Question:
In children with osteochondritis dissecans (OCD) injuries of the knee, is osteochondral autologous transplantation (OAT) more effective than microfracture?
Design:
Randomized (allocation concealment unclear), blinded (assessor of magnetic resonance imaging [MRI] findings) controlled trial with 4-year follow-up.
Setting:
A university hospital in Kaunas, Lithuania.
Patients:
50 children <18 years of age (mean age, 14.3 y; 56% boys) with a single International Cartilage Repair Society (ICRS) grade 3 to 4 OCD lesion between 2 and 4 cm2 in a stable knee were included. All patients had not improved after 6 months of conservative treatment. 47 patients (94%) completed follow-up.
Intervention:
Patients were allocated to OAT (n = 25) or microfracture (n = 25). For all patients, residual fibrotic tissue of subchondral bone was removed from the defect. For the OAT procedure, the donor transplant was harvested with a larger (0.1-mm) cylinder and the lesion was carved out with a smaller cylinder. 5 and 6-mm plugs from the lateral or medial margin of the femoral trochlea were placed at the same level as the healthy cartilage, as close together as possible. The joint trough was moved through a full range of movement to check for stable and correct placement of the plugs. For the microfracture procedure, an arthroscopic awl made multiple holes (2 to 4 mm wide) in the exposed subchondral bone plate, as close together as possible. Patients in both groups received prophylactic antibiotics at the time of surgery and at 6 and 12 hours after surgery and followed an identical rehabilitation program with the goal of full weight-bearing by 6 weeks.
Main outcome measures:
The outcomes of interest were ICRS repair grade score (score range: 1 = excellent, 2 = good, 3 = fair, and 4 = poor), return to preinjury activity level, and MRI evaluation.
Main results:
Both the OAT and microfracture groups improved in ICRS scores from baseline. More patients in the OAT group maintained excellent or good results than did patients in the microfracture group, but the differences were not significant (Table). More patients in the OAT group achieved the preinjury activity level than did patients in the microfracture group (Table). At 18.2 months after surgery, MRI showed excellent or good repairs in more patients who received OAT than in patients who received microfracture (Table).
Conclusion:
In children with OCD injuries of the knee, OAT was superior to microfracture repair.
The treatment of advanced OCD lesions in children is controversial. In those patients in whom the fragment is still partially attached or, if detached, has good cartilage and bone, fixation to the injury site has been considered the best treatment. However, if no salvageable fragment exists, the options are limited. Two of the main treatments are microfracture and osteochondral autograft placement (mosaicplasty). Other treatments include autogenous cartilage cell implantation and allograft osteochondral transplantation.
The study by Gudas and colleagues included patients who were similar with respect to key baseline variables, including age, sex, ICRS scores, and lesion size and location. Twenty-five patients received microfracture and twenty-five received osteoarticular transfer system (OATS; Arthrex) type mosaicplasty. At a mean follow-up of more than four years with only a 6% drop out rate, the OAT group did substantially better on several subjective and objective measures than did the microfracture group.
The magnetic resonance imaging assessment was performed a mean of eighteen months postoperatively, so there is no long-term radiographic assessment of these patients. Furthermore, the "second look" arthroscopies were done only for those who had continued symptoms after the index procedure and this is an obvious bias.
Although this study does not provide evidence about how to treat small OCD lesions (<2 cm2), in adolescents with larger OCD lesions, mosaicplasty (in this case the OAT procedure) should be performed preferentially to microfracture.