Presentation given by Dr Adnan Saithna, Professor of Orthopedic Surgery, at AAOS 2020, on the relationship between early post-operative extension deficit and subsequent risk of cyclops syndrome following ACL reconstruction

1. Extension Deficit in the Early Post-Operative Period is a Major Risk Factor for Cyclops
Syndrome: A Risk Factor Analysis in 3633 Patients Following ACL Reconstruction
Adnan Saithna, MD, FRCS(T&O)1,2
Professor of Orthopedic Surgery, Adjunct Clinical Faculty, Kansas City University
Jean-Romain Delaloye3, Florent Franck3, Jozef Murar3, Lionel Helfer3, Thais Dutra Vieira3 ,Charles Pioger3
and Bertrand Sonnery-Cottet3
1. Kansas City University of Medicine and Biosciences, Missouri, USA
2. Sano Orthopedics, Overland Park, KS, USA
3. Santy Clinic, FIFA Center for Medical Excellence, Lyon, France
Abstract: P0918

2. FINANCIAL DISCLOSURE
LIST ALL DISCLOSURES FROM PAST 12 MONTHS
Presenter: Adnan Saithna, MD
No Disclosures in the last 12 months
Co-author: Bertrand Sonnery-Cottet, MD
Arthrex: Consultant for Arthrex, Royalties from Arthrex

3. BACKGROUND/OBJECTIVE
• Re-operation rates after anterior cruciate ligament reconstruction (ACLR) are high, and
there is clearly a need to reduce them [1,2]
• One of the potential indications for re-operation is cyclops syndrome (loss of knee
extension secondary to the development of a nodule of fibrovascular proliferative
tissue that impinges in the intercondylar notch).
• Understanding factors that predispose to this syndrome may offer a pathway to
reducing its incidence.
• The objectives of this study were to evaluate the incidence and risk factors for cyclops
syndrome in a large series of patients undergoing ACL reconstruction. The study
hypothesis was that preservation of large ACL remnants would not increase the risk of
cyclops lesions.

4. METHODS AND MATERIALS
• Retrospective analysis of prospectively collected data was performed including all
patients who underwent primary ACL reconstruction with either Bone–patellar tendon–
bone (B-PT-B) or hamstring tendon (HT) autografts, between January 2011 to
December 2017.
• Intra-operatively, a remnant-sparing technique was used whenever possible. The ACL
remnant size remaining at the end of surgery was categorized as large if it exceeded
50% of the native ACL length.
• Physical examinations were conducted preoperatively and at the following
postoperative intervals: weeks 3 and 6 and months 3, 6, and 12.
• All patients who underwent re-operation for arthroscopic debridement of a symptomatic
cyclops lesion were identified and potential risk factors were analyzed in a multivariate
logistic regression.

5. RESULTS
• 3633 patients were included in the study. 65 (1.8%) underwent re-operation for
cyclops syndrome. The tables below report the differences between those who did,
and did not develop cyclops syndrome, with respect to patient demographics, and
intra-operative variables.

6. RESULTS OF MULTIVARIATE ANALYSIS
• After univariate analysis, the following factors reached the 25% threshold of correlation
with cyclops syndrome and were included in a multivariate analysis:
– knee extension deficit at 3 and/or 6 weeks postoperatively
– body mass index >25
– presence of bimeniscal lesions
• Neither the preservation of remnants nor their size were significant but they were also
included in the multivariate analysis because of their frequent citation in literature as a
potentially important risk factor.
• Of the factors included in multivariate analysis, only knee extension deficits at 3 and/or
6 weeks postoperatively were associated with a significant increase in the risk of
cyclops syndrome

7. CORRELATION BETWEEN EXTENSION DEFICIT AT 3 AND 6 WEEKS
POSTOPERATIVELY AND SUBSEQUENT CYCLOPS SYNDROME

8. DISCUSSION
• The main findings of this study were that 1.8% of patients developed cyclops
syndrome after ACL reconstruction and that extension deficit at 3 and 6 weeks
post-operatively was an important risk factor for its development.
• None of the other factors studied, including the preservation of large ACL
remnants, was a significant risk factor.
• It is of considerable interest to note that Gohil et al. previously reported that MRI
evaluation of patients with an extension deficit at two months postoperatively did
not demonstrate any structural lesion and imaging evidence of a cyclops lesion
only developed at considerably later time points. [3] The literature supports the
speculation that that early postoperative loss of extension could allow the
development of scar tissue in the intercondylar notch leading to cyclops syndrome
and therefore early rehabilitation should focus on regaining full extension.[4] The
current study indicates that full extension should be regained by 3 weeks post-
operatively, in order to minimize risk.

9. CONCLUSION
• In conclusion, preservation of large ACL remnants does not increase the risk of
cyclops syndrome after ACL reconstruction. The most important risk factor for
cyclops syndrome is failure to regain full extension in the early postoperative period.

10. REFERENCES
1. Hettrich CM, Dunn WR, Reinke EK; MOON Group; Spindler KP. The rate of
subsequent surgery and predictors after anterior cruciate ligament reconstruction:
two- and 6-year follow-up results from a multicenter cohort. Am J Sports Med.
2013;41(7):1534-1540.
2. Kartus J, Magnusson L, Stener S, et al. Complications following arthroscopic anterior
cruciate ligament reconstruction: a 2–5-year follow-up of 604 patients with special
emphasis on anterior knee pain. Knee Surg Sports Traumatol Arthrosc. 1999;7:2-8
3. Gohil S, Falconer TM, Breidahl W, Annear PO. Serial MRI and clinical assessment
of cyclops lesions. Knee Surg Sports Traumatol Arthrosc. 2014;22(5):1090-1096.
4. Pinto FG, Thaunat M, Sonnery-Cottet B, et al. Hamstring contracture after ACL
reconstruction is associated with an increased risk of cyclops syndrome. Orthop J
Sports Med. 2017;5(1):2325967116684121