A Combined Posterior Stable Prosthesis and Medial Condylar Sliding Osteotomy Technique for Kashin-Beck Osteoarthritis

Summary

This study evaluates a surgical technique combining a posterior-stabilized prosthesis with medial femoral condylar sliding osteotomy for Kashin–Beck disease. The approach effectively corrects knee deformities, restores function, and offers a simpler, reliable, and cost-effective alternative to constrained or hinged prostheses.

Abstract

Kashin–Beck disease (KBD) is a chronic, endemic osteoarthropathy characterized by progressive joint degeneration and deformity, frequently involving the knee and resulting in severe valgus alignment and functional impairment. Conventional surgical management of severe valgus deformities, including the use of condylar constrained knee (CCK) or hinged knee (HK) prostheses, is often associated with increased surgical trauma, higher costs, and limited accessibility, particularly in resource-constrained settings. This study evaluates a surgical technique combining posterior-stabilized (PS) total knee arthroplasty with medial femoral condylar sliding osteotomy to address severe valgus deformities in KBD. A retrospective analysis was conducted on 10 patients (11 knees) treated between 2019 and 2023. Clinical outcomes were assessed using pain scores, functional scoring systems, range of motion measurements, and radiographic evaluation of alignment and prosthesis stability. Postoperative results demonstrated significant improvements in pain, knee function, and activity levels, along with restoration of limb alignment and stable prosthesis fixation. The osteotomy site achieved satisfactory bone healing in all cases. This combined technique provides effective deformity correction and joint stabilization while reducing the need for highly constrained implants, offering a simpler, reliable, and cost-effective alternative for managing KBD-associated knee deformities.

Introduction

Kashin-Beck disease (KBD) is a regionally distributed endemic osteoarthropathy characterized by multiple symmetric degeneration and necrosis of epiphyseal, growth plate, and articular cartilage during skeletal development, followed by secondary degenerative joint disease. This condition commonly affects multiple joints systemically, with particularly prominent involvement of the knee and ankle joints¹. In China, KBD exhibits a unique belt-like geographical distribution extending from Heilongjiang Province in the northeast to Sichuan and Tibet in the southwest. According to the latest systematic review data, there was a negative correlation between KBD prevalence and the publication year; the prevalence rate of KBD is approximately 0.06%². Although newly diagnosed cases have declined significantly in recent years, epidemiological data indicate that approximately 170,000 existing cases remain nationwide¹. For patients with advanced KBD, severe knee deformities represent the primary cause of functional disability, with complex pathological changes posing substantial challenges to clinical management.

Total knee arthroplasty (TKA) is an effective intervention for restoring joint function in patients with end-stage KBD-associated arthritis^1,3,4,5,6,7. Traditionally, cases complicated by severe deformities have often required constrained condylar knee (CCK) prostheses or hinged-knee prostheses to achieve adequate mechanical stability. However, these highly constrained prostheses are associated with increased surgical trauma, elevated prosthetic-bone interface stress, and significantly higher costs. These factors create substantial barriers to their widespread adoption and patient acceptance, particularly in KBD populations where medical resources are relatively scarce and financial capacity is limited.

To develop a more suitable therapeutic strategy that balances functional reconstruction requirements with economic feasibility for KBD patients, our research team has employed posterior-stabilized (PS) knee prostheses combined with a medial femoral condylar sliding osteotomy (MFCSO) to treat severe valgus deformities of the knee. This approach aims to use standard PS prostheses while achieving deformity correction and restoring joint stability through precise osteotomy techniques. Preliminary clinical applications have demonstrated promising outcomes, as summarized and reported here.

Protocol

This study was conducted in accordance with the ethical principles outlined in the Declaration of Helsinki and was approved by the Medical Ethics Committee of Xianyang Central Hospital (Approval No. 2022-IRB-02). Written informed consent was obtained from all participants prior to their inclusion in the study.

Clinical data

This retrospective study included 10 patients (11 knees with valgus deformity) treated for valgus knee deformity related to KBD at the Department of Sports Medicine and Joint Surgery between November 2019 and December 2023. The cohort comprised 6 male and 5 female patients, with 6 left knees and 5 right knees affected. Representative cases are shown in Figure 1 and Figure 2 (e.g., a 53-year-old male patient). The mean disease duration was (26.91 ± 3.19) years (range, 15–50 years), the mean age was (60.73 ± 1.36) years (range, 53–69 years), the mean body mass index (BMI) was (18.86 ± 0.75) kg/m², and the mean follow-up duration was (32.5 ± 4.25) months.

Inclusion criteria were: (1) Diagnosis of KBD knee osteoarthritis (diagnostic criteria: WS/T 10026—2024); (2) Krackow type II valgus knee deformity³ with a tibiofemoral angle > 20°; (3) Age > 18 years; (4) Knee pain refractory to conservative management; (5) Scheduled for primary unilateral total knee arthroplasty; (6) Absence of severe cardiopulmonary dysfunction or coagulopathy.

Exclusion criteria were: (1) neuromuscular disease affecting knee function; (2) severe extra-articular deformity; (3) severe osteoporosis; (4) obesity (BMI > 30 kg/m²); (5) previous knee surgery or fracture history; (6) active systemic infection.

Surgical approach and initial exposure

The patient was positioned supine. A standard midline skin incision was made over the knee, followed by a medial parapatellar arthrotomy. The hypertrophic synovium, medial and lateral menisci, and both the anterior and posterior cruciate ligaments were excised.

Distal femoral osteotomy

The distal femoral cut was performed using intramedullary guidance. The entry point for the intramedullary rod was selected approximately 1 cm anterior to the insertion of the posterior cruciate ligament in the intercondylar notch and positioned slightly medial (2–3 mm) compared with conventional total knee arthroplasty. The valgus angle was determined based on the patient-specific femoral distal valgus angle (FDA) measured from preoperative full-length radiographs, typically ranging from 3° to 5°. In cases of severe valgus deformity (tibiofemoral angle > 25°), a 5° valgus angle was selected to facilitate lateral gap balancing. Resection thickness was initially set at 9 mm, with an additional 2–4 mm of bone removed depending on the degree of lateral condylar hypoplasia to ensure adequate lateral support following osteotomy. In cases of lateral femoral condyle defects, bone deficiencies were reconstructed using 3.5 mm cortical screws combined with cement augmentation.

Proximal tibial osteotomy

The proximal tibial cut was performed using extramedullary guidance. The osteotomy was oriented perpendicular to the tibial mechanical axis in the coronal plane, with a posterior slope of 3°. Rotational alignment of the tibial component was established using the line connecting the medial border of the patellar tendon and the midpoint of the posterior cruciate ligament as reference landmarks.

Femoral preparation

Femoral component size was determined based on the posterior condyles. Component rotation was aligned parallel to the surgical transepicondylar axis. Femoral bone cuts were completed using a four-in-one cutting block.

Lateral release

Following insertion of the spacer block, the medial and lateral gaps were assessed in full extension and at 90° of flexion. When the lateral gap was tight and the medial gap relatively loose, a sequential lateral soft tissue release was performed. Osteophytes were removed from the lateral femoral condyle and the posterolateral tibial plateau. At the joint line, a pie-crusting release of the iliotibial band was performed using an injection needle (Type: 1.2×32TWLB). If tightness persisted, the posterolateral joint capsule was released. Care was taken to protect the popliteus tendon and the common peroneal nerve. Release was continued until the lateral gap accommodated the planned thickness of the polyethylene insert.

Medial femoral condylar sliding osteotomy

This procedure was performed when the medial gap remained more than 4 mm larger than the lateral gap after lateral release.

A. Osteotomy design and execution

A sagittal plane osteotomy of the medial femoral condyle was performed using an osteotome rather than an oscillating saw. The osteotomy included the footprint of the proximal attachment of the medial collateral ligament. The osteotomy fragment thickness was maintained at approximately 8 mm (range, 5–8 mm).

B. Fragment shift and fixation

The osteotomy fragment, along with the attached medial collateral ligament, was shifted proximally and slightly anteriorly. Stability in extension and flexion was assessed using spacer blocks of equal thickness until balanced medial and lateral tension was achieved. The fragment was fixed to the femur using two to three 3.5 mm cortical screws, directed from anteroinferior to posterosuperior, while avoiding penetration into the intercondylar notch and the region potentially occupied by a femoral stem.

Patellar tracking and final implant placement

After placement of the trial components, patellar tracking was assessed using the no-thumb test. In cases of lateral patellar tilt or subluxation, a lateral retinacular release was performed until central tracking within the femoral trochlear groove was achieved. If tracking remained suboptimal, medial patellar facetectomy was considered to improve patellofemoral articulation. The goal was to achieve optimal tracking with a negative no-thumb test. Final implantation was performed using cemented, posterior-stabilized, fixed-bearing total knee prostheses from the same domestic manufacturer. Figure 3 shows some photos of the surgical procedure.

Postoperative management

Immediately after recovery from anesthesia, patients began ankle pump exercises and isometric quadriceps contractions under the guidance of physical therapists. On postoperative day 1, radiographic evaluation was performed to assess prosthesis placement. Prophylactic antibiotics were administered for 24 h, anticoagulation therapy was continued for 35 days, and an adjustable lower limb orthosis was applied for knee protection. Rehabilitation progressed as follows: non-weight-bearing knee flexion exercises were initiated on postoperative day 2; partial weight-bearing was allowed within 1 month; and full weight-bearing was achieved by 2 months. Radiographic confirmation of osteotomy healing was obtained within 3 months, after which the orthosis was discontinued.

Functional evaluation parameters

Follow-up assessments were conducted at 1, 3, 6, and 12 months postoperatively, and annually thereafter. Preoperative and final follow-up data were recorded for analysis. Outcome measures included pain assessed using the Visual Analogue Scale (VAS), function evaluated using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and range of motion measured with a standard goniometer. Knee-specific scores included the Knee Society Score (KSS) and the Hospital for Special Surgery (HSS) knee score. Activity level was assessed using the University of California, Los Angeles (UCLA) activity score. Radiographic evaluation included measurement of tibiofemoral angles on full-length standing radiographs using the institutional PACS system, and assessment of prosthesis positioning according to standard radiographic criteria.

Statistical analysis

Data were analyzed using SPSS 21.0 statistical software. Continuous data are presented as mean ± standard deviation. Paired t-tests were used to compare preoperative and postoperative parameters. A p-value of ≤ 0.05 was considered statistically significant.

Results

Comparison of knee pain scores

Preoperative scores on VAS and WOMAC were 7.55 ± 0.93 and 71.09 ± 7.13, respectively. Postoperative scores improved to 1.18 ± 0.40 and 7.09 ± 3.24, respectively. A paired t-test revealed that these improvements were statistically significant (p < 0.01; Table 1).

Knee joint functional score comparisons

Preoperative scores were as follows: KSS-clin...

Discussion

The primary objectives of TKA are to restore lower-limb mechanical alignment and achieve balanced medial-lateral soft-tissue tension. However, achieving these goals is particularly challenging in patients with Krackow type II valgus deformities exceeding 20°. Excessive soft tissue release can lead to postoperative instability, necessitating constrained or hinged prostheses, which are associated with increased wear rates, shorter longevity, and compromised proprioception. Pang et al.⁸ showed t...

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Knee Prosthesis – Femoral Condyle	Beijing Lidakang Technology Co., Ltd.	50120P	Model: RY A201; Material: CoCr
Knee Prosthesis – Tibial Tray	Beijing Lidakang Technology Co., Ltd.	50130	Model: RY B401; Material: CoCr + Ti
Knee Prosthesis – Tibial Insert	Beijing Lidakang Technology Co., Ltd.	50140P-9	Model: RY C401; Material: PE
Bone Cement (PALACOS R+G)	Heraeus Medical GmbH	LOT 76171594	Material: Polymethyl methacrylate (PMMA)
Metal Bone Screw (Cortical)	Tianjin Zhengtian Medical Equipment Co., Ltd.	T500035028	Model: HA004; Material: T (Material Code)
Disposable Sterile Injection Needle (C)	Zhejiang Kangkang Medical Devices Co., Ltd.	230715	Model: 1.2×32TWLB; Material: Not stated
SPSS 21.0 statistical software	IBM Corp	Version 21.0	Used for statistical analysis