Safety and early results of Subchondroplasty® for the treatment of bone marrow lesions in osteoarthritis: a systematic review

Subchondroplasty® (SCP) Provides Resolution of Symptoms and Functional Improvements in Mild-to-Moderate Knee Osteoarthritis with Persistent Bone Marrow Lesions: 12-Month Follow-Up Results from a Multicentric Open-Label Prospective Clinical Trial

Introduction. Bone marrow lesions (BMLs) are MRI-visible subchondral bone alterations, highly correlated with symptoms in the knee. Subchondroplasty (SCP) is able to fill the subchondral defects associated with BMLs using an injectable bone substitute material. The aim of the present study is to evaluate the 12-month outcomes of the SCP in the treatment of symptoms of mild-to-moderate knee osteoarthritis (OA) patients with persistent BMLs of the knee. Materials and Methods. Subjects affected by BMLs of the femoral condyle or tibial plateau that were present for >3 months and not responsive to conservative treatments were enrolled in this prospective multicenter trial. All the patients underwent SCP. Follow-up was conducted at 1, 3, 6 and 12 months. All subjects completed Numerical Rating Scale (NRS) for pain, Knee Injury and Osteoarthritis Outcome (KOOS) score, Euro Quality of life-5 dimensions (EQ-5D) score, and a subject global satisfaction scale. Demographic information of the patients was also collected. Results. A total of 79 patients completed the 12-month follow-up. Statistically significant improvements on all clinical scales were registered from baseline to the 12-month follow-up. No severe adverse events were reported. Four patients were considered failed. A 12-month subgroup analysis was performed to evaluate the possible correlation between all the KOOS subscales and age, gender, number of BMLs, location of BMLs, and Kellgren-Lawrence grade: no statistically significant associations were observed. Conclusion. SCP is a safe and effective procedure for the treatment of symptoms related to persisting BMLs in mild-to-moderate osteoarthritic knees, with a low failure rate up to 12 months' evaluation.

Complications Following Intraosseous Injections of Calcium Phosphate Bone Cement in Subchondroplasty

An alternative approach to the major problem of osteoarthritis that has begun to pique the interest of researchers focuses on the pathology of the subchondral bone, its constant cross-talk with the articular cartilage, and its interaction with the joint. The presence of bone marrow lesions, detectable on MRI scans, has proven to be a cause of pain as well as a predictor of the progression of degenerative changes. Subchondroplasty is a relatively new surgical procedure for the treatment of these lesions, in which injectable calcium phosphate bone cement is infused into the affected area percutaneously, under fluoroscopic guidance. In its use as a synthetic scaffold, calcium phosphate bone cement exhibits considerable osteoconductivity, bioabsorbability, and low toxicity, thus showing great potential for restoring subchondral biomechanical properties through structural remodeling. Although published results appear quite promising, there are certain complications that the surgeon should be aware of. We reviewed the published data regarding complications of the procedure, highlighting possible causes according to these data, and suggesting safety measures. Avascular necrosis of the talus is the most reported concern. Postsurgical pain, infection, and continuous wound drainage due to bone substitute material extravasation to the joint or soft tissue are also mentioned, necessitating further standardization of the procedure. There are no reports of permanent postoperative disability or fatal outcomes.

A novel retrograde technique for ankle osteochodral lesions: the sub-endo-chondral regenerative treatment (secret)

PURPOSE

To describe a new surgical technique for osteochondral lesions of the ankle, using bone marrow concentrate on a scaffold and homologous bone graft positioned through a retrograde approach. Many surgical options for ankle osteochondral lesions have been described, and the ideal treatment is still debated. Bone marrow stimulating techniques are recommended for cystic lesions, with some concerns regarding the healing potential of the subchondral bone. In case of wide osteochondral defects, regenerative solutions are preferred but a massive chondral debridement is usually required. To overcome these problems, a novel technique is proposed.

METHODS

The proposed technique was performed on patients affected by osteochondral lesions of the talus, either cysts with intact cartilage or wide osteochondral defects. A preoperative magnetic resonance imaging was obtained to localize the lesion. A 6-mm tarsal tunnel was retrogradely created toward the lesion, to allow a complete sub-endo-chondral debridement preserving the healthy cartilage. A hyaluronan scaffold soaked with a previously prepared bone marrow concentrate was retrogradely positioned under the cartilage surface and the tunnel was filled with homologous bone graft. Preoperative clinical scores and postoperative x-rays were registered.

RESULTS

Four patients were treated using this technique. No intraoperative and postoperative complications occurred. Good bone remodeling was observed at 12-week postoperative x-rays.

CONCLUSIONS

This technique combines the mini-invasiveness of retrograde drilling with the regenerative properties of biological scaffold soaked with bone marrow concentrate. Despite further research being needed, it seems a new viable solution to treat both subchondral cysts and large osteochondral defects of the ankle, whose management is still controversial.

What Factors are Associated With Conversion to Knee Arthroplasty After Subchondroplasty?

BACKGROUND

Subchondral bone marrow lesions identified on knee MRI are believed to play a role in osteoarthritis-associated pain. The subchondroplasty procedure is an arthroscopically assisted procedure for treating such lesions to avoid larger procedures such as knee arthroplasty. However, the survivorship free of conversion to arthroplasty and the factors associated with an increased likelihood of conversion of subchondroplasty to arthroplasty have not been well defined.

QUESTIONS/PURPOSES

We performed this study to (1) determine the 5-year survivorship of subchondroplasty free from conversion to knee arthroplasty (unicompartmental or total) and (2) identify variables that were associated with progression to knee arthroplasty after a subchondroplasty procedure.

METHODS

In all, 216 patients who underwent a subchondroplasty procedure performed by one surgeon with subchondroplasty experience at a single-center, multilocation facility between September 2014 and August 2017 were retrospectively evaluated to estimate survivorship free from conversion to knee arthroplasty at 5 years. The mean ± SD age and BMI at the time of subchondroplasty procedure were 59 ± 11 years and 33 ± 8 kg/m 2 , respectively; 60% (129 of 216) of the patients were women. Other variables collected were smoking status and grade and location of chondral lesions. The electronic medical record was reviewed to determine whether the patient had a knee arthroplasty after subchondroplasty. Survivorship free from conversion to knee arthroplasty at 5 years was calculated from a Kaplan-Meier survivorship estimator. Factors associated with progression to knee arthroplasty were examined using t-tests and chi-square analyses. Variables showing evidence of an association with knee arthroplasty were explored further using a Kaplan-Meier survivorship estimator (n = 190).

RESULTS

Kaplan-Meier survivorship free from conversion to knee arthroplasty was 73% (95% CI 67% to 79%) at 5 years after subchondroplasty. We found that age older than 50 years and Grade 4 chondral lesions were associated with conversion to knee arthroplasty. Patients with a Grade 4 chondral lesion had 5-year survivorship of 62% (95% CI 54% to 71%) and 59% (95% CI 50% to 69%) for those older than 50 years with a Grade 4 chondral lesion.

CONCLUSION

Currently, we recommend a detailed, informed discussion of the risks versus benefits with patients who are considering a subchondroplasty procedure, particularly patients aged 50 years and older and those with Grade 4 chondral lesions. Future randomized trials, including those that compare the subchondroplasty procedure with arthroscopy alone or nonoperative management options, are still needed to confirm the efficacy and role of the subchondroplasty procedure in patients with knee osteoarthritis, because only such prospective studies can determine the success of the procedure.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

A Retrospective Study Assessing the Clinical Outcomes After Cheilectomy and Subchondroplasty for Hallux Rigidus

Introduction Hallux rigidus (HR) refers to osteoarthritis of the first metatarsal phalangeal joint, resulting in stiffness, pain, and limitation in daily function. Surgery of HR is indicated in those who have failed a trial of non-operative management and is typically divided into joint-preserving (JP) and joint-sacrificing procedures. Cheilectomy is the most commonly practiced JP procedure, often done in conjunction with associated procedures for HR. Our paper aims to report the clinical outcomes after cheilectomy and cheilectomy done with subchondroplasty (SCP) performed for HR. Methods All patients who underwent cheilectomy for HR between 2017 and 2022 were identified and had their outcomes evaluated at the time of this review. The patients had their pre-operative radiographs and clinical and operative notes analyzed for the grading of HR. Functional outcomes were assessed with the use of the visual analog scale (VAS) and American Orthopaedic Foot and Ankle Society (AOFAS) scores, as well as comparing the pre-operative and post-operative degree of dorsiflexion of the affected first metatarsophalangeal joint. This study was approved by the SingHealth Institutional Review Board (IRB) Institution with approval number 2021/2629. Results A total of 19 patients and 20 feet were included in our study at a mean follow-up of 29.8 months. There was an increase in dorsiflexion of the first MTP joint by 27.2 degrees (p-value = <0.0001). Patients who underwent cheilectomy alone (Group 1) had a mean improvement in VAS scores of 5.46 (p-value = <0.0001). Patients who underwent SCP of the first metatarsal head along with cheilectomy (Group 2) had an improvement in VAS scores by 5.78 (p-value = 0.0007). There was a mean improvement in AOFAS scores of 25.6 (p-value = <0.0001) for patients in Group 1. Patients in Group 2 had a mean improvement in AOFAS scores of 31.0 (p-value = 0.0003). Conclusion Both cheilectomy and cheilectomy performed with SCP for HR show good outcomes at short-term follow-up (mean 29.8 months). Cheilectomy is a viable alternative to arthrodesis for the surgical treatment of HR even in patients with higher grades. The use of SCP should be further explored as an adjunct in the surgical treatment of HR.

Efficacy of Subchondroplasty in the Treatment of Pain Associated With Bone Marrow Lesions in the Osteoarthritic Knee

Background

Bone marrow lesions (BMLs) are common subchondral defects revealed by magnetic resonance imaging (MRI) in patients with osteoarthritis, often associated with pain and functional limitation. Subchondroplasty (SCP) is a relatively new technique in which bone substitute material (BSM) is injected inside BML areas to provide structural support to the subchondral bone, preventing its collapse and reducing pain.

Purpose/Hypothesis

The purpose of this study was to characterize changes in pain, functional and radiological outcomes, conversion to knee replacement, and complications after SCP. We hypothesized that ≥70% of patients would achieve a reduction in pain of ≥4 points on a numeric rating scale (NRS) at a 6-month follow-up after SCP.

Study Design

Case series; Level of evidence, 4.

Methods

Patients with symptomatic knee BMLs who underwent SCP were prospectively evaluated preoperatively and at 1, 6, 12, and 24 months postoperatively. Functional outcomes were measured with the NRS for pain, Knee Society Score (KSS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and International Knee Documentation Committee (IKDC) scores. Radiographs and MRI were performed preoperatively and at 6- and 12-month follow-ups to verify edema healing and changes in bone structure.

Results

A total of 50 patients were included in the study. The mean follow-up was 26 months (24-30 months). Compared with preoperative values, the mean NRS score decreased at every follow-up point (P < .0001 for all) and the IKDC, WOMAC, and KSS scores improved significantly at 6- and 12-month follow-ups. At 6 months postoperatively, 27 patients (54%) registered a reduction on the NRS of ≥4 points. Postoperative MRI revealed a hypointense zone surrounded by a hyperintense signal at the injection site. Standard radiography showed osteoarthritis grade worsening in 4 (8%) patients. Knee replacement was performed in 11 patients -in 7 patients due to the worsening or persistence of disabling symptoms and in 4 patients due to the progression of osteoarthritis. The leakage of BSM occurred in 6 patients without any clinical consequences during the study period.

Conclusion

About half of the study patients achieved a reduction in the NRS of 4 points at the 6-month follow-up after SCP.

Registration

NCT04905394 (ClinicalTrials.gov identifier).

Tissue Integration of Calcium Phosphate Compound after Subchondroplasty: 4-Year Follow-Up in a 76-Year-Old Female Patient

Subchondroplasty is a new minimally invasive surgical technique developed to treat bone marrow lesions (BML) and early osteoarthritis (OA). During the procedure, engineered calcium phosphate compound (CPC) is injected. It is claimed by the manufacturer that during the healing process, the CPC is replaced with new bone. The purpose of this study was to verify the replacement of CPC with new bone after subchondroplasty for the first time in humans. A 76-year old woman was referred for resistant medial knee pain. Standing radiographs showed varus knee OA and magnetic resonance imaging (MRI) revealed BML. She was treated with subchondroplasty of medial femoral condyle. Excellent relief of pain was achieved after procedure. Afterwards, the pain worsened, the radiographs confirmed the OA progression and the patient was treated with a total knee arthroplasty (TKA) 4 years after primary procedure. The resected bone was examined histologically and with micro-computed tomography (CT). Histologically, bone trabeculae of subcortical bone were embedded in the amorphous mass. However, no signs of CPC resorption and/or bone replacement have been found with micro-CT. In short term, excellent pain relief could be expected after the subchondroplasty procedure. However, there was no replacement of CPC with bone and the technique probably did not influence the natural process of knee OA.

Interventional Therapies for Osteoarthritis: An Update

Osteoarthritis (OA) is one of the most common diseases worldwide and is expected to increase in incidence as the age of the general population rises. Both oral medications, such as NSAIDs, and surgical treatments used for OA management have limitations. Demand is rising for minimally invasive techniques such as intraarticular injections and percutaneous interventions for use in place of or in conjunction with oral medications and surgical therapies, and the past 2 decades have seen a rapid expanse in both pharmacologic and nonpharmacologic minimally invasive OA treatments. Image guidance with fluoroscopy, CT, or ultrasound is often used in conjunction with these procedures to achieve precise treatment localization to achieve maximal therapeutic effect. The choice of modality used for image guidance is often influenced by clinician experience, patient characteristics, and equipment availability. This article reviews the mechanisms of action, contraindications, complications, and efficacy of conventional and developing minimally invasive OA treatments. The minimally invasive treatment options described in this Review include therapeutic injections such as antiinflammatory agents, viscosupplements, and biologics, as well as nonpharmacologic treatments of subchondroplasty, nerve ablation, genicular artery embolization, intraarticular pulsed radiofrequency therapy, and MRI-guided focused ultrasound therapy.

Mesenchymal stem cells for subchondral bone marrow lesions: From bench to bedside

Subchondral bone marrow lesions (BMLs) are areas of disease within subchondral bone that appear as T1 hypointense and T2 hyperintense ill-defined areas of bone marrow on magnetic resonance imaging. The most common bone marrow lesions include subchondral lesions related to osteoarthritis, osteochondral defects, and avascular necrosis. Emerging therapies include autologous biologic therapeutics, in particular mesenchymal stem cells (MSCs), to maintain and improve cartilage health; MSCs have become a potential treatment option for BMLs given the unmet need for disease modification. Active areas in the preclinical research of bone marrow lesions include the paracrine function of MSCs in pathways of angiogenesis and inflammation, and the use of bioactive scaffolds to optimize the environment for implanted MSCs by facilitating chondrogenesis and higher bone volumes. A review of the clinical data demonstrates improvements in pain and functional outcomes when patients with knee osteoarthritis were treated with MSCs, suggesting that BM-MSCs can be a safe and effective treatment for patients with painful knee osteoarthritis with or without bone marrow lesions. Preliminary data examining MSCs in osteochondral defects suggest they can be beneficial as a subchondral injection alone, or as a surgical augmentation. In patients with hip avascular necrosis, those with earlier stage disease have improved outcomes when core decompression is augmented with MSCs, whereas patients in later stages post-collapse have equivalent outcomes with or without MSC treatment. While the evidence for the use of MSCs in conditions with associated bone marrow lesions seems promising, there remains a need for continued investigation into this treatment as a viable treatment option.

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Common BMLs include osteoarthritis, osteochondral defects, and avascular necrosis.

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Patients with knee osteoarthritis treated with MSCs show improved pain and function.

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MSCs used as subchondral injection or surgical augmentation in osteochondral defects

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Improved outcomes of early hip avascular necrosis after core decompression with MSCs

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Additional preclinical and clinical evidence of MSCs as treatment for BMLs is needed.

Treatment of Subchondral Bone Marrow Edema with Intralesional Viscous Bone Cement in a Young, Active Patient: A Case Report

CASE

A 23-year-old male patient presented with symptomatic, high-grade medial tibial plateau bone marrow edema unresponsive to conservative treatment. After the injection of intralesional viscous bone cement, the patient had resolution of his symptoms and returned to running.

CONCLUSION

The use of intralesional viscous bone cement has grown in popularity for the treatment of bone marrow edema in individuals older than 40 years but is uncommon in younger individuals. This case demonstrates that intralesional viscous bone cement may be considered in the treatment of high-grade bone marrow edema in young, active patients who are unresponsive to extensive conservative management.

Bone in osteoarthritis: imaging and interventions

PURPOSE OF REVIEW

To review the recent literature on bone in osteoarthritis (OA), with a focus on imaging and intervention studies.

RECENT FINDINGS

Most studies focused on knee OA; hip and hand studies were uncommon. Bone shape studies demonstrated that shape changes precede radiographic OA, predict joint replacement, and have demonstrated high responsiveness. Novel quantitative 3D imaging markers (B-score) have better characterized OA severity, including preradiographic OA status. The addition of computerized tomography-derived 3D metrics has improved the prediction of hip joint replacement when compared to radiographs alone.Recent studies of bisphosphonates for knee OA have reported no benefits on pain or bone marrow lesion (BML) size. A meta-analysis on Vitamin D supplementation in knee OA suggested minimal symptom improvement and no benefits on the structure. Cathepsin K inhibition demonstrated reduction in OA bone change progression, but with no symptom benefit. Studies of injections of bone substitutes into BMLs (subchondroplasty) have generally been small and potential benefits remain unclear.

SUMMARY

Subchondral bone features are associated with pain, incidence and progression of OA. Recent studies have validated quantitative bone shape as a biomarker for OA trials. Trials of bone-targeted OA therapies have been disappointing although cathepsin K inhibition may slow structural progression.

Injections in the osteoarthritic knee: a review of current treatment options

Knee osteoarthritis is a degenerative condition characterized by progressive cartilage degradation, subchondral damage, and bone remodelling. Among the approaches implemented to achieve symptomatic and functional improvements, injection treatments have gained increasing attention due to the possibility of intra-articular delivery with reduced side effects compared to systemic therapies.

In addition to well-established treatment options such as hyaluronic acid (HA), cortico-steroids (CS) and oxygen-ozone therapy, many other promising products have been employed in the last decades such as polydeoxyribonucleotide (PDRN) and biologic agents such as platelet-rich plasma (PRP) and mesenchymal stem cells (MSCs). Moreover, ultrasound-guided intra-meniscal injection and X-ray-guided subchondral injection techniques have been introduced into clinical practice.

Even when not supported by high evidence consensus, intra-articular CS and HA injections have gained precise indications for symptomatic relief and clinical improvement in OA. Biological products are strongly supported by in vitro evidence but there is still a lack of robust clinical evidence. PRP and MSCs seem to relieve OA symptoms through a regulation of the joint homeostasis, even if their capability to restore articular cartilage is still to be proved in vivo.

Due to increasing interest in the subchondral bone pathology, subchondral injections have been developed with promising results in delaying joint replacement. Nevertheless, due to their recent development and the heterogeneity of the injected products (biologic agents or calcium phosphate), this approach still lacks strong enough evidence to be fully endorsed.

Combined biological treatments, nano-molecular approaches, monoclonal antibodies and ‘personalized’ target therapies are currently under development or under investigation with the aim of expanding our armamentarium against knee OA.

Cite this article: EFORT Open Rev 2021;6:501-509. DOI: 10.1302/2058-5241.6.210026