Role of osteotomy in patellar maltracking Hadi H

Role of osteotomy in patellar mal-tracking Hadi H. MD Knee surgery fellowship Arak & Iran UMS

Introduction Patellar mal-alignment may be defined as a �Translational or rotational deviation of the patella relative to any axis It is caused by an abnormal relationship between �Patella �Soft tissues surrounding the patella �Femoral and tibial osseous structures

Introduction Eckhoff stated that �‘‘the patella is a passive component of the extensor mechanism, where the static and dynamic relationships of the underlying tibia and femur determine the patellar tracking pattern’’ ü Eckhoff DG, (1997). Clin Orthop Relat Res

Introduction The source of such abnormal patellar kinematics may be �Peri-patellar tissue tightness or laxity �Osteo-chondral dysplasia (trochlear) �Bony abnormalities of the patella

Introduction The source of such abnormal patellar kinematics may be �Rotational mal-alignment of the femur and tibia �Patella alta and patella baja �Inflexibility or weakness of the quadriceps hamstrings, and iliotibial band (ITB), Achilles tendon

Introduction Well-known risk factors for symptomatic PF malalignment include �Genu valgum �Patella alta �Trochlea dysplasia �Increased TT- TG distance �Femur or tibia mal-rotation

Introduction The key to the indications for surgical treatment is �Diagnosis of the specific anatomic defects that cause the patient's symptoms �This underscores the importance of the history and physical examination �Abnormal findings are often quite subtle, leading to a major problem

Mal-alignment � Deviations in normal limb alignment � Knee joint flexion-extension axis advancing sideways � While the body moves forward

Mal-alignment These deviations include �Excess femoral anteversion or retroversion �Excess internal or external tibial torsion �Genu valgum or varum �Foot hyper-pronation �Achilles contracture

Rotational Mal-alignment Torsional deformities of the femur and/or tibia �Often go unrecognized in both adolescents and adults �Who present with anterior knee pain, and patellar mal-tracking and/or instability

Rotational Mal-alignment foot progression angle (FPA) �Averages 10° to 15° �Remains similar despite differences in the torsion of the tibia or femur �Hip rotation must vary if the torsion of the long bones changes and the FPA stays constant

Rotational Mal-alignment Constant foot progression angle (FPA) is likely because �Proper ankle dorsiflexion cannot occur during gait if the ankle joint axis is not aligned with the direction of forward movement �Most stable position of the foot on the ground

Rotational Mal-alignment If the knee joint twists inward because the femur twists inward � Lateral pull on the quadriceps � Lateral displacement pull on the patella � Strain on the medial MPFL Are increased

rotational Mal-alignment � A similar increase of inward pointing of the knee joint � Excess external tibial torsion when the foot is pointed forward

Rotational Mal-alignment �Compression on the lateral patellar facet is increased �Compression on the medial patellar facet is decreased

Rotational mal-alignment The clinical presentation may be �Pain �Instability �Arthrosis �Combination of these problems

Rotational mal-alignment � If this force is great � If the trochlear support is reduced � Medial ligaments may fail, resulting in lateral patellar instabil. Ity

Rotational mal-alignment � If the trochlear support is normal � The ligament may not fail but the articular load may increase, causing arthrosis � Pain in the medial retinaculum is a common symptom caused by this increased stress

Rotational mal-alignment � The dynamic picture is much worse � Ante-version puts the greater trochanter pointing posteriorly � So there is no hip abduction power and the pelvis collapses

Rotational mal-alignment � In an attempt to increase hip power and put the foot forward � The knee joint must point inward � Even more when there is an increase in hyper-pronation

Rotational mal-alignment Yoshioka and associates (1989, J. Orth. Rech. ) found in male & female �Identical femoral ante-version equal genu valgus �But an increase in external tibial torsion foot external rotation in females over males

Rotational mal-alignment This increase in external foot rotation may account for �The apparent increased genu valgus in females �The increased incidence in PF symptoms in females �Even the increased incidence of ACL tears in females

Rotational mal-alignment Biomechanical study that measured PF contact pressures concluded that �If an angular deformity and a torsional deformity coexist, the rotatory component causes the greater PF changes ü Fujikawa, K; Biomechanics of the patello-femoral joint. Eng Med , 1983

Mar-rotation Treatment �The goal of operative treatment is to normalize the biomechanics through restitution of normal anatomy �The morbidity of surgery may dictate otherwise �When multiple anatomic abnormalities exist, it is not known which may be more important

Indication Surgery is indicated �Torsion of the femur or tibia exceeding 30° from normal Surgery is beneficial �Torsion exceeding 20° from normal �Abnormality less than 20°, the accuracy of surgery or the morbidity may not justify the smaller biomechanical changes

Indication • Clinical symptoms with Angle > 2 SD on CT Scan • Rotational osteotomy

Tibial tubercle transfer (TTT) Distal realignment procedures modify the �Medial-lateral �Anterior-posterior �Proximal-distal positions of the patella by transfer of the tibial tubercle

Distal realignment (TTT) The primary contraindication �Absence of a distinct anatomic defect �Because the goal of surgery is to restore normal anatomy of the extensor mechanism

Distal realignment (TTT) A specific contraindication to extensor mechanism surgery is the presence of �Excessive hip anteversion or �Abnormal external tibial torsion �In these patients, a femoral or tibial derotation osteotomy may be indicated

Distal realignment Patella alta �Congenital abnormality �An increased vertical position of the patella �Due to an elongated patellar tendon �Patella not engaging within the trochlea until a mid -flexion range of motion �Patella instability or pain

Patella alta �Decrease in PF joint contact area at all knee flexion angles �Risk for early PF arthritis �In most patients, other abnormalities of the extensor mechanism are usually present

Patella alta Cartilage lesions typically �Infero-lateral portion of the lateral patella facet �Lateral region of the trochlea

Distal realignment (Distalization) Indications for surgery �Recurrent dislocations �Anterior knee pain that has not responded to conservative treatment

Distal realignment (Distalization) �Patient is advised that symptoms of anterior knee pain related to the arthritis will continue �It is thus preferable to correct a symptomatic patellar alta condition early prior to the development of cartilage deterioration

Distal realignment (Distalization) The goal � Restore a normal patellar height index � Patello-trochlear contact (~30% of the inferior patellar articular cartilage) has engaged the trochlear at full extension

Distal realignment (Distalization) When a distal transfer of the patellar tendon �Tenodesis of the tendon at the tibial insertion site would restore normal tendon length �Decrease side-to-side patellar mobility, given the high percentage of associated trochlear dysplasia

Distal realignment (AMZ) Indications (Fulkerson) �Patello-femoral pain �Either lateral or distal patellar arthrosis �Lateral subluxation/dislocations of the patella

Distal realignment (AMZ) The ideal candidate is someone with �Lateral patellar tilt (and/or subluxation) associated �With grade III or IV articular degeneration �Localized to the lateral and/or distal medial patellar facets

Distal realignment (AMZ) Contraindications �No mal-alignment �Occult medial patella subluxation �Diffuse patellar articular cartilage disease (especially at the proximal pole) �Mild articular changes (grade I or II) with tilt, and no subluxation ü May be better treated with an isolated lateral release

Conclusion In patella mal-tracking �Abnormal findings are often quite subtle, but combinations are surprisingly common �Torsional deformities are often unrecognized �For local cartilage lesions distal realignment may be appropriate �Exact pre-op planning is necessary for satisfactory outcome

Thanks for your attention