Prospective Evaluation of Osseous Integration in ACL Reconstruction Comparing Tightrope vs Interference Screw Fixation
Condition: ACL - Anterior Cruciate Ligament Rupture
MeSH terms: Rupture
Study type: Interventional

Summary: 
      The purpose of our study was to compare osseous integration of the bone block in Achilles
      tendon allograft ACL reconstruction using a cortical button versus biocomposite interference
      screw fixation. The primary outcome was bone block incorporation within the femoral tunnel at
      six months. Our null hypothesis was that there is no difference in osseous incorporation or
      outcome with either type of femoral fixation in primary ACL reconstruction with Achilles
      tendon allograft. Our secondary outcomes were pain and clinical outcome scores between the
      two groups.
    

Detailed description: 
      After obtaining institutional review board approval the investigators conducted this
      prospective randomized controlled trial with goal of 1:1 allocation ratio between the two
      study groups. All subjects were recruited at the preoperative appointments. The senior
      investigator discussed ACL reconstruction with the patients. Appropriate preoperative
      counseling was performed regarding graft options. If inclusion criteria were met, patients
      received information about the study. Informed consent was obtained from those choosing to
      enroll in the study including consent for a CT scan at the six month postoperative time
      period. The patients were randomized for fixation technique on the day of surgery from a list
      using the medical record number. Patients underwent ACL reconstruction with Achilles tendon
      allograft with femoral-sided bone block fixation with either (1) a biocomposite interference
      screw (aperture fixation) or (2) cortical button (suspensory fixation).

      The inclusion criteria included patients between the ages of 18 and 50 able to provide
      informed consent with ACL tears meeting the indications for reconstruction and electing to
      undergo reconstruction with an Achilles tendon allograft. Excluded patients included those
      with a history of prior ACL reconstruction, pregnancy, inflammatory disease, a primary bone
      disorder, those taking bone resorption inhibitor medications, and those with injuries to the
      collateral ligaments or posterior cruciate ligament.

      All surgeries were performed by a single surgeon at a single institution using the same
      technique. Initial diagnosis of ACL deficiency was made on physical exam and magnetic
      resonance imaging. This was confirmed with arthroscopy at the beginning of the case. The
      Achilles-calcaneal bone allograft was thawed. The tendinous portion was tubularized and
      whip-stitched with a locking Fiberloop suture (Arthrex, North Naples, FL, USA). Sutures were
      passed through the bone block and the graft diameter was measured. The graft was then
      pre-tensioned. Femoral tunnels were made using the anteromedial portal at 120 degrees of knee
      flexion. The tibial tunnel was created using an outside-in technique over a pin centered at
      the ACL footprint. In the aperture fixation group, the bone graft end was pulled through into
      the femoral tunnel and secured with a biocomposite interference screw (BioComposite Screw,
      Arthrex, North Naples, FL; or MILAGRO screw, DePuy Mitek, Raynham, MA, USA). In the
      suspensory fixation group, a cortical button (TightRope, Arthrex, North Naples, FL, USA) was
      pulled through the femoral cortex and used to shuttle the Achilles bone plug into the femoral
      tunnel until it was just recessed within the medial intercondylar surface. In both groups,
      tibial fixation was identical with a bioabsorbable interference screw (BioComposite Screw,
      Arthrex, North Naples, FL, USA or Milagro screw) and a backup knotless anchor (4.5 mm Biomet
      Peek knotless anchor, Biomet, Warsaw, IN, USA). The graft was fixed at near full extension
      after having cycled the knee through range of motion with the graft tensioned.

      All patients underwent a specified ACL post-operative rehabilitation protocol depending on
      concomitant pathology. Cycling was permitted at the six-week mark. In-line jogging typically
      was allowed at four months with initiation of pivoting motions at seven to eight months. Full
      return to sports was allowed after nine months. Younger patients enrolled in a sports metrics
      program followed by a functional ACL exam prior to return to sports. A commuted tomography
      (CT) scan of the operative knee was obtained postoperatively at six months.

      Demographic data including age, gender, and body mass index were collected. The primary
      outcome measure was bony incorporation of the bone block within the femoral tunnel with CT
      scan. This was assessed with the femoral ossification score as determined by three board
      certified radiologists.

      The femoral ossification score was devised as a practical means of semi-quantitatively
      assessing the degree of bone incorporation around the femoral bone plug or screw fixation
      device present in each patient.

      Each CT scan score assessment was performed by one of three musculoskeletal
      fellowship-trained radiologists. Whenever an ossification score was deemed to be borderline
      between two categories, a consensus score was determined by two of the radiologists. The
      impression in the CT report included the femoral ossification score as well as a footnote
      with the entire scale to explain the score.

      Secondary outcome measures included pain score on a visual analogue scale (VAS) obtained
      preoperatively, at the first post-operative visit, and at return to sports. Physical
      examination findings included range of motion (ROM) and Lachman grading which were measured
      preoperatively and at return to sporting activities. Finally, the International Knee
      Documentation Committee (IKDC) subjective knee evaluation score, Tegner-Lysholm Knee score,
      and Cincinnati Knee Rating system scores were assessed both pre-operatively and
      post-operatively at return to sports.
    

Intervention name(s): Biocomposite intereference screw femoral tunnel fixation; Endobutton (Tightrope) femoral tunnel fixation
Intervention type(s): Device; Device
Intervention description(s): ACL reconstruction using biocomposite intereference screw for femoral tunnel fixation; ACL reconstruction using endobutton (Tightrope) for femoral tunnel fixation
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Participant)
Primary purpose: Treatment