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Arch Orthop Trauma Surg (2014) 134:829–834DOI 10.1007/s00402-014-1988-6

ArThrOScOpy AnD SpOrTS MeDIcIne

Early postoperative transtibial articular fistula formation after anterior cruciate ligament reconstruction: a review of three cases

J. Díaz Heredia · M. A. Ruiz Iban · R. Cuéllar Gutiérrez · R. Ruiz Diaz · I. Cebreiro Martinez del Val · L. Turrion Merino

received: 30 October 2013 / published online: 12 April 2014 © Springer-Verlag Berlin heidelberg 2014

treatment is required, and some delay in the rehabilitation routine is required, but the final outcome is not affected.

Keywords Anterior cruciate ligament reconstruction · Tibial cyst · Fistula · postoperative · complication

Introduction

Anterior cruciate ligament (AcL) reconstruction is the most frequent major arthroscopic procedure performed in the knee [1]. Around 300,000 AcL reconstructions are performed annually in the United States [2]. The overall results after primary AcL reconstruction are generally satisfying [3] and the procedure has low morbidity and few complications [3]. The most frequently reported complications are persistent pain, extension lag or alterations of cutaneous sensitivity [4]. Other complications, such as infection or deep venous thrombosis, are less prevalent but more severe [5–7]. pretib-ial cyst formation is an uncommon complication that usually appears years after an AcL reconstruction. cases have been described using different surgical techniques, grafts [5–11] and tibial fixation methods [5–7]. It is either discovered inci-dentally on MrI or clinically as pretibial swelling or a pal-pable mass with or without pain. no organisms or evidence of infection have been found in any of the available reports [12]. The aetiology is controversial and probably is related to different pathophysiological mechanisms [13, 14].

The purpose of this case report is to present three patients with an early postoperative transtibial articular fis-tula formation through the tibial tunnel after an AcL recon-struction procedure. These cases presented two distinct clinical patterns: either as a pretibial cyst or as persistent wound drainage. The aetiology and treatment options are also discussed.

Abstract Introduction This is a retrospective case report of three cases with an early postoperative transtibial fistula after anterior cruciate ligament reconstruction (AcL).Materials and methods The patients had undergone AcL reconstruction and complained of fluid drainage through the not-healed wound or swelling localized on the antero-medial aspect of the ipsilateral proximal tibia during the early postoperative. Magnetic resonance imaging showed a multilocular fluid-filled cyst arising from the distal hole of the tibial bone tunnel. Open resection of the fistula and the cyst was performed in all cases and communica-tion between the tibial tunnel and the joint space was con-firmed. During revision surgery the distal hole of the tibial tunnel was covered with a fascio-periosteal flap.Results All wounds healed without complications. There was no recurrence of drainage or cyst formation. At 2 years follow-up the knee function was normal and was not affected by the complication in any of the patients. early postoperative transtibial fistulae after AcL reconstruc-tion are rare complications that clinically present either as anterior tibial cysts or persistent wound drainage. Surgical

J. Díaz heredia (*) · M. A. ruiz Iban · r. ruiz Diaz · I. cebreiro Martinez del Val Department of Orthopaedic Surgery, hospital Universitario ramón y cajal, cta colmenar Km 9.100, 28034 Madrid, Spaine-mail: drdiazheredia@gmail.com

r. cuéllar Gutiérrez Department of Orthopaedic Surgery, hospital Universitario Donostia, San Sebastián, Spain

L. Turrion Merino Department of Dermatology, hospital Universitario ramón y cajal, Madrid, Spain

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Materials and methods

Between 2008 and 2010, a total of 223 AcL reconstruc-tions were performed in the authors’ institution. Of these, 188 cases were primary AcL reconstructions using autolo-gous hamstring grafts and an identical surgical technique. Three of them developed symptoms related to transtibial articular fistulae within the first two postoperative weeks.

AcL reconstruction technique and protocol

The surgical technique used in all 188 cases was identical: after clinical and arthroscopic confirmation of AcL insuf-ficiency, graft harvesting was performed through a longitu-dinal 2–3 cm long incision at the level of the pes anserinus insertion, 1.5 cm medial to the tibial tuberosity. The pes anserinus was exposed and was longitudinally disinserted completely from the tibial insertion 5 mm medially to the level of the anterior tibial tuberosity. The semitendinous and gracilis tendons were identified in the internal part of the pes, extracted with a tendon grafter and prepared to obtain a four-stranded graft at least 10 cm long. Bone tunnel size was matched to the nearest half millimetre with the graft; the tibial tunnel was performed using the same cutaneous and fascial incision used for graft extrac-tion with a standard tibial guide set at 55º and the femo-ral tunnel was performed with a transtibial technique and an over-the-top guide. Fixation was performed proximally with a cortical suspension implant (endobutton®, Smith and nephew, Andover. USA) and distally with a bioab-sorbable poly-l-lactide/hydroxyapatite composite inter-ference screw (Biosure®, Smith and nephew, Andover. USA). Screw width was 1 mm larger than the tibial tunnel and screw length was determined according to tibial tunnel length, using the larger screw possible (range 30–35 mm). After screw placement, the sartorial fascia was reinserted using three to five 2/0 Vicryl® (Johnson and Johnson, new Jersey, USA) interrupted stitches, the subcutaneous tissue was repaired using four to seven 2/0 Vicryl® (Johnson and Johnson, new Jersey, USA) interrupted stitches and a con-tinuous intradermal suture with 4/0 Vicryl® rapid (Johnson and Johnson, new Jersey, USA) was used for skin closure.

postoperatively all patients were discharged at the first postoperative day and evaluated in clinic at 1, 3 and 12 weeks. All patients were kept not-weight bearing for 3 weeks. Knee exercises were started under physical ther-apist supervision 1 week after surgery. range of motion exercises was limited to 0°–90º for the first 3 weeks.

clinical presentation

Three patients developed a transtibial fistula in the early postoperative period. There were two females and one male

(ages 22, 24 and 28, respectively). In the first two the tibial tunnel size was 8 mm, and in the third it was 9 mm. 35 mm long screws were used in all cases.

The transtibial fistula had two different clinical presenta-tions either as persistent wound drainage or pretibial cyst formation:

Cases 1 and 2: persistent wound drainage

In two cases (one male, 27 years old with body mass index 21 and one female, 25 years old with body mass index 20) the patients presented at clinic with a cutaneous fistula 6 and 8 days after surgery at the tibial wound. clear fluid appeared intermittently through a small not-healed portion of the otherwise clean and not inflamed tibial wound and the effusion increased with flexion and extension of the knee. The knee presented with mild swelling, no articular effusion and normal cutaneous temperature. Biochemical and haematological analysis of the fluid showed cytological and biochemical characteristic of inflammatory synovial fluid (less than 1,000 leucocytes per mm3 and glucose lev-els within 80 % of blood levels). Blood samples revealed normal leucocyte and neutrophil levels and c-reactive pro-tein levels below 5 mg/l [15]. Any radiological test was done in these patients.

Case 3: pretibial cyst

In the third case (female 23 years old with body mass index 18) the transtibial fistula appeared as a 2 cm subcutaneous mass that was noticed 14 days after the surgical procedure at the level of the tibial wound that had completely healed (Fig. 1). The mass was subcutaneous, not mobile and had minor variations in size, with increases in size associated with the physical therapy sessions. The knee presented minor swelling, minimal articular effusion and normal cutaneous temperature. Blood samples also revealed nor-mal leucocyte and neutrophil levels and c-reactive protein levels below 5 mg/l [15]. The patient was evaluated with magnetic resonance imaging, in which the cystic nature of the mass was confirmed and a communication through the screw hole between the intra-articular space and the preti-bial cyst was observed (Fig. 2).

Treatment

The wound fistulae in the two first cases were treated with compression dressings changed daily, but 1 week after, both patients presented persistent clear fluid drainage, and a reop-eration was indicated to avoid a secondary wound infection.

The patient with a cyst and a completely healed wound, a compression bandage was placed in the proximal tibial with the purpose of easing the resorption of the cyst. Four

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weeks after the cyst had not decreased in size and the deci-sion to reoperate the patient was taken.

reoperation was performed under spinal anaesthesia. The wound was opened through the previous scar. In all three cases a cavity surrounded with fibrinous tissue and filled with sero-hematic liquid was found immediately under the dermal plane, the cavity did not have a true wall. The fistula of the first two cases connected directly to this cavity. After opening and emptying the cavity, there was a clear 1–1.5 cm disruption at the repair of the sartorial fas-cia, the orifice of the tibial tunnel entrance was clearly seen and the direct communication with the screw hole between the articular space and the subcutaneous tissue was evident (Fig. 3). In all cases the distal part of the screw was slightly prominent over the bony tibial surface and was not totally inserted in the bone.

Samples of the fluid and the cyst wall tissue were sent for pathological and microbiological study. The tibial screws were not removed or exchanged in any of the pro-cedures. The fistulous tracks were resected and the false fibrinous wall of the cavities was debrided.

The tibial tunnel entrance was covered with 10 cc of Tis-sucol® in gel phase in the three cases and the closing was performed by careful dissection of the surrounding tissues; the sartorial fascia was identified and mobilized laterally over the defect and repaired to the periosteum and remain-ing lateral fascia with two to four 0 Vicryl® (Johnson and Johnson, new Jersey, USA) interrupted stitches. Subse-quently a meticulous closure of the subcutaneous tissue using four to seven 2/0 Vicryl® (Johnson and Johnson, new Jersey, USA) interrupted stitches was performed. Staples were used for skin closure.

Fig. 1 a The knee of case 3 7 weeks after Acl reconstruction: both arthroscopy portals and the tibial wound have healed uneventfully (localized decoloration is due to skin protection during sunbathing) but a 2 cm long subcutaneous mass, b at the level of the tibial wound can be observed

Fig. 2 MrI of the knee of case 3 (a sagittal cut in T1, b and c coro-nal cuts in T2). An anteromedial tibial cyst can be clearly appreciated (broad arrows) in direct continuity with the tibial tunnel. Fluid can

be appreciated in the joint, inside the screw hole (white arrow) and in the cyst. The interference screw is slightly prominent over the bone (small arrow)

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A compressive bandage over the proximal tibia was placed and maintained for 2 weeks. rest with not-weight wearing and dressing and bandage changes every 2 days were indi-cated for all three patients for 2 weeks and then the patients were reintroduced into the usual rehabilitation protocol.

At 2 years follow-up the three patients were evaluated by physical exam with Lachman and pivot-shift test [3], and functional evaluation with the Tegner [16] and Lysholm [17] scores.

Results

In all patients wound healing occurred uneventfully with-out recurrence of the cyst or wound drainage. The patho-logical and microbiological analysis of the surgical samples discarded the presence of infection. The pathology study indicated the presence of nonspecific fibrinous material. The reoperation implied a 3-week delay in the rehabilita-tion protocol.

At 2 years follow-up, all patients were asymptomatic with-out instability (pivot-shift-, and Lachman <5 mm), with good joint function and reinstated in their work and sporting activi-ties. Lysholm scale [17] scores were 90, 91 and 93 points, and the Tegner activity scale [16] levels were 6, 7 and 6.

Discussion

Of 188 consecutive primary AcL reconstructions per-formed in our institution with the same surgical technique,

three of them complicated with the appearance of sympto-matic transtibial articular fistula within the first postopera-tive days. In two cases the patients presented with articu-lar fluid drainage through a small not-healed portion of the tibial wound and in another case a 2 cm subcutaneous cyst appeared under a completely healed tibial wound. During reoperation a clear communication between the subcuta-neous tissue and the joint through the central interference screw hole was observed. Seal with Tissucol® and meticu-lous closing of the fascio-periostic structures over the dis-tal tibial tunnel hole was performed and all patients subse-quently healed uneventfully.

The presence of articular transtibial fistulae in the early postoperative period after AcL reconstruction has not been described previously. The cases presented here are clearly distinct from pretibial cysts that occasionally appear after AcL reconstruction, as these present much later, in the late postoperative period, between 6 months [13] and 6 years after surgery [14]. pretibial cysts have been described in cases with different grafts as autologous patellar tendon [5, 6, 8, 9, 18], hamstrings [7, 10, 11, 19–23], iliotibial band [14] and tendon allografts [13, 18] with a combination of various types of tibial graft fixation such as metal and resorbable interferential screws, staples or bone screws. There are two mechanisms by which these pretibial cysts develop: either there is joint fluid drainage from the joint through the tibial tunnel and into the cyst or a foreign body reaction occurs and a liquid collection develops. Drain-age through the tibial tunnel may have two causes: either a channel is developed due to inconsistency between the graft and tibial tunnel diameter (generally because of eccentric positioning of the graft [21], graft necrosis [8, 11, 13, 14] or excessive intratunnel graft mobility [21] ); or late postoperative tibial tunnel widening might generate an incongruity between tunnel and graft [24]. The other aeti-ology, foreign body reaction can appear due to reaction to the interferential bioresorbable screws (made of polyglyco-nate [5], poly dl-lactide [6, 18, 23, 25] or poly-l-lactide/β- phosphate-tricalcium composites [7, 22] ), or due to reac-tion to the suture material used for subcutaneous wound closure [9, 14, 20].

There are no references to the presence of fistula or sub-cutaneous cysts in the immediate postoperative period. In our experience all cases occurred in the first 2 weeks after surgery, even before cutaneous wound healing.

There are different etiologic mechanisms that might be concurrently involved in our patients: poor healing of the reattachment of the sartorial fascia near the midline, due to insufficient closure of the periosteum over the tibial drill tunnel, associated with a permeable central interference screw hole due to long screw use, and positive synovial liq-uid pressure due to joint swelling may generate a subcuta-neous space that is filled with joint fluid passing through

Fig. 3 Surgical image showing the slightly prominent interferential screw (arrow). A nitinol-wire was easily placed inside the screw con-firming the communication between the cyst and the intra-articular space

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the cannulated interferential screw. A too long interferential screw that is not inserted completely inside the bone tunnel might facilitate the fluid drainage to the subcutaneous tis-sue and hamper soft tissue healing and bone in growth in the distal tibial tunnel.

choosing a proper screw length that allows for counter-sinking of the screw inside the tibial surface without joint penetration and a more meticulous repair of the fascia and subcutaneous tissue might reduce the occurrence of these transtibial fistulae. In our institution, proper attention to these two factors has avoided further complications in the following years.

The patients with a persistent drainage of fluid through a not-healed wound were operated almost straightaway to avoid an infection. We tried a conservative treatment in the patient with a cyst for 4 weeks without success. When this rare complication appears, the surgeon should consider immediate reoperation. The treatment performed in our patients, curettage, seal with Tissucol® and fascia patch, was effective. Interference screw mobilization or bone grafting was not required in any case. In the published case series the pretibial cyst were surgically treated with cyst curettage and occasional bone grafting or tibial fixation material extraction [13, 14, 20, 21]. These techniques gave good results consistently.

Limitations

This is a case report and has the limitation of being based on a retrospective analysis of patients, this and the low inci-dence of the complication evaluated with a group consist-ing of a small number of subjects, makes it impossible to reach categorical conclusions.

Conclusions

early transtibial articular fistula formation after AcL reconstruction is a rare complication that is caused by joint fluid drainage through the tibial tunnel from the joint into the subcutaneous tissue, causing either a subcutaneous cyst or persistent drainage through the wound. The fluid drain-age happens through the central interference screw hole and can be attributed to deficient repair of the soft tissue around the tibial tunnel distal entrance and, sometimes, to protrusion of the distal end of the interferential tibial screw.

proper attention to the repair of the periosteum over the tibial drill tunnel entrance and with the measured of the length of the tibial tunnel should be done.

Although this complication requires a reoperation, it does not compromise the long-term outcome of the reconstruction.

Conflict of interest There are no conflicts of interest.

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