Michael A. Zacchilli, MD

The authors review current evidence for clinical outcomes of microfracture in the patellofemoral joint.  Concerns regarding MF’s longevity and potential impact on other techniques have recently damaged its reputation.  In contrast, other cartilage restoration surgeries are flourishing. Despite current trends dismissing microfracture’s value, it would be a mistake to overlook this important work.

The systematic review includes eight articles (174 patients aged 21 to 49.4 years) with patellofemoral microfracture (MF) of lesions between 1.3 cm² to 3.6 cm² at 12 to 72 months. The review demonstrates significant improvements in outcomes in all eight studies, 62% to 87% satisfaction rates, and better outcomes in younger patients (<40 years old).  One study showed higher satisfaction for lower grade lesions, but also treated partial thickness lesions. Comparisons between patellofemoral and tibiofemoral locations were contradictory. There was inadequate evidence regarding the effect of lesion size. One study demonstrated MF outcome declines at 18 and 36 months.

Placed in the context of our current evidence, this review provides an important foundation for future work. Despite advances, new technologies have at times failed to demonstrate significant clinical differences. Petri and colleagues (included in the review) showed no difference in Lysholm, Cincinnati or IKDC scores at 36 months between MF and MACI in the patellofemoral joint.¹ A recent level 2 cohort comparing patellar MACI and MF at 48 months showed higher 12 to 48 month MOCART scores with MACI, but no significant differences in pain or outcomes scores in 4 years with one exception (48 month Tegner). Further complicating matters, augmented MF shows promise: An in-press multicenter RCT reports superior outcomes for collagen-augmented MF vs. MF for 12- and 24-month MOCART score, VAS, and KOOS MCID rates (Kim and colleagues). In this context, the current review suggest it is too early to abandon MF as an option.

The limitation of this systematic review is primarily the lack of high-quality evidence: Half of the included studies (76 patients) are level 4. The exclusion of patients with concomitant patellar stabilization or offloading surgery refined but significantly restricted the study population. Given the reasonable clinical outcomes identified in our limited available literature, the study’s most important outcome may be to encourage the inclusion of patellofemoral MF in future high-level research.

Kim MS, et al.  Arthroscopy. 2019;doi:10.1016/j.arthro.2019.11.110.

Olivos Meza A, et al. Cartilage. 2019;doi:10.1177/1947603519835909.

Petri M, et al. J Orthop Sci.2013;18: 38-44.