Knee microfracture surgery is a common arthroscopic procedure where an awl (a sharp pointed tool) is pushed into the bone where the protective knee cartilage has worn away. The small holes made by the awl are called  microfractures. The goal of this surgery is to build new cartilage.

Surgical Cartilage treatment strategies are characterized as:

  • Chondroplasty, a procedure that shaves down or smooths out of cartilage.
  • Debridement (power washing the the knee cartilage),
  • Microfracture,
  • Transplantation autologous chondrocyte implantation [ACI], osteochondral autograft [OAT], and osteochondral allograft [OCA]).

In December 2023, researchers (1) at New York University also suggested: “numerous cartilage restoration techniques have proven to be effective in the treatment of articular cartilage defects. ” However, “the clinical benefits of microfracture are short-lived, which has led to the use of alternative procedures. Rehabilitation protocols are not standardized, but emphasis has been placed on bracing, weightbearing, early continuous passive range of motion, and strengthening to improve function. . . in appropriately selected patients, cartilage restoration procedures after articular cartilage injury result in favorable patient-reported clinical outcomes and high rates of return to play. While studies emphasize the critical role that rehabilitation plays with respect to outcomes after surgery, there are substantial inconsistencies in protocols across techniques.”

A February 2024 study (2) also compared  autologous chondrocyte implantation (ACI) and arthroscopic debridement (AD) in symptomatic, isolated cartilage injuries.

  • Twenty-eight patients were included and randomized to autologous chondrocyte implantation (ACI) or arthroscopic debridement and followed for 2 years.
  • There was a statistically significant and clinically meaningful improvement in patient-reported outcome measures from baseline to 2 years in both groups.
  • The improvement from baseline to final follow-up arthroscopic debridement (AD) compared with the autologous chondrocyte implantation (ACI) , but this difference was not statistically significant. significantly greater scores in the AD group for several KOOS subscales at several time points, including KOOS QoL, KOOS pain, and KOOS sport and recreation at 2 years.

Conclusions: This study indicates that arthroscopic debridement (AD) followed by supervised physiotherapy is equal to or better than autologous chondrocyte implantation (ACI) followed by supervised physiotherapy in patients with isolated cartilage lesions.

Autologous chondrocyte transplantation

In an October 2022 study, (3) doctors examined postoperative complications and associated risk factors for failure following autologous chondrocyte transplantation as well as its long-term survival and clinical function. The doctors hypothesized that “autologous chondrocyte transplantation is a safe technique for cartilage repair with a low incidence of postoperative complications and rare rates of revision surgery combined with a high long-term survival and good to excellent clinical outcome in long-term-follow-up.” This is what they found:

  • Postoperatively, 8% of patients had complications (4% bleeding, 2% arthrofibrosis, 2% infection)
  • 7% of patients needed revision surgery.
  • 12% of patients had a prolonged deficit in range of motion, that did not require revision surgery.
  • Patients demonstrated good patient reported long-term outcomes 9-15 years after the surgery.
  • Survival rates were 88% at 9 years, 85% at 11 years, and 85% at 13 years after the surgery.

The study indicates “autologous chondrocyte transplantation is an “effective treatment option for femorotibial- as well as patellofemoral cartilage defects with a high long-term survival and low conversion rate as well as good long-term results regarding knee function and satisfaction. Postoperative complications needing revision surgery are rare.”

References

1 Triana J, Li ZI, Rao N, Kingery MT, Strauss EJ. Return to Play After Knee Articular Cartilage Restoration: Surgical Options, Rehabilitation Protocols, and Performance Outcomes. Current Reviews in Musculoskeletal Medicine. 2023 Dec;16(12):575-86.
2 Randsborg PH, Brinchmann JE, Owesen C, Engebretsen L, Birkenes T, Hanvold HA, Benth JŠ, Årøen A. Autologous Chondrocyte Implantation Is Not Better Than Arthroscopic Debridement for the Treatment of Symptomatic Cartilage Lesions of the Knee: Two-Year Results From a Randomized-Controlled Trial. Arthroscopy, Sports Medicine, and Rehabilitation. 2024 Apr 1;6(2):100909.
3 Ehmann YJ, Esser T, Seyam A, Rupp MC, Mehl J, Siebenlist S, Imhoff AB, Minzlaff P. Low postoperative complication rate with high survival rate and good clinical outcome 9 years after autologous chondrocyte transplantation of the knee joint. Archives of Orthopaedic and Trauma Surgery. 2023 May;143(5):2665-74.