2017 ISAKOS Biennial Congress ePoster #1034

 

Pretibial Cyst Formation after ACL Reconstruction. A Series of 14 Cases with Different Etiologies

Juan Pablo Zicaro, MD, Olivos, Buenos Aires ARGENTINA
Matias Costa-Paz, MD, PhD., Buenos Aires, Buenos Aires ARGENTINA
Maximiliano Ranalletta, MD, Buenos Aires, Buenos Aires ARGENTINA
Carlos H. Yacuzzi, MD, Buenos Aires, BA ARGENTINA

Hospital Italiano de Buenos Aires, Buenos Aires, ARGENTINA

FDA Status Cleared

Summary

Pretibial cyst after ACL reconstruction is a rare complication. The purpose of this study was to analyze 14 patients following this complication. We believe the cysts to be multifactorial. In this series the tibial graft fixations were bioabsorbable and titanium screws. In 4 cases no tibial screw was used. None was associated to graft loosening.

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Abstract

Introduction

Among complications following ACL reconstruction, the formation of a pre-tibial cyst in the site of the tibial tunnel is very rare and might happen even years after surgery. The purpose of this study was to analyze 14 patients with tibial synovial cyst after ACL reconstruction.

Material And Methods

We retrospectively evaluated patients operated between 2008 and 2016. The inclusion criteria were patients operated for ACL reconstruction, who developed an extra-articular cyst at the tibial tunnel level. For recurrence evaluation, patients with less than one year follow-up were excluded. A pre and postoperative clinical and radiological evaluation was performed.
We analyzed the graft selection and surgical technique for ACL reconstruction, the time between primary surgery and the onset of symptoms and the clinical presentation. A pre and postoperative radiological evaluation was performed for every patient. Surgical technique for cyst excision, histological analysis and culture results where also analyzed. The recurrence rate was evaluated at final follow-up

Results

Nine patients were male, with an average age of 38 years. The average follow-up was of 35 months. All ACL reconstructions were performed using hamstring graft and a trans-tibial technique. Tibial fixation was a biodegradable screw in 9 patients, three of them associated with a staple. In four patients hamstring tibial insertion was left in situ with an open stripper and fixed in the tibia using non-absorbable Ethibond 2 sutures. The average time between primary ACL surgery and onset of the cyst was 29 months. All patients presented a palpable tumor at proximal tibia and a stable knee. The cyst size varied between 1.1 and 3 cm. In all cases, Rx and MRI could appreciate a widening of the tibial tunnel, though no articular communication could be confirmed.
The arthroscopic evaluation revealed no graft loosening. All cysts were approached through the previous tibial incision and staples or screws where removed. In all cases curettage was performed to the tibial tunnel walls, filling the space with cancellous bone in 7 of them (5 obtained from proximal tibia and 2 from the lateral femur condyle). Pathological anatomy reported 14 synovial cysts, 5 associated with remaining suture. No infection was informed.
At final follow-up, 13 of 14 patients returned to normal activities with no pain or recurrence. One patient required three open surgeries to achieve definitive treatment using bone allograft chips to fill the tibial tunnel. Despite the tunnel widening, no graft loosening was observed.

Discussion

Although most authors attempt to define an etiology for this complication, there is not enough evidence to support a unique conclusion. It has been traditionally associated with a foreign-body reaction. Though we believe the etiology to be multifactorial, cysts can be defined as communicating or non-communicating. If patients present with an onset of pain, surgical resection is indicated. When no articular communication is suspected, cyst resection and hardware removal might be sufficient. Otherwise, treatment must include debridement, hardware removal and local bone grafting. In case of a recurrence, aggressive curettage and extensive bone grafting is recommended. None of the patients revealed signs of instability.