Introduction
More than 600,000 rotator cuff related procedures are performed in the US each year11. Studies have indicated that the prevalence of rotator cuff tears may exceed 50% in individuals above 65 years of age and the rate of tears significantly increases with age12. Twenty to 50% of these tears may become symptomatic over time13, 14, 15.
Both arthroscopic and open repair procedures have shown inconsistent success rates. Re-tears appear most frequently in the first 3 months after surgery and have been observed in 13 – 94% at 1 and 2-year follow-up16, 17, 18, 19. Many re-tears revert to their preoperative size18. The reason for re-tears is multifactorial. Successful tendon healing has been reported to be as low as 30%20.
To improve the healing response, biological augmentation of the index procedure through mesenchymal stem cell stimulation was introduced by Snyder and Burns in 200921.
The concept is based on microfracture of the greater tuberosity with the intent of bringing bone marrow elements to the repair site.
The authors compared clinical and imaging outcomes after arthroscopic rotator cuff repair with and without microfracture and noted an improved healing rate in large supraspinatus and infraspinatus tears21.
In a prospective randomised clinical trial with twenty eight months follow-up, Milano et al. compared full thickness rotator cuff repairs with and without microfracture of the footprint and reconfirmed a significantly greater healing rate in the microfracture group for large tears 20.
Nanofracture in Rotator Cuff Repair
Recent insight into the limitations of microfracture and drilling has opened-up new treatment pathways for mesenchymal stem cell stimulation5, 6. Smaller and deeper holes produced in the bone via Nanofracture allow for an increased biological response.
Iban et al reports that adding NanoFx at the footprint during an isolated supraspinatus repair lowers re-tear rate by 50% at 12-months follow-up.
This is due to improved healing at the footprint22.
In addition, recent biomechanical results demonstrated that augmentation with Nanofracture neither weakened the bone/suture anchor interface nor did it decrease the ultimate load to failure of the rotator cuff repair. The authors concluded that subchondral bone needling may be an excellent augment to rotator cuff repair23.
Nanofracture introduces a new level of standardisation and optimisation in subchondral mesenchymal stem cell stimulation.
The smaller diameter improves the stability of the cuff footprint when compared to larger microfracture channels and may yield higher repair rates through deeper, uncompressed trabecular channels
Microfracture
Microfracture: trabecular wall thickness and density increased by apparent bone compression; limited trabecular channel access; channel borders with non-anatomic regularity; microfracture channel margins: dense, compressed bone deposit (right)
Nanofracture (NanoFx)
Nanofracture: trabecular wall thickness and density appears normal; large number of open trabecular channels; anatomic irregularity of trabecular channel borders intact; nanofracture channel margins: course and fragmented trabecular bone deposits (right)
closed trabecular channels, microCT comparison: Axial (top) Sagittal (bottom)
open trabecular channels
12 Mall NA, Lee AS, Chahal J, et al. An evidence-based examination of the epidemiology and outcome of traumatic rotator cuff tears. Arthroscopy 29:366-376,2011
13 Moosmayer S, Tariq R, Stiris M, et al. The natural history of asymptomatic rotator cuff tears. J Bone Joint Surg 2013;95:1249-1255.
14 Mall NA, Kim HM, Keener JD, et al. Symptomatic progression of asymptomatic rotator cuff tears. J Bone Joint Surg 2010;92:2623-2633.
15 Yamaguchi K, Tetro M, Balm O, et al. Natural history of asymptomatic rotator cuff tears: a longitudinal analysis of asymptomatic tears detected sonographically. J Shoulder Elbow Surg 2001;10(3): 199-203.
16 Miller BS, Downie BK, Kohen RB et al. When do rotator cuff repairs fail? Serial ultrasound examination after arthroscopic repair of large and massive rotator cuff tears. AJSM 2011;39(10): 2064-2070.
17 Bishop J, Klepps S, Bird J, et al. Cuff integrity after arthroscopic versus open rotator cuff repair: A prospective study. J Shoulder Elbow Surg 2006:15:290-299.
18 Galatz LM, Ball CM, Teefey SA, et al. The outcome and repair integrity of completely arthroscopically repaired large and massive rotator cuff tears. J Bone Joint Surg 2004;86A: 219-224.
19 Kim S-J, Kim S-H, Lee S-K, et al. Arthroscopic repair of massive contracted rotator cuff tears: aggressive release with anterior and posterior interval slides do not improve cuff healing and integrity. J Bone Joint Surg 2013;95A:1482-1488.
20 Milano G, Saccoanno MF, Careri S, et al. Efficacy of marrow-stimulating technique in arthroscopic cuff repair: A prospective randomized study. Arthroscopy 201329:802-810.
21 Snyder SJ, Burns J. Rotator cuff healing and the bone marrow “Crimson Duvet” from clinical observations to science. Tech Should Surg 2009;10: 130—137
22 Ibán M A R, et al. Footprint preparation with nanofractures in a supraspinatus repair cuts in half the re-tear rate at 1-year follow-up. A randomised controlled trial. Knee Surg Sports Traumatol Arthroscopy
23 Aspey B, Poage C, Ostrander R, Roth CA. Effect of Subchondral Bone Needling on Suture Anchor Pull Out Strength: A Cadaveric Study. EC Orthopaedics 4.6 (2016): 641-652.
