Cartilage Quality (dGEMRIC Index) Following Knee Joint Distraction or High Tibial Osteotomy

Abstract

Objective: High tibial osteotomy (HTO) and knee joint distraction (KJD) are treatments to unload the osteoarthritic (OA) joint with proven success in postponing a total knee arthroplasty (TKA). While both treatments demonstrate joint repair, there is limited information about the quality of the regenerated tissue. Therefore, the change in quality of the repaired cartilaginous tissue after KJD and HTO was studied using delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC).

Design: Forty patients (20 KJD and 20 HTO), treated for medial tibiofemoral OA, were included in this study. Radiographic outcomes, clinical characteristics, and cartilage quality were evaluated at baseline, and at 1- and 2-year follow-up.

Results: Two years after KJD treatment, clear clinical improvement was observed. Moreover, a statistically significant increased medial (Δ 0.99 mm), minimal (Δ 1.04 mm), and mean (Δ 0.68 mm) radiographic joint space width (JSW) was demonstrated. Likewise, medial (Δ 1.03 mm), minimal (Δ 0.72 mm), and mean (Δ 0.46 mm) JSW were statistically significantly increased on radiographs after HTO. There was on average no statistically significant change in dGEMRIC indices over two years and no difference between treatments. Yet there seemed to be a clinically relevant, positive relation between increase in cartilage quality and patients' experienced clinical benefit.

Conclusions: Treatment of knee OA by either HTO or KJD leads to clinical benefit, and an increase in cartilage thickness on weightbearing radiographs for over 2 years posttreatment. This cartilaginous tissue was on average not different from baseline, as determined by dGEMRIC, whereas changes in quality at the individual level correlated with clinical benefit.

Keywords: dGEMRIC; high tibial osteotomy; knee joint distraction; knee osteoarthritis.

Figure 1.

Inclusion flowchart. Patients considered for high tibial osteotomy (HTO) or total knee arthroplasty (TKP), included in either of the randomized trials (NL 35856.041.11 or NL 34296.041.10) were asked to participate in this extended imaging trial (NL 38442.041.11). Additional dGEMRIC imaging was performed at baseline and after 2 years for HTO patients, and at baseline, and after 1 and 2 years for knee joint distraction (KJD) patients.

Figure 2.

Posteroanterior radiographs of knee joint distraction (left) and high tibial osteotomy (right).

Figure 3.

Delineating anterior (a), central (c), and posterior (p) regions of interest (ROIs) of the medial (M) and lateral (L) tibia (T) and femur (F). Regions are separated at the most anterior and posterior horn of the meniscus (green arrowheads), the anterior regions reach until the most anterior part of the tibia plateau (orange arrows). The posterior tibial region is bounded at the most posterior part of the tibia plateau, while the posterior femoral regions encompass all visible cartilage (orange arrows). Six regions are delineated per slice, for 3 consecutive slices in both the lateral and femoral compartments.

Figure 4.

(A) Sagittal view of the lateral side of a tibiofemoral joint. (B) Automated in-house developed algorithm used to reconstruct a quantitative T1 map. The dGEMRIC index map is then superimposed onto the scan acquired for TI = 1650 ms. A color scale was used, representing the condition of the cartilage, ranging from degenerative (yellow) toward healthy (blue; low GAG content results in a low dGEMRIC index, and vice versa) (For interpretation of the references to colours in this figure legend, refer to the online version of this article).

Figure 5.

Change in WOMAC, VAS Pain, and medial/lateral/minimal/mean JSW, 1 year and 2 years after KJD or HTO. Visualized as mean change (± standard error of the mean) over 12 and 24 months, corrected for baseline. *Statistically significant (P < 0.05) difference over time within treatment. ^#Statistically significant (P < 0.05) difference in changes over time between treatments. WOMAC = Western Ontario and McMaster Universities Osteoarthritis Index; VAS = visual analogue scale; JSW = joint space width; KJD, knee joint distraction; HTO, high tibial osteotomy.