.03 (±5.60) Postoperative femorotibial angle (valgus) 6.48 (±2.36) 7.56 (±3.18) Duration of follow-up (years) 7.68 (±2.36) 7.42 (±2.27) Preoperative Knee Society score (±1.17) (±3.90) 0.000* Postoperative Knee Society score (±8.15) (±5.82) Functional grading good 43 (86.0%) 53 (88.3%) fair 4 (8.0%) 4 (6.7%) poor 3 (6.0%) 3 (5.0%) Plus-minus values are mean±sd. *Statistically significant. Percent Survival Time (Years of follow-up) Fig. 4 Kaplan-Meier survival curve with Hall-Welner 95 percent confidence intervals, with the performance of an arthroplasty as the end point.

6 386 P. Tienboon, S. Atiprayoon Table 3. Complications of patients. Age<60 years (n=50) Age>60 years (n=60) Complications Number of patients (percent) Number of patients (percent) Transient peroneal palsy 3 (6.00%) 4 (6.67%) Unrelieved pain 3 (6.00%) 3 (5.00%) Delayed union 2 (3.33%) Pin tract infection 2 (3.33%) Discussion Satisfactory results were obtained with dome high tibial osteotomy in pain relief related to medial gonathrosis. There are many types of osteotomies. Closing lateral wedge osteotomy was the most common osteotomy for medial compartment osteoarthritis and apposition of orientation and resection of bone surfaces facilitates prompt healing. It achieved a more accurate correction with less morbidity than opening wedge osteotomy [11]. Its disadvantages were more difficulty in controlling tibial slope, intraoperative adjustments were more difficult, proximal tibiofibular joint violation, increased risk to peroneal nerve, altering the shape of the upper part of the tibia with implications for the joint reconstruction, bone shortening that might alter patellar height and might decrease tibial inclination. Opening wedge osteotomy provided more versatility intraoperatively, with the surgeon being able to manipulate the osteotomy site after the initial bone cut and avoid the violation of the proximal tibiofibular joint. It also had many disadvantages such as a longer period of restricted weightbearing postoperatively, often requiring bone graft with attendant harvest morbidity, higher risk for nonunion, might overlengthen the extremity, might alter patella height and might increase tibial inclination. Double level osteotomy was an alternative for patients with severe deformity in whom single osteotomy would potentially and adversely alter the obliquity of the joint line [12]. But its major disadvantage was potential additional morbidity from complication of surgery. The classic dome osteotomy popularized by Maquet [13] is still used frequently. It has many advantages such as allowing greater correction with less effect on the resultant joint line obliquity and should potentially be considered for varus deformities exceeding 20 degrees, the position of the tibial tubercle in relation to the joint line is unaffected, use of an external fixator allowed postoperative adjustment of alignment and absence of internal hardware. Maquet actually advocated anterior displacement of the tubercle through the osteotomy to relieve patellofemoral pain. However, it still has a few disadvantage such as the cumbersome nature of the treatment for patients and the technical demands of the procedure. Survivorship analysis and long-term evaluation of HTO suggests that passage time was the most important factor in determining the result of this procedure. According to Flecher [14], a year follow-up study of closing wedge HTO, survival was 92% at 10 years and 85% at 20 years with revision as the endpoint. Nagi [15] reported that combined lateral closing and medial opening-wedge HTO, survival was 92% at 10 years, 80% at 15 years and 58% at 20 years with TKA as the endpoint. According to Weale [16], high tibial osteotomy using a dynamic axial external fixator, survivorship at 5 and 10 years was 89% and 63%, respectively. From this study of dome high tibial osteotomy with Charnley s external fixator fixation in patients less than 60 years old survival was 100 percent at 5 years and 78.13±11.28 percent at 10 years. The other group in which ages were more than 60, survival was 98.33±1.65 percent at 5 years and 83.21±9.94 percent at 10 years. The difference between the two groups was not significant. The lower rate of deterioration in the series may be the result of the strict criteria applied to patient selection, the minimal invasive operative technique and emphasis on an exact postoperative alignment of 6 to 10 degrees as the prerequisite for the longest possible relief of symptoms after osteotomy. Patients with advanced two or three compartment osteoarthritis were treated with total knee replacement. Also, the number of patients in the following ten years or more was too small to permit a statement as to the observed rate of late deterioration. In our technique, dome high tibial osteotomy fixed with Charnley s external fixator, except for the difference of the severity of the osteoarthritis of the knee that in the younger group

7 Vol. 2 No. 5 October 2008 High tibial osteotomy for patients under and over 60 years 387 had preoperative Knee Society scores less than the older group, the results of HTO in older patients were comparable with the results in younger patients. We suggest that osteotomy should not be denied to patients older than sixty years of age if the other criteria for the procedure are met. The incidence of complications of peroneal palsies and unrelieved or recurrent pain that necessitated total knee arthroplasty secondary to failed high tibial osteotomy in the two groups is quite similar. The 6% incidences of transient peroneal palsies were observed in this study. Fibular osteotomy in proximal one-third had been reported to be associated with a high incidence of this complication [17]. The alternative approach of fibular osteotomy below the middle onethird level should be considered. After we changed the osteotomy site of fibular to the middle one-third, the incidence of transient peroneal palsy declined much more. In the older group, there was more incidence of delayed union and pin tract infection than in the younger group. Delayed union occurred 3.33 percent in older patients. The cause of delayed union might be problems of quality of bone or osteoporosis that required a longer time for union. In patients who had problems of delayed union, many needed additional cast-brace immobilization after removal of Charnley s external fixator to achieve bone union. Pin tract infection also occurred 3.33 percent in older patients. The softer bone in the older patients probably caused pins to loosen earlier than in the younger patients, and the possibility of low immunity in the older patients might also cause more pin tract infection than in the younger patients. This was usually treated using intravenous antibiotics for a few days. Therefore, we tried to reduce the risk of infection and delayed union using the minimal invasive technique that limited skin incision and aponeurosis splitting just by drilling holes before osteotomy. Because of no connection between the osteotomy site and upper pin site, pin tract infection would not spread to the osteotomy site. After we used this technique, the incidence of both delayed union and pin tract infection declined. The dome osteotomy as described combines an accurate overcorrection of the varus deformity and an anterior displacement of the patellar tendon, without any troublesome bulge below the knee. Plaster immobilization is avoided and immediate weightbearing is allowed. The application of an external fixator with pin fixation allowed postoperative alteration of axial alignment, if such were necessary. Earlier motion of the knee could be instituted. However, some complications occurred with pin fixation in this study and in other reports. It has been suggested that the most significant benefit of tibial osteotomy in younger, active patients is the buying of time before or delay of eventual arthroplasty. By correcting limb malalignment and redirecting force vectors away from the diseased medial tibiofemoral compartment, high tibial valgus osteotomy in older patients can be a definitive operation and total knee arthroplasty can be avoided. Subsequent to an osteotomy, a patient s physical activity is unlimited. Staheli et al. [18] reported that 31 of 35 patients treated with total knee arthroplasty (TKA) after a failed tibial osteotomy had a good or excellent result. Meding et al. [19] evaluated the results of 95 consecutive TKP in 82 patients at an average of 10 years and four months after high tibial osteotomy. The previous high tibial osteotomy had no adverse affect on the eventual results of the posterior cruciate ligament-retaining TKA performed with cement fixation. TKA after HTO is a more demanding procedure than primary TKA. Intraoperative difficulties are fewer in patients with no bone removal in the previous osteotomies. The results are comparable with those of primary TKA. In this study, compared to other studies, no significant difference was noted in the results of treatment of those patients more than sixty years old, compared with those younger than sixty years old at the time of osteotomy except for the complications of pin tract infection and delayed union. The most important factors related to continued satisfactory function were proper patient selection, good surgical technique and appropriate correction of the angular deformity. We would like to emphasize the minimal invasive technique limited to a small incision and aponeurosis-splitting only for drilling that may decrease the complications of infection and delayed union. Dome high tibial osteotomy results in a positive outcome and allows a pain-free, active lifestyle for several years. We highly recommend this procedure with minimal invasive technique in patients older and younger than 60 years in good selected cases that have limited activity, a decrease in the quality of life, varus malalignment and a desire to remain active.

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