Introduction

Currently, localized (osteo)chondral lesions in the knee joint are treated using several surgical treatment options. When more advanced cartilage degeneration exists, there are fewer options. When conservative treatment fails and cartilage degeneration evolves to osteoarthritis (OA), often a total knee arthroplasty (TKA) is the final solution. While TKA is a widely accepted intervention for end-stage knee OA, it poses a major healthcare burden when applied to young patients, since they have a higher risk of needing a costly and less effective revision surgery later in life.

Therefore, there is more and more interest in knee joint preserving treatments for OA. For example, an osteotomy is indicated if there is a leg malalignment and unicompartimental OA. The affected part is unloaded after the osteotomy. This treatment has been proven successful if applied with the right indication. Currently, there seems to be a revival of this elegant treatment, which has been described over 100 years. However, if there is no malalignment, of multicompartmental OA, an osteotomy is not a suitable option.

Content

Knee joint distraction (KJD) is anotherjoint-preserving treatment for knee OA for these younger patients. The concept of this treatment is that the knee joint is temporarily unloaded by separating the tibia and femur, using an external fixation frame.

Joint distraction has been applied at the ankle joint since the 90s with great success. Several clinical studies showed a relevant reduction of pain and improvement of function in patients with severe ankle OA for a period over seven years.¹These interesting results convinced our group to start treating young patients suffering from severe knee OA with joint distraction as well.

In an open prospective study between 2006 and 2008, twenty knee OA patients below the age of 60 indicated for TKA were treated for eight weeks with KJD.²These patients showed long-term, in the first two years progressive, significant clinical benefit as well as cartilage tissue regeneration. Over three quarters could postpone the TKA for over five years³and half of the patients was still without prosthesis nine years after treatment.⁴After this trial, the distraction period was shortened to six weeks, as this was considered to be sufficient. Between 2011 and 2014, the six-week KJD was studied in comparison to high tibial osteotomy or TKA in two separate randomized controlled trials.^5,6In both trials combined, 39 KJD patients gained significant clinical and structural progressive benefit in the first year, which was shown to be maintained up to at least two years after treatment.⁷Both trials demonstrated that KJD was non-inferior to the alternative treatment. The exact working mechanism of KJD is not unraveled. A recent clinical study demonstrated that the composition (biomarkers/growth factors) of the synovial fluid changes during the distraction period, which might help in the understanding of the working mechanism.⁸

Since 2014, KJD is offered as regular care treatment in a limited number of Dutch hospitals for knee OA patients under the age of 65. Often when a new treatment proceeds from clinical trial to regular care, pre-treatment patient characteristics broaden and treatment outcome weakens. As such, treatment and surgery details, baseline characteristics and treatment efficacy of KJD in regular care were compared with clinical trial conditions. This study showed that the 84 patients treated with KJD in regular care between 2014 and 2018 had in general the same characteristics as the patients included in clinical trials the years before.⁹Also, complications of treatment were comparable between patients treated in regular care and those treated in trials. Moreover, in case of available follow-up data no difference in clinical response at one year was observed either.

All in all, KJD is a promising surgical treatment for young patients suffering from end stage knee OA. The treatment can decrease pain and delay the need for TKA.

References

1. Prolonged clinical benefit from joints distraction in the treatment of ankle osteoarthritis. Ploegmaker JJ, van Roermund PM, van Melkebeek J, Lammers J, Bijlsma JW, Lafeber FPJG, Marijnissen AC. Osteoarthritis&Cartilage 2005 Jul;13(7):582-588.

2. Five-year follow-up of knee joint distraction: clinical benefit and cartilaginous tissue repair in an open uncontrolled prospective study. van der Woude JAD, Wiegant K, van Roermund PM, Intema F, Custers RJH, Eckstein F, van Laar JM, Mastbergen SC, Lafeber FPJG. Cartilage 2017 Jul;8(3):263-271.

3. Initial tissue repair predicts long-term clinical success of knee joint distraction as treatment for knee osteoarthritis. Jansen MP, van der Weiden GS, van Roermund PM, Custers RJH, Mastbergen SC, Lafeber FPJG. Osteoarthritis&Cartilage 2018 Dec;26(12):1604-1608.

4. Six weeks of continuous joint distraction appears sufficient for clinical benefit and cartilaginous tissue repair in the treatment of knee osteoarthritis. van der Woude JA, van Heerwaarden RJ, Spruijt S, Eckstein F, Maschek S, van Roermund PM, Custers RJH, van Spil WE, Mastbergen SC, Lafeber FPJG. Knee 2016 Oct;23(5):785-791.

5. Knee joint distraction compared with high tibial osteotomy: a randomized controlled trial. van der Woude JAD, Wiegant K, van Heerwaarden RJ, Spruijt S, van Roermund PM, Custers RJH, Mastbergen SC, Lafeber FPJG. Knee Surg Sports Traumatol Arthrosc. 2017 Mar;25(3):876-886.

6. Knee joint distraction compared with total knee arthroplasty: a randomized controlled trial. van der Woude JAD, Wiegant K, van Heerwaarden RJ, Spruijt S, Emans PJ, Mastbergen SC, Lafeber FPJG. Bone Joint J. 2017 Jan;99-B(1):51-58.

7. Knee joint distraction compared with high tibial osteotomy and total knee arthroplasty: two-year clinical, radiographic and biochemical marker outcome of two randomized controlled trials. Jansen MP, Besselink NJ, van Heerwaarden RJ, Custers RJH, Emans PJ, Spruijt S, Mastbergen SC, Lafeber FPJG. Cartilage. 2019 Feb13:2947603519828432. Doi:10.1177/1947603519828432.

8. Analysis of proteins in the synovial fluid during joint distraction: unravelling mechano-sensitive pathways that drive intrinsic cartilage repair? Watt FE, Hamid B, Garriga C, Hrusecka R, Custers RJH, Lafeber FPJG, Mastbergen SC, Vincent TL. Osteoarthritis&Cartilage Volume 26, Supplement 1, April 2018, Pages S17-S18.

9. Knee joint distraction as standard of care treatment for knee osteoarthritis: a comparison with clinical trial patients. Jansen MP, Mastbergen SC, van Empelen MD, Kester EC, Lafeber FPJG, Custers RJH. Osteoarthritis&Cartilage Volume 27, Supplement 1, April 2019, Pages S515-S516.

Acknowledgments

Thanks to the Department of Rheumatology&Clinical Immunology (University Medical Center Utrecht, The Netherlands) for the collaboration in the knee joint distraction work.