Introduction

Osteoarthritis (OA) of the knee is the leading indication for joint replacement surgery, with the incidence of OA in the US expected to rise to rise to 67 million by 2030¹. There is a need for earlier intervention procedures and therapies to slow the progression of OA and delay more invasive procedures.

Content

While the loss of articular cartilage is the hallmark pathological change in OA, there is evidence to suggest an important role of abnormal subchondral bone in the early stages of disease, such as bone marrow lesions. Bone marrow lesions (BML) were initially described as bone marrow edema due to the appearance as bright signal on fluid sensitive MRI sequences. However, histopathology of BMLs suggests that there is minimal true edema. Instead, findings show abnormal bone spicules with excessive fibrosis and extensive bony remodeling; essentially the pattern often seen after fatigue fractures in bone². Felson first explored the relationship between the presence of these lesion on MRI in knee osteoarthritis with pain symptoms and progression of OA³.

In another study, Wluka et al. performed a longitudinal cohort study to assess the relationship between the presence of a BML at baseline and change in cartilage defects and cartilage volume in healthy adults, without knee pain or a history of significant knee trauma. The study found that BMLs, present in healthy asymptomatic individuals with no history of significant knee pain or trauma, are associated with an increased risk of cartilage defect progression and loss of cartilage volume⁴. This suggests that either BMLs or a factor associated with their presence may be important as a target for preventive measures for the clinical sequelae associated with progression of cartilage damage and knee OA.
Current methods of treating patients with symptomatic knee osteoarthritis include non-pharmacological options, such as physical therapy and unloader bracing, pharmacological treatments including pain medication (NSAIDs, opioids and acetaminophens, etc.), and viscosupplementation or corticosteroid injections. For patients with mild to moderate knee pain, these techniques provide temporary (< 6 months) pain relief⁵. More invasive surgical options include arthroscopic debridement to total or unicompartmental knee arthroplasty. Total knee arthroplasty (TKA) is an end-stage surgical procedure with a high rate of success but requires in-patient surgery and several months recovery time. There is a clinical need for an intermediate safe and reliable technique which can provide sustained pain relief for patients with knee pain.

The Subchondroplasty (SCP) procedure was first described by Sharkey (2012) as a minimally invasive treatment option for painful bone marrow lesions, which preserves the native joint⁶. Previous publications on SCP include retrospective case studies and case examples^7,8. Cohen and Sharkey retrospectively reviewed 66 patients that underwent SCP for the treatment of bone defects associated with osteoarthritis of the knee and demonstrated and improvement in pain and function scores with 70% of patients avoiding arthroplasty through 2 years⁷. This summary will review 2 year outcomes and conversion rates from the first prospective study of SCP for the knee. It will also provide an overview of indications including other joints currently under study.

References

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Zanetti M, Bruder E, Romero J, Hodler J. Bone marrow edema pattern in osteoarthritic knees: correlation between MR imaging and histologic findings. Radiology. 2000;215(3):835-840.

Felson DT, Chaisson CE, Hill CL, et al. The association of bone marrow lesions with pain in knee osteoarthritis. Paper presented at: Annals Internal Medicine; 4/3/2001, 2001.

Wluka A, Wang Y, Davies-Tuck M, English D, Giles G, Cicuttini FM. Bone marrow lesions predict progression of cartilage defects and loss of cartilage volume in healthy middle-aged adults without knee pain over 2 yrs. Rheumatology. 2008;47(9):1392-1396.

Crawford DC, Miller LE, Block JE. Conservative management of symptomatic knee osteoarthritis: a flawed strategy? Orthopedic reviews. 2013;5(1).

Sharkey PF, Cohen SB, Leinberry CF, Parvizi J. Subchondral bone marrow lesions associated with knee osteoarthritis. American Journal of Orthopedics (Belle Mead, NJ). 2012;41(9):413-417.

Cohen SB, Sharkey PF. Subchondroplasty for Treating Bone Marrow Lesions. Knee Surg. 2016;29(7):555-563.

Nevalainen MT, Sharkey PF, Cohen SB, Roedl JB, Zoga AC, Morrison WB. MRI findings of subchondroplasty of the knee: a two-case report. Clinical imaging. 2016;40(2):241-243.