Tendon regeneration and muscle hypotrophy after isolated Gracilis tendon harvesting - a pilot study

Abstract

Purpose: The gracilis tendon (GT) is a commonly used autologous graft in Orthopaedic surgery. The majority of information on knee function and outcomes after hamstring harvest is related to both semitendinosus and GT harvest. Little is known regarding isolated harvest of a GT. It was hypothesized that isolated GT harvest would lead to altered gait patterns (e.g. augmented anterior-posterior translation or rotation in the tibiofemoral joint) and consequently a higher prevalence of cartilage lesions and meniscal tears in knees. Methods: GT harvesting was performed on patients with chronic acromioclavicular joint instability without previous knee injuries or surgeries. MRI of both knees and thighs were performed. Knee MRI were evaluated using the Whole-Organ Magnetic Resonance Imaging Score (WORMS). Inter-and intraobserver reliabilities, cross-sectional areas of different muscles, fatty infiltration of the gracilis muscle (GM) and GT regeneration were evaluated. The contralateral limb served as reference. The observers were blinded towards the identity of the patients and the operatively treated side. Results: After a mean time of 44 months after surgery testing was performed on 12 patients. No significant side-toside differences were found using WORMS, although there was a trend towards increased cartilage lesions after GT harvest (median healthy knee 4.8 and GT harvested knee 7.8 p = 0.086). Inter-and intraobserver repeatability was high with 0.899 (95% confidence interval (CI) 0.708-0.960) and 0.988 (95% CI 0.973-0.995), respectively. A significant hypotrophy of the GM with a mean decrease of 25.3%, 18.4% and 16.9% occurred at 25% (p = 0.016), 50% (p = 0.007) and 75% (p = 0.002) of the length of the femur from distal. No compensatory hypertrophy of other thigh muscles or increased fatty infiltration of the GM was found. Tendon regeneration took place in eight out of 12 patients. In case of regeneration, the regenerated tendon inserted in a more proximal place. Conclusion: Isolated harvest of the GT for shoulder procedures did not affect knee MRI significantly indicating therefore in general suitable graft utilization for surgeries outside of the knee. GT regenerated in most patients with just a more proximal insertion and a hypotrophy of the muscle belly.

Knee flexion strength deficits correlate with distal extent of tendon regeneration after hamstring harvest. Preliminary data from an Ultrasound based classification

“…There is a variable rate of regeneration of the tendons, and the Semitendinosus may regenerate differently from the Gracilis, leading some authors to advocate harvest of one tendon alone, or partial harvesting of the Semitendinosus. 6,28 Nevertheless, whether regeneration happens or not is not the significant issue after ACL reconstruction; what is relevant is functional recovery for these young adults, many of whom are sportspersons. There is no doubt that functional deficits of varying degree do occur and prognosticating residual deficits and potential return to full activity or sport is the key point.…”

Morphology of proximal and distal human semitendinosus compartments and the effects of distal tendon harvesting for anterior cruciate ligament reconstruction

“…Finally, the ACLR surgical intervention induces secondary trauma at the knee joint and is thus more complex than regular tenotomy. However, slightly greater changes in ACSA are seen in the distal compared to proximal gracilis muscle when its distal tendon is harvested for shoulder reconstruction (Flies et al, 2020 ). Therefore, the results found in the present study are likely due to the ST tendon harvest for the ACLR procedure rather than post‐ACLR immobilization and disuse, but should be confirmed in future studies assessing ST compartment alterations after an ST tendon autograft has been used for reconstructing other lower (Cody et al, 2018 ; Stenroos & Brinck, 2020 ) and upper (Ranne et al, 2020 ; Virtanen et al, 2014 ) limb tendons.…”

Morphology of proximal and distal human semitendinosus compartments and the effects of distal tendon harvesting for anterior cruciate ligament reconstruction

“…Finally, the ACLR surgical intervention induces secondary trauma at the knee joint and is thus more complex than regular tenotomy. However, slightly greater changes in ACSA are seen in the distal compared to proximal gracilis muscle when its distal tendon is harvested for shoulder reconstruction (Flies et al ., 2020). Therefore, the results found in the present study are likely due to the ST tendon harvest for the ACLR procedure, rather than post-ACLR immobilization and disuse, but should be confirmed in future studies assessing ST compartment alterations after an ST tendon autograft has been used for reconstructing other lower (Cody et al ., 2018; Stenroos & Brinck, 2020) and upper (Virtanen et al ., 2014; Ranne et al ., 2020) limb tendons.…”