SLR - October 2020 - Janelle Maravelias
Tendon Regeneration After Partial-Thickness Peroneus Longus Tendon Harvesting Magnetic Resonance Imaging Evaluation and In Vivo Animal Study
Reference: Lee HW, Wang C, Bae TS, et al. Tendon Regeneration After Partial-Thickness Peroneus Longus Tendon Harvesting: Magnetic Resonance Imaging Evaluation and In Vivo Animal Study. Am J Sports Med. 2020;48(10):2499-2509. doi:10.1177/0363546520933628
Scientific Literature Review
Reviewed By: Janelle Maravelias, DPM, MS
Residency Program: St. Mary’s Medical Center – San Francisco, CA
Podiatric Relevance: It has been shown that the anterior half of the peroneus longus tendon (PLT) is an acceptable autograft source secondary to its strength and low donor site morbidity for various orthopedic ligament reconstruction procedures, however, this can leave the lateral foot and ankle disadvantaged without tendon regeneration. The purpose of the study was to investigate tendon regeneration on MRI after harvesting the anterior half of the peroneus longus tendon (AHPLT). The authors hypothesized quality of the partial-thickness harvested (PTH) tendon would be superior to regenerated tendon after full-thickness harvesting (FTH).
Methods: Twenty-one patients with no PLT pathology underwent AHPLT harvesting for various lower extremity ligament reconstructions. Twelve to 18 centimeters of AHPLT was harvested utilizing three small incisions and a tendon stripper. MRI was used to evaluate the PLT preoperatively, one week, and one year postoperatively. PTL regeneration was calculated accordingly. A separate in vivo animal study was preformed on 30 rats to compare quality of regenerated tendon after PTH and FTH of Achilles tendon. Quality of the regenerated tendons were compared 180 days after harvesting.
Results: MRI study – All 21 PLT cases demonstrated regeneration and no ruptures. The cross-sectional area of regenerated tendon was 92.6 percent and 84.5 percent at 4 centimeters and 9 centimeters proximal to distal fibula, respectively. In vivo animal study – macroscopically, regenerated tendons were formed on all specimens, however, regenerated PTH tendons were shiny, opaque, smooth and similar diameter as contralateral control whereas the regenerated FTH tendons were lusterless, dark, irregular surface and thicker diameter compared to contralateral control. Histological score was significantly different between PTH and FTH groups, with the PTH group showing tenocyte nuclei that were flat, spindle shaped and arranged in rows and FTH regenerated tendons showing wavy patterns, fiber fragmentation, round nuclei and vascular hyperplasia with infiltration of inflammatory cells. PTH group had more collagen type I and less collagen type III compared to FTH group. Ultimate tensile strength of regenerated tendon compared to contralateral control limbs was significantly higher in PTH group compared to FTH group (80.3 percent and 59 percent, respectively) and the stiffness of regenerated tendon compared to contralateral control limb was also significantly higher for PTH group compared to FTH group (74.8 percent and 56.1 percent, respectively).
Conclusions: The authors ultimately concluded that PLT would regenerate after partial thickness harvesting, with the regenerated tendon being nearly indistinguishable from the normal adjacent tendon. They also note the quality of the regenerated tendon during partial thickness harvesting was better quality than the full thickness harvesting group.
There were several limitations to the study including using the cross-sectional area of regenerated tendon on MRI inferring quality and performance of tendon and using the Achilles tendon in place of the PLT in the in vivo study. Even with these limitations, it is important to understand the quality and ability to regenerate following a partial or full-thickness tendon harvesting.