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Intraoperative repair for iatrogenic MCL tear due to medial pie-crusting in TKA yields satisfactory mid-term outcomes



This study aimed to assess the rate of iatrogenic mid-substance superficial medial collateral ligament (sMCL) tear due to the medial pie-crusting technique during varus deformity total knee arthroplasty and compare the knee society score (KSS), range of motion (ROM), and instability rate of the repaired group to the control group with intact sMCL.


For this retrospective series of prospectively collected data, the multiple needle puncturing technique was performed for 653 out of the 1768 knees during algorithmic medial soft-tissue release. Iatrogenic tear was observed in 35 knees (5%); hence, repair with running locking nonabsorbable braided suture was performed. Patients were visited and reviewed both clinically and radiographically at 6 weeks, 3 months, 6 months, 12 months, and annually thereafter. Chi-square, ANOVA, Mann–Whitney, independent and paired t test were used to analyze the variables. P value < 0.05 was considered statistically significant.


85% of the repaired sMCL had stable joints with a mean KSS of 88 ± 3 and a mean ROM of 103 ± 11 degrees (°). The other five patients (15%) with mean KSS of 40 ± 8 and mean ROM of 81° ± 5° had an instability and needed to undergo a revision surgery. The control group had a mean KSS of 86 ± 15 and mean ROM of 107° ± 8°; however, 7 knees had an instability and needed a revision surgery. No significant difference was observed in terms of KSS (P = 0.86) and ROM (P = 0.64) between the control and repaired groups.


The mid-substance sMCL tear is an important intraoperative complication of medial pie-crusting. Repairing this iatrogenic tear with nonabsorbable suture had satisfying clinical outcomes regarding the postoperative knee ROM and KSS in comparison to the control group. However, there is a chance of failure, which should be perceived by the surgeons.

Level of evidence

Therapeutic studies, investigating the results of treatment, Level III.

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Availability of data and material

All of the data will be available for secondary analysis in necessary cases from the corresponding author through email address.


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The authors express their gratitude toward Mr. Amirsalar Moazen Safaei for his kind support during the project.



Author information




Conceptualization: MM, ES, MPA, HC, AS. Data curation: MM, ES, MPA, HC, AS. Formal analysis: ES, AS. Funding acquisition: MM, MPA, HC. Investigation: MM, ES, MPA, HC, AS. Methodology: MM, ES, MPA, HC, AS. Project administration: MM, ES, MPA, HC, AS. Resources: MM, MPA, HC. Software: ES, AS. Supervision: MM, MPA, HC. Validation: MM, ES, MPA, HC, AS. Visualization: MM, MPA, HC. Writing—original draft: MM, ES, MPA, HC, AS. Writing—review and editing: MM, ES, MPA, HC, AS.

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Correspondence to Mohammadreza Piri Ardakani.

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The authors declare no potential conflict of interest.

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All procedures performed in this study were in accordance with the ethical standards of the institutional and national research committee and with 1964 Helsinki declarations and its later amendments. The study commenced after receiving its ethical approval from the institutional review board of the Isfahan University of Medical Sciences with the registration number of "IR.MUI.RESEARCH.REC.1398.307". Written informed consent was obtained from all of the patients before the surgery.

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Motififard, M., Sheikhbahaei, E., Piri Ardakani, M. et al. Intraoperative repair for iatrogenic MCL tear due to medial pie-crusting in TKA yields satisfactory mid-term outcomes. Knee Surg Sports Traumatol Arthrosc (2020).

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  • Total knee replacement
  • Arthroplasty
  • Medial collateral ligament
  • Instability
  • Pie-crusting