Simultaneous bilateral open wedge high tibial osteotomy versus simultaneous bilateral unicompartmental knee arthroplasty in the treatment of bilateral medial knee osteoarthritis: a retrospective study of an average three-year follow-up

Abstract

Objective

There is growing evidence that simultaneous bilateral open wedge high tibial osteotomy(SBOWHTO) and simultaneous bilateral unicompartmental knee arthroplasty(SBUKA) is an effective surgical treatment for bilateral medial knee osteoarthritis (MKOA). However, which intervention is more beneficial for bilateral MKOA patients remains unknown. Therefore, the aim of this study was to compare the effectiveness of these two strategies through early clinical outcomes, complication rates, and prosthetic survival.

Methods

The clinical data of 60 patients with bilateral MKOA admitted to the Affiliated Hospital of Qingdao University from January 2018 to December 2022 were retrospectively analyzed, and they were divided into SBOWHTO group (n = 28) and SBUKA group (n = 32) according to different treatment methods. Clinical relevant indexes, Hospital for Special Surgery (HSS) score, Knee Society Knee (KSS) score, range of motion(ROM), postoperative complications and prosthetic survival rate were compared between the two groups.

Results

Patients in the SBOWHTO group were followed up for 27 to 50 months, with an average of (37.18 ± 6.84) months. Patients in the SBUKA group were followed up for 24 to 59 months, with an average of (39.38 ± 9.74) months. There were no significant differences in postoperative KSS, HSS and ROM between SBOWHTO group and SBUKA group (p > 0.05). There was no significant difference in complication rate between the two groups (p = 0.721). There was no significant difference in prosthetic survival rate (p = 0.622) and prosthetic survival curve (χ2 = 0.546, p = 0.46) between the two groups.

Conclusions

This study compared early clinical outcomes, complication rates, and prosthesis retention rates after SBOWHTO and SBUKA, and found that the early clinical benefits of SBOWHTO and SBUKA were comparable in patients with bilateral MKOA.

Introduction

Knee osteoarthritis (KOA) is one of the most common diseases affecting human health, which is a chronic and degenerative joint disease caused by articular cartilage degeneration and mobility disorder caused by local joint injury, inflammation or chronic strain [1]. In recent years, with the change of population structure and the popularity of sports activities, the incidence of single-ventricular knee osteoarthritis, especially medial knee osteoarthritis (MKOA), which requires intervention, has increased in the young population, which has attracted the attention of joint surgeons. As the KOA concept of “step treatment” is widely accepted by joint surgeons, high tibial osteotomy (HTO) and unicompartmental knee arthroplasty (UKA) have been proven to be reliable methods for the treatment of MKOA. It has become a more cost-effective alternative treatment than total knee replacement (TKA) [2, 3]. HTO is designed to correct the extraarticular deformities that cause abnormal knee load and the resulting wear of intraarticular cartilage, while UKA focuses on repairing the worn medial tibiofemoral compartment and restoring the anatomical, kinematic and physiological balance of the knee [2, 4]. Nonetheless, which intervention is more beneficial in the treatment of MKOA remains controversial in the current literature.

Previous studies have confirmed that HTO and UKA are safe and effective surgical interventions under the correct inclusion/exclusion criteria [2, 3]. With the increasing perfection of joint surgery techniques, the indications of both are gradually expanding, and although the “ideal” indications of HTO and UKA are different, there are still many patients who are considered to meet the conditions of these two surgeries. More and more studies have explored the differences in clinical efficacy after HTO and UKA, but these studies mainly focus on the comparison of unilateral HTO and UKA [5, 6]. Interestingly, most pronation alignments do not occur in isolation. Although exact numbers are not available in the literature, bilateral MKOA with varus deformity is a common condition. The presence of bilateral disease appears to be the result of the high incidence of varus of the knee joint [7, 8]. For patients with bilateral MKOA, the treatment modalities mainly include two-stage surgery and one-stage bilateral surgery. To date, simultaneous bilateral knee surgery is not new, as MKOA generally affects both knees, and this feature may be particularly true for individuals with a large number of bilateral varus [9]. Two stages of continuous treatment may involve repeated hospitalizations, costs, recovery, rehabilitation, and the burden of functional and economic disability. Simultaneous bilateral surgery may reduce this burden and therefore may be a valuable alternative to two-stage surgery for patients with bilateral MKOA with varus malformations [10]. So in the current clinical study, simultaneous bilateral open wedge high tibial osteotomy(SBOWHTO) and simultaneous bilateral unicompartmental knee arthroplasty(SBUKA) has been increasingly applied to patients with bilateral MKOA and has gradually become a popular choice [9, 11].

SBOWHTO and SBUKA have not been properly compared in the previous literature, and the advantages between the two procedures are unclear. Therefore, this study retrospectively analyzed the clinical data of patients with SBOWHTO and SBUKA, and compared the differences in the early postoperative clinical efficacy, complication rate and prosthesis preservation rate of these two types of surgery. This result may provide guidance and data support for surgeons to choose the surgical method.

Materials and methods

Inclusion and exclusion criteria

Data of 87 patients with bilateral MKOA treated by SBOWHTO and SBUKA in Affiliated Hospital of Qingdao University from January 2018 to December 2022 were retrospectively analyzed. Inclusion criteria: ① diagnosis of bilateral MKOA; ② From January 2018 to December 2022, he received SBOWHTO or SBUKA treatment in the Affiliated Hospital of Qingdao University. Exclusion criteria: ① Other procedures were performed at the same time as SBOWHTO or SBUKA; ② Patients with anemia, myocardial infarction, cerebral infarction, coagulation dysfunction, deep vein thrombosis in the past 6 months; ③ Patients with diseases other than MKOA that may affect knee function, such as polio, myasthenia, and neurological disorders; ④ History of traumatic arthritis, rheumatoid arthritis and knee infection; ⑤ Previous ligament and meniscus injuries or a history of knee surgery; ⑥ Patients with missing follow-up or missing clinical data. A total of 27 patients were excluded from the study based on inclusion/exclusion criteria. Therefore, in the end, this study consisted of 60 patients, who were divided into SBOWHTO group (n = 28) and SBUKA group (n = 32) according to different treatment methods. The study was approved by the Ethics committee of the Affiliated Hospital of Qingdao University(Approval No.: QYFYWZLL28296), and all patients signed informed consent forms.

Surgical procedures

For SBUKA, the medial parapatellar incision was made, which was dissected layer by layer to reveal the medial compartment of the knee joint. After evaluating the integrity of the anterior cruciate ligament, the hyperplastic syvium and osteophyte were cleared, and the medial meniscus was resected. Standard osteotomy of tibia and femur was performed respectively, the appropriate size of joint prosthesis was measured and selected, the flexion and extension space was balanced, and after the flexion and extension stability was tested, antibiotic bone cement was mixed and fixed. After operation, the knee joint was checked for good movement, rotation without gasket dislocation, suture to close the incision, sterile dressing and elastic bandage pressure dressing.

For SBOWHTO, an oblique incision about 6 cm long was made on the medial tibial tubercle to expose the proximal anseropodium of the tibia and the superficial layer of the medial collateral ligament, and free the medial collateral ligament at the tibial end. At the upper edge of the foot of the anserus, two kirschner wires were inserted into the tibia parallel to the tip of the fibula small head. After the position and depth of the osteotomy were determined by fluoroscopy, the bone was cut close to the lower edge of the Krantler needle with a swinging saw. The bone knife was superimposed into the tibia in turn, and the suitably varion stress was applied to the tibia, and the end of the osteotomy was slowly opened with a spinner. According to the Angle of tibia varus before operation, the brace degree was determined to make the lower limb force line consistent with the preoperative plan. The force line of C-arm was determined by fluoroscopy to be satisfactory, and Tomofix plate and screw were placed to fix it. After hemostasis, the incision was sutured and drainage tube was placed. After the operation, sterile dressing was covered with elastic bandage and pressure bandaged.

Perioperative management

The rehabilitation protocol was standardized. Patients were allowed to walk with full weight-bearing (using mobility aids) on day 1 after surgery. All patients were given compression bandages and ice packs to elevate affected limbs. All patients underwent ankle pump training. The drainage tube was opened 4 h after placement, and the drainage tube was removed within 24 h (< 50 ml) after operation, and the drainage flow was recorded. Rivaroxaban 5 mg, qd, was taken in the postoperative 24 h to prevent DVT.

Outcomes

General patient information was collected from the hospital’s electronic medical record system, including patient age, gender, course of illness, body mass index(BMI), and time of surgery. Preoperative and postoperative functional scores and patient clinical data were collected and recorded by independent professionals. Clinical outcomes were evaluated using Hospital for Special Surgery (HSS) score, Knee Society Knee (KSS) score and range of motion (ROM) [12, 13]. The HSS knee score is a scoring system proposed in 1976 by the American Second Hospital of Special Surgery to evaluate knee joints before and after surgical procedures. This scale assesses six key aspects: pain, function, ROM, muscle strength, knee fexion deformity, and knee instability [12]. The KSS evaluates objective and subjective clinical and functional knee parameters. Total scores ≤ 70 were considered poor, while scores of 71–80 were fair, scores of 81–90 were good, and scores of 91–100 were excellent. The postoperative complications and prosthesis revision were obtained by outpatient review and telephone follow-up. A revision was defined as the removal, exchange, or addition of an implant component, including bearing exchange for bearing dislocation, or conversion to TKA.

Statistical analysis

SPSS25.0 statistical software was used for analysis. The measurement data corresponded to normal distribution and were expressed as mean ± standard deviation. The normality of continuous variables was determined by the Kolmogorov-Smirnov test or the Shapiro-Wilk test in SPSS. Paired T-test was used for comparison between groups. The qualitative data of the two groups were compared by chi-square test or Fisher’s Exact Test. The revision was evaluated using Kaplan–Meier survival analysis. Significance was set at P < 0.05.

Results

General results

A total of 60 patients were included in this study, and were divided into two groups according to different surgical methods (Fig. 1and Fig. 2) : SBOWHTO group (n = 28) and SBUKA group (n = 32). There were 7 men and 21 women in the SBOWHTO group; The mean age was (62.61 ± 6.42) years, the mean BMI was (28.57 ± 3.94) Kg/m², the mean follow-up time was (37.18 ± 6.84) months, and the mean operation time was (121.07 ± 24.51) minutes. The SBUKA group consisted of 8 males and 24 females; The mean age was (61.47 ± 7.16=) years, the mean BMI was (27.35 ± 3.74) Kg/m², the mean follow-up time was (39.38 ± 9.74) months, and the mean operation time was (123.41 ± 18.46) minutes. There were no differences in age, BMI, sex, operation time and follow-up time between the two groups (p > 0.05). The two sets of basic data are shown in Table 1.

Fig. 1

Typical case of simultaneous bilateral open wedge high tibial osteotomy. Pre-operative radiographs showed anteromedial osteoarthritis of both knees. (A) Full length weight bearing X-ray of both lower limbs; (B) Anteroposterior View; (C) Lateral View. Post-operative radiographs following simultaneous bilateral high tibial osteotomy. (D) Full length weight bearing X-ray of both lower limbs; (E) Anteroposterior View; (F) Lateral View

Fig. 2

Typical case of simultaneous bilateral unicompartmental knee arthroplasty. Pre-operative radiographs showed anteromedial osteoarthritis of both knees. (A) Full length weight bearing X-ray of both lower limbs; (B) Anteroposterior View; (C) Lateral View. Post-operative radiographs following simultaneous bilateral unicompartmental knee arthroplasty. (D) Full length weight bearing X-ray of both lower limbs; (E) Anteroposterior View; (F) Lateral View

Table 1 Cohort demographics

Functional evaluation

At the last follow-up, the KSS of the SBOWHTO group was (88.64 ± 4.91) points and that of the SBUKA group was (90.22 ± 4.6) points, with no significant difference between the two groups (t=-1.283, p = 0.204). At the last follow-up, the HSS of the SBOWHTO group was (88.86 ± 3.32) and that of the SBUKA group was (90 ± 4.14), with no significant difference between the two groups (t=-1.168, p = 0.248). Detailed data are shown in Table 2. At the last follow-up, the ROM of the SBOWHTO group was (124.21 ± 3.15)° and that of the SBUKA group was (122.91 ± 2.97)°, with no significant difference between the two groups (t = 1.654, p = 0.103). Detailed data are shown in Table 3.

Table 2 Comparison of the KSS and HSS among the two groups before the operation and at the last follow-up (x ± s)

Table 3 Comparison of the ROM among the two groups before the operation and at the last follow-up (°, x ± s)

Complications

Postoperative complications occurred in 5 cases in the SBOWHTO group, including 1 case of conversion to TKA, 1 case of blood transfusion within 72 h after surgery, 2 cases of lateral hinge fracture and 1 case of deep vein thrombosis, with a complication rate of 17.86%. There were 4 postoperative complications in the SBUKA group, including 1 conversion to TKA, 2 prosthesis dislocation and 1 incision infection, with a complication rate of 12.5%. The incidence of postoperative complications in SBOWHTO group was higher than that in SBUKA group (17.86% vs. 12.5%), but the difference was not statistically significant (p = 0.721). Detailed data are shown in Table 4.

Table 4 Complication rates in two groups

Implant revision status and implant survival rate

In the SBOWHTO group, 1 patient underwent revision surgery (conversion to TKA), and the survival rate was 98.21%. In the SBUKA group, there were 3 revision operations, of which 1 conversion to TKA and 2 revision were due to dislocation of the prosthesis. The survival rate of the prosthesis was 95.31%. The postoperative prosthesis survival rate in SBTHO group was higher than that in SBUKA group (98.21% vs. 95.31%), but the difference was not statistically significant (p = 0.622). As can be observed from Kaplan-Meier prosthesis survival curves of the two groups (Fig. 3), the prosthesis retention rate of the two groups gradually decreased with the increase of follow-up time. At the last follow-up, the retention rate of prostheses was similar in all groups (χ2 = 0.546, p = 0.46). Detailed data are shown in Table 5.

Fig. 3

The revision was evaluated using Kaplan-Meier survival analysis. No difference in the prosthesis survival curve was found among the two groups (χ2 = 0.546, P = 0.46)

Table 5 Survival rate of the implant in two groups

Discussion

The best treatment for patients with MKOA has been widely debated. Many surgical procedures have been reported, including arthroscopy, HTO, UKA, and TKA [1,2,3,4]. Both HTO and UKA are the most commonly used knee preservation procedures in KOA step therapy. HTO and UKA seem to compete, but they are very complementary surgical approaches. Together, they cover almost all of MKOA. The indications of HTO are more targeted and suitable for some relatively young patients with MKOA accompanied by a certain degree of tibial varus [2]. The main indication of UKA is anterior medial knee osteoarthritis, the criteria of which are severe medial cartilage wear, no lateral cartilage injury and complete ligament function [3]. It is known that MKOA often affects both knees, and this characteristic may be especially true for individuals with severe MKOA [9]. Since many bilateral MKOA patients require surgical intervention, SBOWHTO and SBUKA are not new. However, to the best of our knowledge, there have been no reports to date comparing the safety of SBOWHTO with SBUKA. Therefore, the purpose of this study was to retrospectively compare the safety of these two strategies.

In this study, there were no significant differences in postoperative HSS, KSS and ROM between SBOWHTO group and SBUKA group. In terms of clinical efficacy, the comparison of unilateral HTO to UKA has been controversial, which may be related to the difference in follow-up time and sample size. Previous studies have found that early postoperative UKA patients show better joint awareness than HTO patients. In addition, the joint awareness rate of UKA patients was faster than that of HTO patients [14]. In addition, Jeon et al. [15] retrospectively analyzed 26 cases of HTO and 21 cases of UKA in a study and found that the International Knee Documentation Committee score of patients in the UKA group was significantly higher than that in the HTO group 6 months after surgery. The improvement of activity level in UKA group was better than that in HTO group. Since HTO is a osteotomy, both ends of the osteotomy have not fully healed at 3 months after surgery, and increased activity may aggravate pain. In order to effectively reduce pain and symptoms, patients tend to be less active [16]. However, in UKA cases, the medial compartment surface has been replaced by an artificial joint, eliminating the source of pain and significantly reducing pain [17]. Studies have reported that the muscle strength of patients in the UKA group was higher than that in the HTO group 6 months after surgery, and the muscle strength of patients in the two groups was comparable at 1 year after surgery [18]. This indicates that compared with HTO, the knee joint function of patients after UKA treatment is significantly improved, and it is also safe, which can further stabilize the postoperative status of patients, reduce the pain response of patients, ensure the limb movement status of patients, and improve the prognosis of the disease. Unlike these studies, the meta-analysis of Cao et al. [19], Santoso et al. [20] and Han et al. [21] observed no significant difference in knee function scores after HTO and UKA.

In the comparison of ROM, there was no significant difference between postoperative ROM and HTO caused by UKA during a follow-up period of at least 1 year [16, 22]. On the contrary, Ivarsson [18] and Ryu et al. [23] had better ROM in the UKA group than in the HTO group 3–6 months after surgery. These findings may reflect a longer recovery process associated with HTO: As time after surgery lengthens, HTO patients eventually report ROMs comparable to UKA patients. This is the same as our findings. The average observation time in this study was 3 years, and the follow-up time was still short. With the extension of observation period, the clinical efficacy of both may change. Longer follow-up is therefore warranted in future studies.

When trying to choose the most appropriate surgical option for a patient, longevity or durability is an important consideration. Many previous studies have compared prosthesis survival rates in the early to middle period after UKA and HTO. Han et al. [21] showed that the revision rate of HTO was lower than that of UKA. However, a retrospective study with a follow-up of up to 10 years found that the survival rate after UKA was 8.5% higher than that of HTO, but it was not statistically significant [24]. A study of 110 patients [25] found that the 5 -, 10 -, 15 - and 20-year survival rates after HTO were 100%, 91.0%, 63.4%, and 48.3%, respectively, while the 5 -, 10 -, 15 - and 20-year survival rates after UKA were 90.5%, 87.1%, 70.8%, and 66.4%, respectively. There was no significant difference in long-term survival between UKA and HTO. Survival rates for UKA and HTO in both studies were similar to those in this study, with SBOWHTO patients having a higher survival rate (98.21%) than SBUKA patients (95.31%), but the difference was not statistically significant. However, there are limitations to the short follow-up time of this study, and proper evaluation of long-term outcomes will help better evaluate the survival of these two surgical modalities.

Both SBOWHTO and SBUKA are well-established treatments for MKOA, but direct comparison of postoperative complications between these two treatments has not been reported. Our study found that patients in the SBOWHTO group had a higher rate of postoperative complications than those in the SBUKA group (17.86% vs. 12.5%), but the difference was not statistically significant. In the unilateral comparison of UKA and HTO, the UI study found that UKA had fewer complications than HTO, and there were statistically significant differences in postoperative pain, revision rate and complications between the HTO and UKA groups (p < 0.05). UKA has less postoperative pain, fewer complications, and a higher functional score, while HTO provides greater ROM and lower revision rates [26]. A large-scale analysis found that UKA was associated with a lower rate of infection and less TKA conversion compared to patients receiving HTO. The incidence of dislocation, periprosthesis fracture and surgical site infection is also low in UKA patients [27]. However, a meta-analysis that pooled data from 11 comparative studies found no significant difference in postoperative complication rates between the HTO and UKA groups [28]. There was no difference in rates of venous thromboembolism, urinary tract infection, blood transfusion, and reoperation 30 days after surgery. Compared with UKA, HTO is associated with a higher incidence of superficial incision infection [29]. It is worth noting that in this study, there were 2 cases of Takeuchi type I lateral hinge fractures in the SBOWHTO group, all of which occurred during the operation. After TomoFix locking plate compression, the fracture ends were well interlocked, the fracture lines were fuzzy, and the patients underwent normal rehabilitation exercise after surgery, and the lateral hinge fractures were well healed. Lateral hinge fracture is the most common complication of HTO and a risk factor for surgical failure, which can lead to loss of correction Angle and delayed or non-union at the osteotomy in severe cases [30]. Previous studies have found that excessive osteotomy space and patients’ general conditions (age, gender, body mass index, osteoporosis and underlying diseases) are also risk factors for lateral hinge fracture [31]. Therefore, in view of the causes and mechanisms of lateral hinge fractures, it is particularly important to take effective preventive measures and improve surgical skills.

This study has some limitations. First of all, the surgeons who performed the surgery in this study were different, because the amount of surgery performed by one doctor could hardly meet the sample size requirements of this study. The effect of the surgery performed by different doctors on the clinical outcome is still unclear, but the doctors who performed the surgery were senior chief physicians, which ensured the reliability of the postoperative clinical efficacy to a certain extent. Second, no studies comparing SBOWHTO and SBUKA have been reported so far, so this report is very meaningful in itself, but the results of this study are difficult to compare with the results of other studies. Third, the average observation time of this study was 3 years, which is still a short follow-up time for the study of prosthesis retention rate. As the observation period is extended, the possibility of renovation may increase. Longer follow-up may be necessary in the future. Fourth, we only analyzed clinical data at the last postoperative follow-up, and data at other time points (such as 6 and 12 months after surgery) were unknown. More detailed clinical time course studies are necessary. However, we guarantee the integrity and reliability of the clinical data of the last follow-up patient. Fifth, due to individual differences of patients, postoperative rehabilitation measures are not exactly the same. Finally, the number of cases included in this study is small, and the patients treated and treated are all from our hospital, which has regional limitations, and it is necessary to further increase the sample size and conduct prospective studies in the later stage.

Conclusions

In this study, which compared early clinical outcomes, complication rates, and prosthesis retention after SBOWHTO and SBUKA, we found that the early clinical benefits of SBOWHTO and SBUKA were comparable in patients with bilateral MKOA.