MPFL Case Discussion

MPFL Reconstruction Case Presentation

Introduction & Background:

                        The medial patellofemoral ligament (MPFL) is a band of retinacular tissue connecting the femoral medial epicondyle to the medial edge of the patella. The MPFL is approximately 55 mm long, and its width has been reported to range from 3 to 30 mm. The MPFL is overlaid by the distal part of vastus medialis obliquus to a variable extent, and fibers of MPFL merge into the deep aspect of the muscle. Despite the MPFL being very thin, it had a mean tensile strength of 208 N, and has been reported to be the primary passive restraint to patellar lateral displacement. Lateral patellar displacement tests in vitro showed that the patella subluxed most easily at 20 degrees knee flexion. The contribution of the MPFL to resisting patellar lateral subluxation was greatest in the extended knee. 

Anatomy:

Classification:

·        Wiberg type 1 or a

o   roughly symmetrical facets

o   concave facets

o   equally sized facets

o   although presumably the ideal shape of the patella, it is in fact rather uncommon, occurring in only 10% of the general population

·        Wiberg type 2 or b

o   slightly smaller size of the medial facet

o   concave aspect of the lateral facet

·        Wiberg type 3 or c

o   markedly smaller size of the medial facet

o   more vertical orientation of the medial facet

Patella was classified according to Baumgartl’s classification:

·       Type I patella: medial and lateral facets, both are concave with equal length

·       Type II patella: lateral facet is more prominent compared to the medial facet; medial facet is plane or concave.

·       Type III patella: a smaller and convex medial facet.

·       Type IV patella: no medial facet or central rim; as also called “Jokey hat”.

The Outerbridge MRI grading system was used for the degree of patellar chondromalacia

·       Grade 0: Normal.

·       Grade I: “Softening” or edema in the cartilage without contour irregularity.

·       Grade II: Surface irregularity, fissure or focal defect in less than 50%

·       Grade III: Fragmentation, fissure, or defect formation in 50% or more of the cartilage

·       Grade IV: Full thickness loss up to the bone and reactive changes in the subchondral bone

Classification of trochlear dysplasia (Dejour et al)

·        Type A: normal shape of the trochlea, but a shallow trochlear groove

·        Type B: markedly flattened or even convex trochlea

·        Type C: trochlear facet asymmetry, with too high lateral facet, and hypoplastic medial facet

·        Type D: type C features and a vertical link between facets ('cliff pattern') 

Patient Information:

Ø  Patient - ‘X’

Ø  Age - 22 years/ Male

Ø  Date of Admission: 10/04/2019

Ø  Date of Surgery: 11/04/2019

Chief  Complaint:

    The patient had pain over the left knee (knee cap). The patient had recurrent lateral patellar dislocation of the left knee.

History of Illness:

               The patient had a recurrent patellar dislocation and the patient feels instability of knee cap (patella) while flexing the left knee since fall. The patient gave a history of slip and fall at work in 2015 and December 2018.

            After the injuries, the patient took treatment in the nearby polyclinic. The patient had undergone conservative treatment but the conservative treatment didn’t help the patient. The patient contacted our hospital for further management(surgical treatment). The patient was examined by traumatologist and got admitted in the traumatology department. X-ray was taken and it showed no fracture of the patella.

v Previous Injury: The patient gave a history of the patellar dislocation

in 2015- 2 times.

in 2018- 4 times.

v Developmental History: No any developmental histories

v Drug History: No known drug allergies. The patient is not on treatment for CVS.

v Past Medical History: The patient gave a past medical history of Synovitis of the left knee with the chronic instability of the knee

No Diabetes mellitus; No Asthma; No thyroid disease.

v Past Surgical History: Joint aspiration of left knee & No any blood transfusion.

On Examination:

Patient is conscious, oriented.

Vital Signs:

·       BP – 120/80 mmHg

·       PR – 80/min

·       SPO2 – 99%

Local Examination:

·       Pain and chronic instability over the left patellar region are present.

·       Grasshopper sign +ve

·       Positive “J” sign

·       Patella glide test >2

·       Patellr grind test +ve

·       Insall-Salvati 2.1

·       Tibial Tuberosity – Tibial Groove (TT-TG) – 11.20mm

·       Positive apprehension test.

·       Active toe movements present.

·       Distal pulse present.

MRI Findings:

TT-TG – 11.20mm

Preparation:

Patient in Supine position: Place the patient on a radiolucent table. An adjustable Knee and Tibial Positioner kept beneath the lower extremity.

Procedure:

1.     Arthroscopic debridement of the left knee.

2.     AMTT (AnteroMedial Tibial Tuberosity) with distalization of the left knee.

3.     MPFL reconstruction of the left knee.

1. The patient under spinal anesthesia, place a tourniquet on the upper thigh. After sterile preparation and drapping, arthroscopy of the left knee joint was performed through standard anteromedial and anterolateral portals. During the procedure lateral positioning of the patella 2^nd stage, chondromalacia patella was revealed. Medial and lateral meniscus, ACL and PCL were not found damaged. Thorough wound washes given. Arthroscope removed. Aseptic bandage gave.

2. The patient under spinal anesthesia, after processing the operative field, access to the area of the proximal tibial tuberosity was performed with the longitudinal incision. The incision is made from the superior tip of the patella to the tuberosity of the supracondylar of the femur up to 5cm. 

  

After the subcutaneous lateral retinacular release of the patella, an osteotomy of the tibial tuberosity was performed. Then the anterior tibial tuberosity was moved medially with distalization, was fixed with 2 cortical screws.

3. From the same incision of the skin and underlying tissues in the projection of the “Pes Anserinus”, the ST tendon was found and separated, and the ST-G autotransplant was taken up to 20cm in length using a stripper.

Over the upper 3^rd  of the medial edge of the patella 2cm length of the channel has been madewith 4.5 mm drill, through which the graft of MPFL was transplanted.

  

After an additional incision of up to 2cm in length in the area of attachment of MPFL in the medial condyle of the femur,

7mm channel is formed, through which the autograft has been drawn and tightened, the autograft is then fixed with 9mm BIOSURE SCREW.

Thorough wound washes given. Wound closed in layers. Estimated blood loss 150ml. Compression bandage has been given. Immobilization did with a knee brace.

CLASSIFICATION:

   The above patient condition classified:

Ø  According to Wiberg - Type 2 or b

Ø  According to Baumgartl’s classification - Type II patella

Ø  According to Outerbridge MRI grading system was used for the degree of patellar chondromalacia – Grade II

Ø  According to Dejour et al – Type C

 CONCLUSION:

Ø  Surgical reconstruction, good anatomical reduction, and internal fixation help to recover the full range of movements.

Ø  Stability is restored.