MPFL Reconstruction 27422

patellar dislocation picture

patellar-dislocation-images

synonyms: MPFL reconstruction, Medial Patellofemoral Ligament Reconstruction, patellar dislocation repair

MPFL Reconstruction CPT

MPFL Reconstruction Anatomy

  • see MPFL anatomy.
  • Patellar stability is dependent on: bony constraint of the femoral trochlea; MPFL, medial retinaculum, and the vastus medialis. Any of these may be disrupted or dysplastic in patients with patellar instability. (Conlon T, JBJS 1993;75Am:682).
  • >94% of patellar dislocations are related to MPFLrupture, generally from its femoral origin.

MPFL Reconstruction Indications

  • Chronic / Recurrent patellar dislocation
  • Acute dislocation with osteochondral injury
  • Acute dislocation in high level athlete
  • Patellar instability with trochlear dysplasia

MPFL Reconstruction Contraindications

  • Infection
  • Patellar alta (consider concomitant distal transfer to the tibial tubercle)

MPFL Reconstruction Alternatives

  • Extensor mechanism realignment
  • Trochleoplasty (Verdonk R, Knee Surg Sports Traumtol Arthrosc. 2005;13:529).
  • Anterior femoral osteotomy (Weiker G, Am J Knee Surg 1997;10:221).

MPFL Reconstruction Planning / Special Considerations

  • Arthrex MPFL reconstruction technique.  MPFL Graft:  A gracilis or semitendinosis (autograft vs allograft.  Graft should be approximately 4 mm in diameter and minimum graft length is 18 cm.  Graft is whipstitched 10 mm at each end with a 2-0 FiberWire suture.   Taper ends to facilitate insertion into patella.
  • Consider concomitant distal transfer of the tibial tubercle for patients with patellar alta.
  • Through-tunnel tendon graft provides strongest MPFL reconstruction (Mountney J, JBJS 2005;87Br:36).

MPFL Reconstruction Technique

  • Pre-operative antibiotics, +/- regional block
  • General endotracheal anesthesia
  • Supine position. All bony prominences well padded.
  • Examination under anesthesia: ROM 0-130; varus laxity ext/30; valgus laxity ext/30; anterior drawer ER/IR, posterior drawer; lachman; pivot shift; ->10 degree increase in ER at 30° flexion, but not at 90 degrees. Patellar tilt, patellar subluxation.
  • Tourniquet high on thigh.
  • Prep and drape in standard sterile fashion.
  • Perform routine knee arthroscopy. Repair any large osteochondral injuries to the patella if possible. Fixation may be provided with chondral darts or sutures through bone tunnels. Remove any small fragments, debride and microfracture.
  • 3-4cm longitudinal incision midway between the patella and the medial epicondyle.
  • Incise sartorius in line with its fibers.
  • Identify inferior border of the Vastus medialis. The MPFL is just deep to the Vastus medialis.
  • In acute situations locate the MPFL injury and repair +/- imbrication. It is most commonly avulsed from its medial epicondyle insertion which can be repaired with suture anchors.
  • MPFL Reconstruction: Isometric location determined with a tensiometer. Graft tensioned at 60-90°. Graft options: quadriceps autograft, adductor magnus autograft, patellar tendon allograft, semitendinosis all/auto graft, tibialis anterior allograft etc. Fixation options include interference screws, Arthrex biotenodesis screws, Arthrex retrobutton in patella, suture anchors, etc.
  • Arthrex MPFL reconstruction: 
  • Graft: gracilis autograft, gracillis or semitendinosis allograft;  Minimum graft length = 18 cm.   Whipstitch10 mm at both ends and taper the ends.
  • 2 cm skin incision from the superomedial corner or patella, extending distally. 
  • Dissect down and expose the medial edge of the patella.
  • Drill 2.4mm guide pin 3 mm distal to the proximomedial corner of the patella, transversely
  • Second 2.4 mm Guide Pin 15-20 mm distal and parallel to the first
  • Over-drill the two guide pins with a 4.5 mm cannulated reamer to a depth of 25 mm.
  • Insert graft into patella using two  4.75 mm BioComposite anchors.
  • Identify femoral insertion: 1 mm anterior to the posterior cortex extension line;  2.5 mm distal to the posterior articular border of the medial femoral condyle; proximal to the level of the posterior point of Blumensaat’s line. 
  • Drill 2.4 mm guide pin   across the femur and out the lateral epicondyle. 
  • Over-ream the femur  7 mm Low Profile Reamer
  • Dissect between vastus medialis and the capsule towards the femoral insertion area
  • Loop the graft through a passing suture 
  • Pass the graft to femoral insertion incision.
  • Place a 1.1 mm Nitinol guidewire into the drill hole next to the femoral guide wire 
  • Pass the passing suture through the femoral tunnel using guidewire. 
  • Pretension the graft and insert it into the socket with equal tension on both graft bundles
  • Tension the graft  at 30 ̊ of flexion and fix with 6 mm x 23 mm interference screw 
  • Evaluate the tracking and laxity of the patella throughout the knee ROM.
  • Irrigate.
  • Close in layers.

MPFL Reconstruction Complications

  • Continued instability, dislocation
  • Arthrofibrosis
  • Infection
  • Anterior knee pain / kneeling pain
  • Neurovascular injury (saphenous vein, saphenous nerve)
  • Painful hardware
  • Patellofemoral arthritis
  • Patellar fracture

MPFL Reconstruction Follow-up care

  • Post-Op: hinged-knee brace, ROM 0-60°, WBAT with crutches in brace.  Begin straight leg raise home exercises.
  • 7-10 Days: wound check. Start ROM and quadriceps exercises with physical therapy.
  • 6 Weeks: discontinue knee brace if quadriceps function and knee motion are normal.
  • 3 Months: sport specific rehab.
  • 6 Months: return to sport / full activities.

MPFL Reconstruction Outcomes

  • 91.1% good/excellent results for MPFL reconstruction (Steiner TM, AJSM 2006;34:1254).
  • 93% good/excellent result the hamstring autograft (Drez D, Arthroscopy 2001;17:298).

MPFL Reconstruction Review References