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Role of osteotomy in patellar mal-tracking 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 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’’ Eckhoff DG,(1997). Clin Orthop Relat Res The source of such abnormal patellar kinematics may be Peri-patellar tissue tightness or laxity Osteo-chondral dysplasia (trochlear) Bony abnormalities of the patella 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 Well-known risk factors for symptomatic PF malalignment include Genu valgum Patella alta Trochlea dysplasia Increased TT- TG distance Femur or tibia mal-rotation 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 Deviations in normal limb alignment Knee joint flexion-extension axis advancing sideways While the body moves forward These deviations include Excess femoral anteversion or retroversion Excess internal or external tibial torsion Genu valgum or varum Foot hyper-pronation Achilles contracture 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 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 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 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 A similar increase of inward pointing of the knee joint Excess external tibial torsion when the foot is pointed forward Compression on the lateral patellar facet is increased Compression on the medial patellar facet is decreased The clinical presentation may be Pain Instability Arthrosis Combination of these problems If this force is great If the trochlear support is reduced Medial ligaments may fail, resulting in lateral patellar instabilIty 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 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 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 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 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 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 Fujikawa, K;Biomechanics of the patello-femoral joint. Eng Med ,1983 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 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 • Clinical symptoms with Angle > 2SD on CT Scan • Rotational osteotomy Distal realignment procedures modify the Medial-lateral Anterior-posterior Proximal-distal positions of the patella by transfer of the tibial tubercle The primary contraindication Absence of a distinct anatomic defect Because the goal of surgery is to restore normal anatomy of the extensor mechanism 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 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 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 Cartilage lesions typically Infero-lateral portion of the lateral patella facet Lateral region of the trochlea Indications for surgery Recurrent dislocations Anterior knee pain that has not responded to conservative treatment 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 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 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 Indications (Fulkerson) Patello-femoral pain Either lateral or distal patellar arthrosis Lateral subluxation/dislocations of the patella 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 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 May be better treated with an isolated lateral release 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
