Patellar Instability
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This document discusses patellar instability, including relevant anatomy, predisposing factors, clinical features, radiological evaluation, and management. It begins with an introduction classifying patellar instability as acute, recurrent, or habitual. Relevant anatomy includes the patella, trochlea, and static and dynamic stabilizers of the patellofemoral joint. Risk factors include ligamentous laxity, alignment issues, and anatomical factors like patella alta or trochlear dysplasia. Clinical exams and radiological tests are used to evaluate patients. Management involves conservative treatments like bracing and physical therapy or surgical options like lateral release, MPFL reconstruction, and realignment procedures depending on the individual case.
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Patellar Instability
- 1. PATELLAR INSTABILITY PRESENTER : DR. BIJAY MEHTA MODERATOR : DR. ANIL K GUPTA
- 2. CONTENTS Introduction Relevant anatomy Predisposing factors Clinical features Radiological evaluation Management Summary
- 3. Introduction • Patellar dislocation accounts for 3% of all knee injuries. • Female adolescents • Recurrence rates • After 1st dislocation-17%, with dysplasia -60% • After 2nd dislocation -50% •Mainly lateral, medial typically iatrogenic
- 4. • Acute • Single episode after a significant trauma • Almost always lateral • Recurrent • Repeated occasional dislocations • Occurs at intervals of week or months • Habitual • Patella dislocates every time knee is flexed • Patella cannot be held in position throughout full ROM Classification
- 5. Patella: Anatomy •Largest sesamoid bone within the quadriceps •Articular surface- divided by a vertical ridge
- 7. Patellofemoral Joint Stabilizers Static • Shape of patella • Shape of femoral sulcus • Patellar tendon of • Capsule • Retinaculum • Ligaments • Medial Patellofemoral ligament(MPFL)
- 8. Patellofemoral Joint Stabilizers Dynamic • Quadriceps muscles • Vastus medialis obliqus
- 10. Q angle Male 8-10 Female 15 +/- 5
- 11. Risk Factors General Factors •Ligamentous laxity •Previous traumatic event •Miserable malalignment syndrome Anatomic Factors •Osseous • Patella alta • Trochlear dysplasia • Patellar Dysplasia • Excessive lateral patellar tilt •Muscles • Dysplastic VMO • Overpull of lateral structures- ITB, Vastus lateralis
- 12. Shape of Patella Wiberg Classification for Patellar Shape
- 13. Factors increasing Q angle
- 14. Symptoms •Pain around knee aggravated on walking uphill/downhill or stairs •Feeling of insecurity and knee cap giving away •Patellar crepitation •Knee swelling
- 15. Examination •Patellar height in seated position : high/low riding patella •Dynamic Patellar tracking • Positive J sign with knee extension- indicates patellar maltracking •Active patellar tracking
- 16. •Measure Q-angle •Patellar grind test • Pressure over patella • Displace it medially, laterally, superiorly and inferiorly in the trochlear groove • Positive test: Anterior knee pain with a pathologic condition of patellofemoral joint Examination
- 17. Examination •Fairbanks apprehension test •Patellar tilt test • Knee in 20 degree flexion • Inability to raise the patella with thumb and finger to the horizontal plane or slightly past indicates excessive lateral retinacular tightness
- 18. Examination •Patellar Glide Test • Patella is divided into 4 longitudinal quadrants • Patella is displaced medially • Medial translation of one quadrant or less is suggestive of excessive retinaculum tight ness
- 20. Rotational Profile of Staheli •Craig test •Thigh –foot angle •Foot progression angle Examination
- 21. Examination •Previous cited factors increasing the Q angle • Genu valgus • Excessive femoral anteversion • External tibial torsion • Lateral tibial tuberosity
- 22. Radiographic Evaluation Xray knee; AP view • Bipartite patella • Osteochondral defects
- 23. Radiographic Evaluation Xray knee: Lateral view • Blumensaat line
- 24. Radiographic Evaluation Insall and Salvati index(0.8-1.2) Caton Deschamps ratio(0.6-1.3) Blackburne Peel ratio(0.54-1.06)
- 25. Axial images
- 26. Axial images
- 27. Axial images Measurement of Sulcus angle and congruence angle
- 28. Axial images Patellar tilt(CT) Normal <20 Angle >20 - dysplasia
- 29. TT-TG distance >20 mm suggests mal-alignment
- 30. CT Scan : Lyon’s Protocol
- 31. Trochlear Depth ≤4mm- pathological ≤3mm- pathological
- 32. Trochlear dysplasia- Dejour’s Classification Type A
- 33. Trochlear dysplasia- Dejour’s Classification Type B
- 34. Trochlear dysplasia- Dejour’s Classification Type C
- 35. Trochlear dysplasia- Dejour’s Classification Type D
- 36. Treatment Aim : •Decrease swelling and relieve pain •Promote vastus medialis and and gluteal activity •Painfree ROM •Address the pathoanatomy causing dislocation Conservative/Operative
- 37. Treatment: Acute Dislocation Conservative: • Immobilisation- Controversial • Aspiration of hemarthrosis • Ice comepression intermittently • Quadriceps and gluteal exercises • Crutches discontinued and able to bear weight and walk after 3-5 days • Rehabilitation continued and return to sports activity once 85% quads and hams strength attained
- 38. •Surgery indicated for: • Associated large osteochondral fractures • Loose body or joint incongurity • Competitive athletes with high level activity •MPFL repair vs reconstruction + VMO repair Treatment: Acute Dislocation
- 39. Treatment: Recurrent Dislocations Conserevative • Immobilize in a brace with jones compressive bandaging • Quadriceps set exercises and straight leg raises
- 40. Surgery •Failed conservative management in •active, surgically fit individuals •Surgery needed to prevent joint deterioration Treatment: Recurrent Dislocations
- 41. •No single universal surgical procedure •Choice of surgery depends upon • Pathological anatomy • Patient demand • Skeletal maturity •Arthroscopic inspection of articular surface and intra-articular structures Surgical treatment
- 42. •Operative- More than 100 surgical procedures described • Lateral Release • Medial repair • MPFL reconstruction • Trochleoplasty • Proximal Realignment Procedure • Distal Realignment Procedure Surgical treatment : Options
- 43. Lateral release •Indication : • Negative patellar tilt • Less than one quadrant medial patellar glide •Open/Arthroscopic •Never done alone, always combined with some other procedure
- 44. MPFL Reconstruction •Autograft/allograft • Gracilis • Semitendinosus •Adequately tensioned •Physiometric postion- confirmed clinically and radiographically
- 47. MPFL reconstruction: Superficial Quads Technique
- 49. Proximal Realignment Procedures •Usually done for skeletally immature individuals •Lateral retinaculum and capsule released •Quadriceps tendon split and sutured to patella Insall Procedure
- 50. Distal Realignment Procedures •Instability due to malalignment(Q angle >20) •TT-TG distance >20mm •Soft tissue procedure Roux-Goldthwait Procedure Galleazi Procedure
- 51. Distal Realignment Procedures Bony procedure : Elmslie-Trilaat Procedure • Lateral retinacular release • Medical retinacular plication • Medial transfer of the tibial tuberosity
- 52. Oblique Osteotomy of the Tuberosity
- 53. Distalization of Tibial Tuberosity For Patella Alta
- 54. Derotational high tibial osteotomy •For condtions with high degree of rotational deformity •Thigh foot angle > 30 degrees or tubercle sulcus angle >10 degrees
- 56. What’s New? Vivek Jha, Prathmesh Jain,Medial Patellofemoral Complex Advancement for Recurrent Lateral Patellar Instability and Selective Acute Primary Patellar Dislocations,Arthroscopy Techniques,Volume 10, Issue 3,2021,Pages e767-e774,ISSN 2212-6287.
- 57. What’s New? Seitlinger G, et al, Tibial tubercle-posterior cruciate ligament distance: a new measurement to define the position of the tibial tubercle in patients with patellar dislocation. Am J Sports Med. 2012 May;40(5):1119-25.
- 58. Take Home Message Patellar instability occurs due to inequality in tension between medial and lateral structures. MPFL reconstruction is the key procedure for restoring medial tensio,. Lateral forces can be offloaded by shifting tibial tubercle medially and anteriorly. Trochleoplasty is reserved for those with severe dysplasia
- 59. REFERENCES : Campbell’s Operative Orthopaedics , 13th Edition Apley and Solomon’s System of Orthopaedics , 10th Edition Dejour, D.H., Mesnard, G. & Giovannetti de Sanctis, E. Updated treatment guidelines for patellar instability: “un menu à la carte”. J EXP ORTOP 8, 109 (2021). https://doi.org/10.1186/s40634-021-00430-2 Goyal D. Medial Patellofemoral Ligament Reconstruction: The Superficial Quad Technique. The American Journal of Sports Medicine. 2013;41(5):1022-1029. doi:10.1177/0363546513477828
- 60. Thank You
Editor's Notes
- Divided into smaller medial and larger articular surface or facet Medial and lateral facets each further divided into 3 – superior, middle and inferior and a 7th the most medial known as odd facet
- The primary function of the vastus medialis obliquus muscle is to stabilizethe patella against the lateral pull of the vastus lateralis,making the vastus medialis obliquus the dynamic stabilizer of the patella.
- The primary function of the vastus medialis obliquus muscle is to stabilizethe patella against the lateral pull of the vastus lateralis,making the vastus medialis obliquus the dynamic stabilizer of the patella.
- Extension- only the lateral facet articulates with the lateral femoral condyle 45 degree, contact moves proximally to the midpoint of articular surface Complete flexion, proximal portions of both facets in contact with femur Total excursion 7-8 cm during flexion- extension
- Intersection of line drawn from asis to centre of patella and another from centre of patella to tibial tuberosity Knee flexed 30degree
- Wiberg I roughly equal medial and lateral facets\ II medial facet half the size of lateral, m/c III medial facet is so far medial that the vertical ridge is rarely visible
- Genu valgus Increased femoral anteversion External tibial torsion Lateralisation of tt
- Dynamic patellar tracking is evaluated with the examiner standing in front of the seated patient while the patient slowly extends the knee. A positive J sign (slight lateral subluxation of the patella as the knee approachesfull extension) indicates some degree of maltracking
- Measure q angle at supine and at 30 degree knee flexion
- For the “apprehension test,” the examiner holds the relaxed knee in 20 to 30 degrees of flexion and manually subluxes the patella laterally. When the test is positive, the patient suddenly complains of pain and resists any further lateral motion of the patella (Fig. 47-2)
- For the “apprehension test,” the examiner holds the relaxed knee in 20 to 30 degrees of flexion and manually subluxes the patella laterally. When the test is positive, the patient suddenly complains of pain and resists any further lateral motion of the patella (Fig. 47-2)
- Total score 9 Score of 4 or more is suggestive of generalized hyperlaxity
- The foot progression angle (FPA) is defined as the angle between the line from the calcaneous to the second metatarsal and the line of progression averaged from heel strike to toe off during the stance phase of walking for each step (toe-in angle is positive and toe-out angle is negative).
- Bipartite patella Osteochondral defects
- Line along the roof of intecondylar notch should lie along the inferior pole of patella in 30 degree knee flexion
- Insall and Salvati found that the length of the patellar tendon (LT) and the diagonal length of the patella (LP) had a ratio of 1.0 (Fig. 47-4), with less than 20% variation. Ratio between articular facet length of patella (AP) and distance between articular facet of patella and anterior corner of superior tibial epiphysis (AT). Knee flexed 30 degrees. Blackburne and Peel described a similar ratio of the length of the articular surface of the patella to that of the length measured from the articular surface of the tibia to the inferior pole of the patella. They suggested that these landmarks can be seen and reproduced more easily on radiographs. Normal ratios with this measurement were between 0.54 and 1.06.
- When the axial view has been obtained, the shape of the patella should be evaluated, along with the shape of the femoral trochlea and the relationship of the patella to the femur. Normally, the patella appears evenly seated within the trochlear groove of the femur, with an equal distance betweenboth patellar facets and the adjacent femoral surfaces. Abnormalities include tilting of the patella or subluxation and complete dislocation of the patella (Fig. 47-8). The trochlea is evaluated on the Merchant view for dysplasia, sulcus angle greater than 145 degrees, and congruence, normally 60―
- Sulcus angle- 138+/-7, >145 suggests dysplasia Conglunce angle -8+/- 6, >16 indicates excessive ateral displacewment
- Angle formed by intersection of the tangent of the posterior condyles and the major axis of the patella on 20-degree flexion scan
- Bicondylar line along the posterior femoral condyles, two line perpendicular to it, one through the trochlear groove and the other through the tibial tuberosity
- Angle formed by intersection of the tangent of the posterior condyles and the major axis of the patella on 20-degree flexion scan
- The trochlear depth measurement is performed on a true lateral radiograph view. A tangent to the posterior femoral cortex (red line) and a perpendicular line at the most proximal part of the posterior condyles (blue line) are drawn. A (yellow) line subtended 15° from the perpendicular line is now used to measure the trochlea depth (AB length). MRI: The method introduced by Pfirrmann measures the distance of the trochlear groove and the medial and lateral trochlear facets to a tangential line of both femoral condyles. To calculate trochlear depth the distance from the trochlear groove from the before mentioned tangent is subtracted from the average of the two distances between the medial and lateral facet and that tangent 2. The measurement was conducted at different levels above the knee joint and found most useful at 3 cm above the joint line.
- crossing sign is present on true lateral view; trochlea is shallower than normal, but still symmetric and concave The crossing sign is seen on true lateral plain radiographs of the knee when the line of the trochlear groove crosses the anterior border of one of the condyle trochlea.
- crossing sign and trochlear spur; trochlea is flat or convex in axial images.
- Type C: crossing sign plus double-contour sign representing sclerosis of the subchondral bone of the medial hypoplastic facet; on axial CT views, lateral facet is convex
- Type D: combination of all signs—crossing sign, supratrochlear spur, and doublecontour sign; cliff pattern on axial CT views..
- Immobilise in a brace with jones compressive bandaging Aspiration of hemarthrosis sterile, if causing significant pain and tightness Quadriceps set exercises and straight leg raises Ice comepression intermittently Crutches discontinued and able to bear weight and walk after 3-5 days Rehabilitation continued and return to sports activity once 85% quads and hams strength attained
- Abnormal patellofermoral articulation Abnormal quadriceps pull/mechanism Chondromalacia of patella Osteochondral fractures/fragments Menisceal tear and degeneration All contribute to progressive deterioration of knee joint
- effective lateral release must include release of the retinaculum from the distal third of the vastus lateralis femoral and patellotibial ligaments. Most procedures for patellar realignment include release of the thickened and contracted lateral retinaculum when it prevents centering
- Schottle and colleagues’ radiographic landmark for femoral tunnel placement in medial patellofemoral ligament reconstruction. Two perpendicular lines to line 1 are drawn, intersecting the contact point of the medial condyle and posterior cortex (point 1, line 2) and intersecting the most posterior point of the Blumensaat line (point 2, line 3). For determination of vertical position, distance between line 2 and the lead ball center is measured as is the distance between line 2 and line 3.
- Arthroscopically examine the knee through standard medial and lateral portals to evaluate patellar tracking and look for intraarticular damage and evaluate patellar tracking. This evaluation is essential for determining appropriate treatment. Make a 3-cm incision 3 cm medial to the inferior portion of the patellar tuberosity and harvest the semitendinosus tendon in standard fashion. Size the folded graft so that the appropriately sized tunnel can be reamed later. Place a 0 Vicryl Krakow suture in each tail of the semitendinosus Make two 2-cm incisions, the first just medial to the superior border of the patella and the second starting at the adductor tubercle and extending just distal to the medial epicondyle of the femur, to expose the patellofemoral ligament. Stay between the MPFL and the capsule and stay extrasynovial to pass the looped sutured graft into the soft tissue tunnel Graft anchored to the patella with help of suture anchors Pull the graft taut, and stress the patella so as to allow for one to two quadrants of lateral passive glide. When the physiologic amount of tension on the graft is determined, make a mark on the graft, which will correspond to the aperture of the femoral tunnel Place absorbable whip sutures in the tails of the graft (Fig. 47-15D), place them into the tip of a Beath pin, and pull them out laterally (Fig. 47-15E
- First described by Steensen et al and Albright et al independently in 2005 and 2006 respectively. Revived by Deepak goyal in
- As in fig C oblique osteotomy from antermoedial to posterolateral direction can lift the tuberosity Stress risers and sterss fractures Hence not suitable for athletes and suitable for those with high grade chondromalacia and degenerative changes