Patello femoral instability 22

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Patello femoral instability 22

  1. 1. PTELLOFEMORAL INSTABILITY Dr.G.Ramesh M.S(Ortho) Asst.Professor Dept. of Orthopaedics Gandhi Medical College Secunderabad
  2. 2. PATELLO FEMORAL INSTABILITYINTRODUCTION: patello femoral instability is a common but challenging treatment problem for an orthopaedic surgeon The patellofemoral joint has a low degree of congruency by nature, hence it is susceptible to dislocation Dislocation is a result of anatomical abnormalities and/or insufficient soft tissue restraints Non-surgical approaches have been advocated to treat acute patellar dislocation, while many operative procedures, including proximal soft tissue or distal bony realignment procedures are designed to treat chronic / recurrent patellar dislocations Addressing the specifics of anatomy, biomechanics, history, physical examination , and radiographic interpretation can shed important light on the treatment options of acute and recurrent patellar dislocations/and subluxations
  3. 3. PATELLO FEMORAL INSTABILITYAnatomyPassive stabilizers1. trochlear groove : primary bony stabilizers: depth, height patellar engagement2 medial patello femoral ligament (MPFL): primary static soft tissue stabilizerDynamic stabilizer quadriceps (VMO)
  4. 4. PATELLO FEMORAL INSTABILITY Biomechanics stability and normal tracking of the patella with knee flexion requires a complex co ordination of static and dynamic stabilizers. From o° to 30° ofthe knee flexion, medial patello femoral ligament and other soft tissue are primary restraints to lateral patellofemoral dislocation. With the greater knee flexion , the bony confines of the lateral femoral condoyle and trochlear groove captures the patella and patellar stability
  5. 5. PATHOLOGIC ANATOMY OF PATELLAR DISLOCATIONH. dejour classificationPrimary instability factors1. Trochlear dysplasia2. Patella alta3. Patella tilt4. ↑ TT-TG distance(‘q’ angle quantification by CT scan)Secondary instability factors1. Excessive external femoral rotation / Excessive femoral ante version2. Excessive external tibial rotation3. Genu valgum4. Genu recurvatum ( these underlying pathologies predispose to an acute over load of soft tissue stabilizers and rupture of MPFL with patellar dislocation following minimal trauma)
  6. 6. PATELLO FEMORAL INSTABILITYWho tends to recur• Young• Female• Family history• Bilateral• Atraumatic disorders• Anatomic abnormalities patella alta trohlear hypoplasia ↑TT-TG distance ↑ ‘q’ angle quadriceps dysfunction hyper mobility
  7. 7. PATELLO FEMORAL INSTABILITYEvaluationWe evaluate the following features1. Integrity of medial patello femoral ligament2. Height of patella on physical and radiographic examination3. Length of patellar tendon4. Position of patella in relationship to trochlea
  8. 8. PATELLO FEMORAL INSTABILITYphysical examination gait standing alignment ‘Q’ angle J sign laxity rotational malalignment
  9. 9. PATELLO FEMORAL INSTABILITYphysical examination gait standing alignment ‘Q’ angle J sign laxity rotational malalignment for males : mean ‘Q’ angle is 10͔° for females : mean ’Q’ angle is 15°±5° ↑’q’ angle leads to relative lateral shift of patella ↑’Q’ angle results from ↑femoral external rotation ↑external rotation genu valgum tibia vara
  10. 10. PATELLO FEMORAL INSTABILITYphysical examination gait standing alignment ‘Q’ angle J sign laxity rotational malalignment observe the movement of the patella during active knee extension, lateral subluxation of the patella as the knee approaches full extension is indicative of j sign positive positive j sign indicates ↑ lateral force or ↑ ‘q’angle
  11. 11. PATELLO FEMORAL INSTABILITYphysical examination gait standing alignment ‘Q’ angle J sign laxity rotational malalignment patellar laxity patellar translation is assessed by passively moving patella medially and laterally with knee at 0° and 30° of flexion, the amount of translation is quantified in quadrants. Normal glide is one but more than two quadrants indicates laxity
  12. 12. PATELLO FEMORAL INSTABILITYphysical examination gait standing alignment ‘Q’ angle J sign laxity rotational malalignment patellar tilt it is done with knee in full extension normally patella can be tilted so that the lateral edge is well anterior to the medial edge inability to do this indicates lateral retinacular tightness
  13. 13. PATELLO FEMORAL INSTABILITYphysical examination gait external tibial torsion standing alignment ‘Q’ angle J sign laxity rotational malalignment Measured by he relation ship of the transmalleolar axis to the Coronal axis of the proximal tibia, is typically neutral tibial torsion also may be assessed through measurement of the thigh-foot angle, average values are 5°internal leads to ↑’Q’ angle and ↑ TT-TG distance
  14. 14. PATELLO FEMORAL INSTABILITYphysical examination gait excessive femoral ante version standing alignment ‘Q’ angle J sign laxity rotational malalignmen measured by hip rotations with the patient in prone position with hips extended and knees at 90°of flexionNormal range of hip rotations are about 45°. With ↑ femoral antevertion range of I.R. increases and range of E.R. reduced conditions leads to ↑’q’angle and ↑TT-TG distance
  15. 15. PATELLO FEMORAL INSTABILITYRadiographic evaluation1. long standing weight bearing hip-to-ankle, A.P view helps in assessing the angular deformity of knee i.e. genu varum and genu valgum
  16. 16. .. PATELLO FEMORAL INSTABILITY Radiographic evaluation Lateral view with 30° of knee flexion Insall-salvati ratio: normal value: 1.0 to 1.2 ↑value indicates: patella alta When patella alta is present ,the patella becomes engaged with greater degrees of knee flexion , where the patella is not captured and it is at increased risk for instability
  17. 17. PATELLO FEMORAL INSTABILITYRadiographic evaluationLateral view with 30° of knee flexiontrochlear dysplasia: crossing sign double contour
  18. 18. PATELLO FEMORAL INSTABILITYRadiographic evaluationMerchants view: tangential axial view of patello femoral joint obtained with knee in 45° of flexionSulcus angle normal angle : 140° > 140° : trochlear dysplasiaCongruence Angle normal : -8°to+14° >14° indicates lateral subluxationLateral Patello Femoral Angle normal: angle opens laterally abnormal : angle opens medially or lines become parallel
  19. 19. PATELLO FEMORAL INSTABILITYCT scan evaluation• Helps in assessing the bony anatomy and architecture of patello femoral joint at different angles of knee flexion• The protocol includes mid-axial images obtained from 0°to60° of flexion in 10° of increments• Is quantification of ‘q’ angleTT-TG distance : normal measures are 2to 9 mm borderline measures are 10to 19 mm pathological > 20°Sulcus angleCongruence angleTrochlear depth
  20. 20. PATELLO FEMORAL INSTABILITYCT scan evaluationThe protocol includes mid-axial images obtained from 0°to60° of flexion in 10° of increments
  21. 21. MANAGEMENT OF PATELLO FEMORAL INSTABILITYTypes of patellar dislocations Acute patellar dislocations Chronic / recurrent patellar dislocationsAcute patellar dislocations Results from high energy transfer, where anatomy of joint is normal Results from internal rotation of femur on a fixed externally rotated tibia Major sequelae of acute patellar dislocation is tear of medial patello femoral ligament (MPFL) In general most acute dislocations are treated non-operatively unless associated with an osteochondral injury When surgery is needed MPFL is repaired / reconstructed
  22. 22. MANAGEMENT OF RECURRENT PATELLAR INSTABILITY Defined as the condition where patellar dislocation had occurred at least twice, or where patellar instability following initial dislocation had persisted for more than three months A large number of procedures have been described to treat recurrent patellar dislocations No single surgery is universally successful in correcting the chronic patellar instability We need to customize surgery based on the knee problem Our approach is to identify the underlying problem that cause the patello femoral instability and systemically correct them
  23. 23. MANAGEMENT OF RECURRENT PATELLAR INSTABILITYThe surgical procedures are classified into Proximal Realignment Of Extensor Mechanism 1.Lateral retinacular release 2. Medial plication/ reefing 3. VMO advancement 4.MPFL reconstruction Distal Realignment Of Extensor Mechanism Medial or antero medial displacement of tibial tuberosity
  24. 24. MEDIAL PATELLO FEMORAL LIGAMENT RECONSTRUCTION The procedures like medial plication, vmo advancement, and lateral retinacular release are non anatomic procedures They don’t address the principle of pathology in recurrent patellar dislocation Medial patello femoral ligament (MPFL) is the primary soft tissue passive restraint to pathologic lateral patellar dislocation, and MPFL is torn when patella dislocates, hence reconstruction of MPFL is done in an attempt to restore its function as a checkrein
  25. 25. MEDIAL PATELLO FEMORAL LIGAMENT RECONSTRUCTIONAnatomy of medial patellofemoral ligament MPFL arises from medial surface upper two thirds of patella above equator and inserts into a groove between adductor tubercle and medial epicondyle
  26. 26. MEDIAL PATELLO FEMORAL LIGAMENT RECONSTRUCTIONProcedureindicated in : skeletally mature patient excessive lateral laxity normal trochlea ‘Q’ angle is normal TT-TG distance is < 20mm low grade trochlear dysplasiaContraindications : skeletally immature patients where MPFL is normal
  27. 27. MEDIAL PATELLOFEMORAL LIGAMENT RECONSTRUCTIONProcedure Examination under anaesthesia Hamstring graft preparation Exposer of MPFL
  28. 28. MEDIAL PATELLO FEMORAL LIGAMENT RECONSTRUCTIONProcedure Patellar tunnel preparation Femoral tunnel preparation Femoral tunnel graft passage and fixation Graft passage through patellar tunnel and fixation Wound closure
  29. 29. DISTAL REALIGNMENT SURGERYFullkerson antero-medial tibial tuberosity transfer aims to diminish the q angle or TT-TG distance with medialisation of tibial tuberosity and unloads patello femoral articulation with anteriorisation of the tubercleIndications1. ↑ Q angle or ↑ TT-TG distance > 20mm2. Patellar alta3. Normal patellar glide4. Medial facet arthritisContraindications1. Skeletally immature patients2. incompetent MPFL3. Diffuse patellar arthritis
  30. 30. Fullkerson antero-medial tibial tuberosity transferProcedure Routine lateral retinacular release is done An oblique osteotomy is made from ateromedially close to anterior tibial crest directed in postero lateral direction ,existing at lateral cortex posteriorly Mitek tracker drill guide with cutting slot is used to define precise osteotomy plane Bone pedicle is displaced in an antero medial direction usually about 12to 17mm of anterization depending on obliquity of osteotomy
  31. 31. TROCHLEAR DYSPLASIA The normal trochlea is located in the anterior aspect of the distal femur. It is composed of two facets divided by the trochlear sulcus The lateral facet is the biggest, it extends more proximally than medial facet and is more protuberant in A.P. Aspect Dysplastic trochleas are shallow, flat or convex These trochleas are not effective in constraining mediolateral patellar displacement Is defined by a sulcus angle > 140°
  32. 32. TROCHLEAR DYSPLASIARadiological featuresX- ray lateral projection of normal trochlea will typically show the contour of the facets, and posterior to them, the line representing the bottom of the sulcus is visualized and is continues with the intercondylarnotch line
  33. 33. TROCHLEAR DYSPLASIARadiological featuresCrossing sign The radiographic line of trochlear sulcus crosses he projection of the femoral condyles The crossing point represents the exact location of the deepest point of trochlear sulcus which is about 0.8mm posterior to a line projected from anterior femoral cortex, in dysplastic trochlea it’s an point is 3.2mm forward to same
  34. 34. TROCHLEAR DYSPLASIARadiological featuresTrochlear spur the supratrochlear spur corresponds to an attempt to contain the lateral displacement of the patella
  35. 35. TROCHLEAR DYSPLASIARadiological featuresDouble-contour signrepresents the hypo plastic medial facet, seen posterior to the lateral facet in lateral view
  36. 36. TROCHLEAR DYSPLASIAClassification of trochlear dysplasiaType A: crossing sign + the trochlea is shallower than normal, but still symmetrical and concaveType B: crossing sign + supratrochlear spur +the trochlea is flat or convex in axial view
  37. 37. TROCHLEAR DYSPLASIAClassification of trochlear dysplasiaType C: crossing sign + double-contour sign + supratrochlear spur – representing hypoplasia of medial facet and lateral facet convexType D: crossing sign + double-contour sign+ supratrochlear spur +clear asymmetry of the height of facets, and referred to as a cliff pattern
  38. 38. MANAGEMENT OF TROCHLEAR DYSPLASIASurgical indications High grade trochlear dysplasia with patellar instability in the absence of patellofemoral osteoarthritis Type of dysplasia should be identified when deciding the procedure Associated abnormalities including TT-TG distance, patellar alta, patellar tilt should be identified and rectified MPFL reconstruction is always doneContra indications Skeletally immature patients Associated osteoarthritis
  39. 39. MANAGEMENT OF TROCHLEAR DYSPLASIAType of dysplasia and surgical procedureType A dysplasia : medial patellofemoral ligament reconstructionType B and D dysplasia : sulcus deepening trochleoplasty with MPFL reconstructionType C dysplasia : lateral facet elevation trochleoplasty with MPFL reconstruction
  40. 40. MANAGEMENT OF TROCHLEAR DYSPLASIAProcedure: sulcus deepening trochleoplasty by Henrey Dejour Indicated in type B and D trochlear dysplasia with patellar dislocation It is designed to establish a new trochlear groove of correct length and tilt , addressing the root cause of patellar dislocation due to trochlear dysplasia The femoral trochlea is deepened by removing the subchondral trochlear bone followed by incision, impaction, and fixation of cartilage flare along the trochlear groove
  41. 41. MANAGEMENT OF TROCHLEAR DYSPLASIAProcedure pre-operative post-operative
  42. 42. MANAGEMENT OF PATELLOFEMORAL INSTABILITYA management algorithm is proposed for clinical use
  43. 43. CONCLUSION Patellofemoral instability can be difficult to treat Acute patello femoral dislocations should be treated with immobilization and rehabilitation. Arthroscopy should be indicated for symptomatic osteochondral injury In recurrent patellofemoral dislocations, it is important to understand each patients reason for repeated instability. The reason can be determined through a detailed history, focused physical examination, and radiographic studies including CT scan and MRI Once determined proximal realignment procedures, distal realignment procedures, trochleoplasty or a combination of above procedures can be tailored to the individual patient and be utilized to correct patellofemoral biomechanics
  44. 44. Thank you

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