Subchondroplasty for treating bone marrow lesions in osteoarthritic knee – initial experience

INTRODUCTION

Osteoarthritis (OA) is a condition that impacts all of the tissues in a joint ^1,2. Evidence suggests that the subchondral bone is the most important component in both pain genesis and disease progression ^3,4. . Magnetic resonance imaging (MRI) findings of bone marrow lesions (BMLs), or alterations in subchondral bone, are becoming more well-known in stress injuries, trauma, and osteoarthritis ⁵. Studies on the natural history of arthritis show a strong link between BMLs and pain (both the presence and severity) ^(6,7,8), as well as a faster advancement to total knee arthroplasty (TKA), ^9,10. Arthroscopic surgery used to be the most widely performed surgical procedure for degenerative knee disease ^11,12. Even with many guidelines showing that there is little short-term improvement still ^13,14, there are many indications for arthroscopy as displaced torn meniscus, loose body, microfracture, abrasion chondroplasty⁽¹¹⁾.

 Although total knee arthroplasty has proven to be a long-lasting treatment that provides consistent pain alleviation and enhanced function, it’s a significant surgical procedure that is costly, and it can be associated with severe complications and the need for revision in younger patients ^15-16  Therefore, there is an interest in therapies aiming at the subchondral bone as the main target of the treatment of knee osteoarthritis ⁽¹⁷⁾.  Subchondroplasty is a procedure for treating bone marrow lesions that involves injecting a bone substitute material like calcium phosphate cement or hydroxyapatite (HA) into the compromised subchondral bone under fluoroscopic guidance to provide mechanical support and initiate osseous remodeling to relieve pain and change the course of OA. ^17,18 The literature reports in the previous few years have demonstrated that the procedure is non-invasive and efficacious with minimal complications. ^(17-24) the goal of this prospective outcome study is to evaluate the efficiency of subchondroplasty in osteoarthritic individuals having BMLs. It was believed that Subchondroplasty would reduce pain and improve function while delaying TKA. This is the first study in Egypt to review patient-related Subchondroplasty outcomes and provide guidelines for the procedure's introduction into clinical practice.

PATIENTS AND METHODS

Study design:

This prospective one-year follow-up case study included 30 patients who were enrolled between February 2019 and February 2021. The institutional review board authorized the study, and every participant provided written informed permission.

Inclusion criteria

Age 40–75 years, for at least 3 months, atraumatic knee pain and impaired functioning, failures of conservative therapy for at least 3 months, ), moderate to severe osteoarthritis (Kellgren-Lawrence grading 3– early grade 4 ^(26), BML (femoral condyles and tibial plateau) on MRI scanning, localized pain in the BML region, and a signed informed agreement to participate in this research were the inclusion criteria for this study.

Exclusion criteria

Patients with knee pain and functional limitations caused by other conditions such as fractures, osteonecrosis, infection, tumors, or inflammatory arthritis have been excluded from the study, as have those with gross ligamentous instability, and coronal axis malalignment > 8 degrees in varus/valgus, ( tri-compartmental   grade 4 arthritis with complete bone contact)

Endpoints:

All of the patients were evaluated clinically, radiologically, and with an MRI. Preoperatively, and at two weeks, three months, six months, and twelve months postoperatively, they were assessed using the WOMAC score, and the pain was recorded using the VAS score. X-rays were taken of all of the patients immediately following therapy, as well as 3, 6, and 12 months afterward. Complications during and after surgery were also documented.

Surgical Technique:

 After prior planning, the SCP technique was done on the patient in a supine posture under spinal anesthesia.

According to preoperative planning, the cannula entry point was indicated on the skin using fluoroscopy in both frontal and lateral views. The majority of the studied patients have large BMLs that are not confounded to points requiring precise identification and triangulation. Unlike standard SCR techniques, no jigs were used, instead, awls or guidewires were applied, and drilling was done 1-2 cm away from the joint line, either parallel or oblique to the joint line, or through the epiphyseal scar from the opposite side of the knee to avoid overpressurizing the subchondral bone as well as prevent extravasation into soft tissues. Using curved awls, reamers, and various dilatation devices, expanding and dilatation of the injection site to optimize subchondral bone. After that, the cannula was inserted, and drilling proceeded till the lesion was approached. The bone substitute substance which is nanocrystal hydroxyapatite cement,( QOssHeal IHA .G.SURGIWEAR LTD, Shahjahanpur, India), was then prepared and injected into the area, with fluoroscopy used to check its distribution.

Fig 1: Subchomdroplasty technique. A: preoperative x-ray, AP and lat., views. B: MRI, Subchondral bone marrow lesions in the medial tibial & femoral sides. C: Localization of injection area with guidewire under fluoroscope D: Introducing injection cannula  : Injection is completed F: Postoperative x-ray: injectable  material is in place 

Postoperative care:

 involved controlling postoperative pain (which could be severe) and partial weight-bearing with crutches for two weeks. Following that, full weight with no restrictions on the range of motion was permitted. Returning to everyday routines as soon as tolerated was recommended, which could take anywhere from 2-4 months.

Statistical Analysis: The Statistical Package for Social Science (IBM SPSS) version 23 was used. The mean, standard deviations, and ranges of parametric data have been reported. The median and inter-quartile range (IQR) have been used to present nonparametric data. The Chi-square test, as well as the Fisher exact test, have been employed to compare groups with qualitative data. The Paired t-test has been employed to compare two groups that have a parametric distribution. Willcoxon test has been used to make a comparison between the two paired groups with the nonparametric distribution. In addition, the Friedman test and Spearman correlation coefficients have been employed to evaluate the relationship between two quantitative parameters in the same group. The significance of the p-value has been determined as follows: P < 0.01: Highly significant, P < 0.05: Significant.

RESULTS

Table (1) summarises the following: 70% of the patients (21 of 30) were females with an average age of 58 years (range 40.0–70.0) and a BMI of 29.7 kg/m2 (range 22.5–37.7 kg/m2). Patients had been experiencing symptoms for an average of 38 months (range 10-180 months) before surgery, with osteoarthritis KL grading of 21 patients KL grade 3 and 9 patients KL  grade 4. The site of bone marrow lesion was combined tibial & femoral lesions, with the affection of medial tibial plateau in (100 %) of cases, medial femoral lesions in (86.6 %), lateral femoral in(6.7 % ) and both lateral and medial femoral lesions in (6.7 %), The majority of the studied patients have extensive BMLs. Patients rated their preoperative pain on a VAS scale of 6.9 out of 10 (range 5–9). At the start of the study, the average WOMAC score was 62.03. (range 41-81).

Table 1: Comparison of the two groups evaluated. IQR: interquartile range, SD: standard deviation.

Changes in pain score (VAS) Overall, the average VAS scores improved significantly after surgery. By the conclusion of the year's follow-up, the patient had improved from 6.98 +-1.16 to 1.81 +-1.00 (p<0.01)

Fig 2: Follow up for VAS score at different times of measurement.

Fig 3: Comparison between WOMAC score at different times of measurement. Function:black line.stiffness :pink ,pain:blue.

There was no statistically significant correlation between the outcome measures (VAS and WOMAC) scores and: Patient demographics: except for a positive correlation with BMI and a positive correlation with the duration of pain. There is a negative correlation between KL scores and improved outcome scores, especially for pain and stiffness.

Table 2: Correlation of the studied scores at one year with the other variables. Spearman correlation coefficients.