Risk of Arthroplasty in Patients with Subchondral Insufficiency Fractures of the Knee: A Matched Study of the Implantable Shock Absorber using a Validated Predictive Model

Abstract

Subchondral insufficiency fractures of the knee (SIFK) can result in high rates of osteoarthritis and arthroplasty. The implantable shock absorber (ISA) implant is a titanium and polycarbonate urethane device which reduces the load on the medial compartment of the knee by acting as an extra-articular load absorber while preserving the joint itself. The purpose of this study was to evaluate whether partially unloading the knee with the ISA altered the likelihood of progression to arthroplasty utilizing a validated predictive risk model (SIFK score). A retrospective case-control (2:1) study was performed on patients with SIFK without any previous surgery and on those implanted with the ISA with the primary outcome being progression to arthroplasty compared with nonoperative treatment at 2 years. Baseline and final radiographs, as well as magnetic resonance imagings, were reviewed for the evaluation of meniscus or ligament injuries, insufficiency fractures, and subchondral edema. Patients from a prospective study were matched using the exact SIFK Score, a validated predictive score for progression to arthroplasty in patients with SIFK, to those who received the ISA implant. Kaplan–Meier analysis was conducted to assess survival. A total of 57 patients (38 controls:19 ISA) with a mean age of 60.6 years and 54% female were included. The SIFK score was matched exactly between cases and controls for all patients. The 2-year survival rate of 100% for the ISA group was significantly higher than the corresponding rate of 61% for the control group (p < 0.01). In ISA, 0% of the patients converted to arthroplasty at 2 years, and 5% (one patient) had hardware removal at 1 year. When stratified by risk, the ISA group did not have a significantly higher survival compared with low-risk (p = 0.3) or medium-risk (p = 0.2) controls, though it had a significantly higher survival for high-risk groups at 2 years (100 vs. 15%, p < 0.01). SIFK of the medial knee can lead to significant functional limitation and high rates of conversion to arthroplasty. Implants such as the ISA have the potential to alter the progression to arthroplasty in these patients, especially those at high risk.

Keywords

root tears - subchondral insufficiency fracture - SONK - SIFK - spontaneous osteonecrosis

• References

• 1 Houpt JB, Pritzker KP, Alpert B, Greyson ND, Gross AE. Natural history of spontaneous osteonecrosis of the knee (SONK): a review. Semin Arthritis Rheum 1983; 13 (02) 212-227
• 2 Ramnath RR, Kattapuram SV. MR appearance of SONK-like subchondral abnormalities in the adult knee: SONK redefined. Skeletal Radiol 2004; 33 (10) 575-581
• 3 Breer S, Oheim R, Krause M, Marshall RP, Amling M, Barvencik F. Spontaneous osteonecrosis of the knee (SONK). Knee Surg Sports Traumatol Arthrosc 2013; 21 (02) 340-345
• 4 Yamamoto T, Bullough PG. Spontaneous osteonecrosis of the knee: the result of subchondral insufficiency fracture. J Bone Joint Surg Am 2000; 82 (06) 858-866
• 5 Nelson FR, Craig J, Francois H, Azuh O, Oyetakin-White P, King B. Subchondral insufficiency fractures and spontaneous osteonecrosis of the knee may not be related to osteoporosis. Arch Osteoporos 2014; 9: 194
• 6 Yamagami R, Taketomi S, Inui H, Tahara K, Tanaka S. The role of medial meniscus posterior root tear and proximal tibial morphology in the development of spontaneous osteonecrosis and osteoarthritis of the knee. Knee 2017; 24 (02) 390-395
• 7 Yasuda T, Ota S, Fujita S, Onishi E, Iwaki K, Yamamoto H. Association between medial meniscus extrusion and spontaneous osteonecrosis of the knee. Int J Rheum Dis 2018; 21 (12) 2104-2111
• 8 Plett SK, Hackney LA, Heilmeier U. et al. Femoral condyle insufficiency fractures: associated clinical and morphological findings and impact on outcome. Skeletal Radiol 2015; 44 (12) 1785-1794
• 9 Pareek A, Parkes CW, Bernard C. et al. Spontaneous osteonecrosis/subchondral insufficiency fractures of the knee: high rates of conversion to surgical treatment and arthroplasty. J Bone Joint Surg Am 2020; 102 (09) 821-829
• 10 Pareek A, Parkes CW, Bernard CD, Abdel MP, Saris DBF, Krych AJ. The SIFK score: a validated predictive model for arthroplasty progression after subchondral insufficiency fractures of the knee. Knee Surg Sports Traumatol Arthrosc 2020; 28 (10) 3149-3155
• 11 Slynarski K, Walawski J, Smigielski R, van der Merwe W. Two-year results of the PHANTOM High Flex Trial: a single-arm study on the Atlas Unicompartmental Knee System load absorber in patients with medial compartment osteoarthritis of the knee. Clin Med Insights Arthritis Musculoskelet Disord 2019; 12: 1179544119877170
• 12 Slynarski K, Walawski J, Smigielski R, van der Merwe W. Feasibility of the Atlas Unicompartmental Knee System load absorber in improving pain relief and function in patients needing unloading of the medial compartment of the knee: 1-year follow-up of a Prospective, Multicenter, Single-Arm Pilot Study (PHANTOM High Flex Trial). Clin Med Insights Arthritis Musculoskelet Disord 2017; 10: 1179544117733446
• 13 Schoenfeld DA. Sample-size formula for the proportional-hazards regression model. Biometrics 1983; 39 (02) 499-503
• 14 Klein JP, Moeschberger ML. Survival analysis: techniques for censored and truncated data: Springer Science & Business Media; 2006
• 15 Bhatia S, LaPrade CM, Ellman MB, LaPrade RF. Meniscal root tears: significance, diagnosis, and treatment. Am J Sports Med 2014; 42 (12) 3016-3030
• 16 Hussain ZB, Chahla J, Mandelbaum BR. et al. The role of meniscal tears in spontaneous osteonecrosis of the knee: a systematic review of suspected etiology and a call to revisit nomenclature. Am J Sports Med 2019; 47 (02) 501-507
• 17 Petersen W, Ellermann A, Henning J. et al. Non-operative treatment of unicompartmental osteoarthritis of the knee: a prospective randomized trial with two different braces-ankle-foot orthosis versus knee unloader brace. Arch Orthop Trauma Surg 2019; 139 (02) 155-166
• 18 Briggs KK, Matheny LM, Steadman JR. Improvement in quality of life with use of an unloader knee brace in active patients with OA: a prospective cohort study. J Knee Surg 2012; 25 (05) 417-421
• 19 Day M, Wolf BR. Medial opening-wedge high tibial osteotomy for medial compartment arthrosis/overload. Clin Sports Med 2019; 38 (03) 331-349
• 20 Jacobi M, Wahl P, Jakob RP. Avoiding intraoperative complications in open-wedge high tibial valgus osteotomy: technical advancement. Knee Surg Sports Traumatol Arthrosc 2010; 18 (02) 200-203
• 21 van der Woude JAD, Wiegant K, van Heerwaarden RJ. et al. Knee joint distraction compared with high tibial osteotomy: a randomized controlled trial. Knee Surg Sports Traumatol Arthrosc 2017; 25 (03) 876-886
• 22 Jansen MP, Besselink NJ, van Heerwaarden RJ. et al. Knee Joint Distraction Compared with high tibial osteotomy and total knee arthroplasty: two-year clinical, radiographic, and biochemical marker outcomes of two randomized controlled trials. Cartilage 2019; (e-pub ahead of print)
• 23 Sihvonen R, Paavola M, Malmivaara A. et al; Finnish Degenerative Meniscal Lesion Study (FIDELITY) Group. Arthroscopic partial meniscectomy versus sham surgery for a degenerative meniscal tear. N Engl J Med 2013; 369 (26) 2515-2524
• 24 Katz JN, Brophy RH, Chaisson CE. et al. Surgery versus physical therapy for a meniscal tear and osteoarthritis. N Engl J Med 2013; 368 (18) 1675-1684
• 25 Harvey WF, Niu J, Zhang Y. et al. Knee alignment differences between Chinese and Caucasian subjects without osteoarthritis. Ann Rheum Dis 2008; 67 (11) 1524-1528