Patella dislocations

Patella dislocations
Patella anatomy
Wiberg classification
Attachments around patella
Patello-femoral articulation
Patella femoral contact points
Joint reactive force
Patello femoral stabilizers
Static stabilizers
Dynamic stabilizers
Cause of patella instability
Mechanism of injury of Patella dislocations
Patella alta
Trochlear dysplasia
Apprehension test
Q angle
Axial views for patella
Blumensaat's line
Quadriceps training
Mc Connell patella taping
Recurrent Patellofemoral dislocation management
Medial patello foral ligament reconstruction
Graft source
Schottle's point
Appropriate tensioning
Medial repair
Nam and Karzel
Distal Realignment surgeries
Elmslie-Trillat operation
Fulkerson Operation
Trochlear dysplasia
Trochleoplasty
Derotational high tibial osteotomy

1. Patellar Dislocations By Dr Kota Gandhi I yr PG Orthopaedics Kamineni Institute Of Medical Sciences

2. The patella is a flat, triangular bone, situated on the front of the knee-joint. It is usually regarded as a sesamoid bone, developed in the tendon of the Quadriceps femoris . Anatomy

3. Anatomy The upper three quarters of the patella articulates with femur and subdivided into medial and a lateral facet by vertical ledge which varies in shape. Wiberg classification is a system for describing the shape of the patella based mainly on asymmetry between the patellar medial and lateral facet on axial views of the patella. Type I: the facets are concave, symmetrical, and of equal size. Type II: the medial facet is smaller than the lateral facet and flat or only slightly convex. The lateral facet is concave. Type III: the convex medial facet is markedly smaller than the concave lateral facet, and the angle between the medial and lateral facets is nearly 90°.

4. Rectus femoris tendon : 8 -10 cm in length, triangular in shape with insertion 3-5 cm in width at superior pole of patella. VMO tendon : Inserts obliquely at superomedial border of patella only a few mm in length; primary stabiliser of patella medially against VL Vastus Lateralis : Inserts obliquely At superior lateral aspect of Patella, 2.8 cm in length Lateral expansion of Vastus Lateralis With a superficial and deep layer Forms the Lateral retinaculum ; Deep layer is the lateral patellofemoral ligament : this is a static guide for the patella; this may decrease medial excursion and increase the lateral tracking. Medial side also has a patellofemoral ligament but it is much weaker than lateral side. Attachments around Patella

5. The Patello-Femoral joint Is a complex structure with high functional and bio mechanical requirements. The normal function of this joint is dependent on the congruent relationship of the patella with the trochlear groove.

6. No contact between the femur and patella in full extension. From extension to flexion, the patella begins laterally and moves medially as the patella enters the trochlear groove and tibia derotates. With flexion, patella enters the trochlear groove from the lateral side Seats in the trochlear at ~20 degrees at this point the congruence and compressive forces provide stability From 0 – 20 degrees, stability comes from soft tissues. Patello-Femoral Articulation

7. Variations in area of contact: Inferior Surface – first contacts at 20 degree flexion Mid Portion – 60 degree flexion Superior portion – 90 degree flexion Extreme flexion (> 120 degrees) – only medially and laterally, quadriceps tendon articulates with trochlea Patella femoral contact points

8. In flexion patella compressed onto femur creating joint reactive force . Directly related to quadriceps force generation . Increases as the angle of flexion increases . Joint reactive force

9. Static stabilizers Trochlear groove: primary bony stabilizers depth , height and engagement Medial patellofemoral femoral ligament primary static soft tissue stabilizer Medial retinaculum Dynamic stabilizer Quadriceps (VMO) Patello femoral stabilizers

10. Soft Tissue Global --HMS ( Hyperlaxity ) Medial MPFL Insufficiency VMO dysplasia/VL dominance Lateral -- ITB, Contracture Lat Ret Osseous abnormalities Patella alta/ morphology Trochlea dysplasia Lower limb Malalignment (Torsion or Genu Valgum ) Fem anteversion , Ext tibia torsion, foot pronation Increased Q angle or TT:TG distance Gait (Valgus thrust, Pelvis core muscles) CAUSES OF PATELLA INSTABILITY

11. Mechanism Of Injury

12. Acute Dislocation Single episode after a significant trauma. Almost always lateral dislocation Recurrent Dislocation repeated, occasional dislocation (commonest form). The dislocations may occur at intervals of weeks or months. Habitual Dislocation also known as chronic dislocation patella which dislocates every time the knee flexes. In these cases it cannot be held in the reduced position throughout the full range of flexion. Types of dislocations Recurrent Dislocation • Second decade • Female preponderance / Athletic males • Initial episode of dislocation • Subsequent episodes of instability • Frequency decreases with Age(Crosby) • The main factor is incompetence of MPFL Habitual Dislocation • Knees in which patella dislocates laterally each time knee is flexed and returns to midline in extension(Habitual dislocation) • More severe —patella permanently dislocated —(Permanent dislocation)

13. • Young • Female • Family history • Bilateral • Atraumatic disorders • Anatomic abnormalities P atella alta Trochlear hypoplasia TT-TG distance ‘ Q’ angle Q uadriceps dysfunction H yper mobility Predisposing factors responsible for recurrence

14. Evaluation We evaluate the following features Integrity of medial patello femoral ligament Height of patella on physical and radiographic examination Length of patellar tendon Position of patella in relationship to trochlea

15. A patella alta , or high-riding patella, is a patella that is too high above the trochlear fossa and occurs when the patellar tendon is too long. Patella alta is considered a main factor in patellofemoral misalignment because with patella alta, the degree of flexion needs to be higher for the patella to engage in the trochlea, compared with a normal knee. This problem leads to reduced patellar contact area and decreased bone stability in shallow degrees of flexion. About 25% of the patients with acute patellar dislocation have a high-riding patella depicted on MR images. Note, however, that patella alta is a normal anatomic variant that is asymptomatic in most individuals. Patella Alta

16. 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 degree Trochlear dysplasia has been identified as one of the main factors contributing to chronic patellofemoral instability. Trochlear dysplasia

17. 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. It is a predictor of trochlear dysplasia. Trochlear dysplasia has been linked to recurrent patellar dislocation . The crossing sign is sensitive but not specific in diagnosing trochlear dysplasia, and has a sensitivity of 94% and a specificity of 56%

18. The double contour sign is a helpful radiologic sign which is seen on true lateral plain radiographs of trochlear dysplasia. A double line at the anterior aspect of condyles that seen if medial condyle is hypoplastic . Trochlear spur The supratrochlear spur corresponds to an attempt to contain the lateral displacement of patella

19. 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 hypo plastic medial facet Type D: type C features and a vertical link between facets ('cliff pattern') 3 Classification of trochlear dysplasia ( Dejour et al)

20. Fairbanks patellar A ppre h ension tes t , when positive (pain and muscle defensive contraction on lateral patellar displacement with 20˚ to 30˚ of knee flexion), indicates that lateral patellar instability is an important part of the patient’s problem. This test may be so positive that the patient withdraws the leg rapidly when the examiner approaches the knee with his or her hand, preventing thus any contact, or he or she grabs the examiner’s arm.

21. Patellar tilt test can also detect a tight lateral retinaculum , and should always be carried out . In a normal knee, the patella can be lifted from its lateral edge farther than the transepicondylar axis, with a fully extended knee. On the contrary, a patellar tilt of 0˚ or less indicates a tight lateral retinaculum . Lateral retinacular tightness is very common in patients with anterior knee pain, and it is the hallmark of the excessive lateral pressure syndrome described by Ficat .

22. Patellar tracking should be examined using the “J” sign . With the patient seated on the examination table with the legs hanging over the side and the knees flexed 90˚, he or she is asked to extend the knee actively to a fully extended position. Normally, the patella follows a straight line as the knee is extended. However, as the knee is extended the patella runs proximally and laterally describing an inverted “J” when patellofemoral malalignment (PFM) is present.

23. We perform the patellar glide test to evaluate lateral retinacular tightness. This t est is performed with the knee flexed 30˚, and the q uadriceps relaxed. The patella is divided into four longitudinal quadrants. The patella is di splaced in a medial direction. A medial translation of one quadrant or less is suggestive of excessive lateral tightness.With this test pain is elicited over the lateral retinaculum .

24. Q angle described by Sir Brasttstrom Increase d in genu valgum , external tibial torsion, increase femoral anteversion , laterally positioned tibial tuberosity and tight lateral retinaculum . Increase Q angle : more chance of recurrent subluxation Normal Q angle in males 8 -10 degrees and in females 15 +/- 5 degrees

25. Imaging of the patellofemoral joint AP and lateral knee x ray Axial - Merchants view and Laurin view MRI axial view CT rotational profile

26. The knee skyline Merchant view   is a superior-inferior projection of the patella it is one of many different methods to obtain an axial projection of the patella. This is an ideal projection for patients that are better suited in the supine pos ition . The knee skyline Laurin view  is an inferior-superior projection of the patella. It is one of many different methods to obtain an axial projection of the patella. This projection is best suited to patients able to maintain a semi-recumbent position on the examination table. Axial views for Patella

27. Lateral views for Patella

28. Normal 0.54-1.06 >1.2 patella alta <0.8 patella ba ja

29. CT Significant advantage -Avoids problems associated with positioning, obesity etc -Avoid image overlap and distortion Look for -Sulcus angle, tilt, congruence, femoral trochlear depth and subluxation

30. Congruence Angle

31. C T classification of malalignment T ype 1 - lateral subluxation with out tilt T ype 2 - lateral subluxation with tilt Type 3 - lateral tilt without subluxation Type 4 - radiographically normal alignment

32. MRI Scan MRI can be used to diagnose prior patellar dislocations on the basis of typical injury patterns. In general, deformity or deems of the inferno medial patella and the lateral condyle, in conjunction with MPFL disruption and patellar lateralisation, is diagnostic for recent patellar dislocation More than two-thirds of the patients will show osteo-chondral lesions of the medial patella.

33. Management • Non Operative management To be attempted in all patients. • Goals —Normal flexibility,Balanced quadriceps strength,Stretching of tight lateral structures • Push back w/o difficulty . • Jt aspiration and immobilized in full extension for 3 weeks. >Splint; • If no sign of soft tissue lesion • Retained for 2-3 weeks • Quadriceps strengthening exercise ; 2-3 months.

34. 1.Quadriceps strengthening 2.Core stability 3.Mc Connell taping 4.Insoles Treatment of Patella Instability Always conservative first

35. Quadriceps Training 1.Most Essential component 2.Strengthening of quadriceps especially VMO 3.Isometric and progressive resistance exercises with knee in extension 4.With increasing strength short arc exercises in last 30°.

36. Indications With certain knee injuries – such as patellofemoral pain syndrome where abnormal patella tracking is contributing to the injury. To prevent injury or injury aggravation – Patella taping maybe beneficial during sports or activities that place the knee at-risk of injury or injury aggravation Mc Connell patella taping

37. Barefoot running Barefoot running may reduce patellofemoral joint stress as a result of reduced joint reaction forces. Barefoot runners are more likely to use it forefoot versus a heel strike Pattern in the initial loading response, which has been shown to increase ankle eccentric work and simultaneously decrease the loading on the knee joint

38. Surgical treatment Surgery in acute patella dislocation is indicated in Osteochondral fracture Loose body formation or joint incongruity Incompetency of MPFL Removal of loose bodies and MPFL repair required in these conditions. Complications Recurrent dislocation Anterior knee pain Knee swelling Recurrent haemarthrosis

39. Recurrent Patellofemoral dislocation management If dislocation of the patella continues despite appropriate nonoperative treatment, surgery is indicated. Otherwise, the patient may become apprehensive and afraid to use the knee, and with continued recurrence the joint may be severely damaged. More than 100 surgical procedures have been described for the treatment of patellofemoral instability. The key to successful surgical intervention is correctly identifying and treating the pathologic anatomy producing the instabi lity .

40. The surgical procedures for recurrent Patellar instability are classified into proximal and distal realignment The operation involving structures above the knee cap are termed as Proximal and if involves structures below are termed as Distal. Proximal realignment of extension mechanism MPFL reconstruction Lateral retinacular release Medial plication / reefing VMO advancement Distal realignment of extensor mechanism 1. Medial or antero medial displacement of tibial tuberosity

41. 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. Medial Patello femoral ligament Reconstruction

42. I ndicated in : skeletally mature patient excessive lateral laxity normal trochlea ‘ Q ' angle is normal TT-TG distance is < 20mm low grade trochlear dysplasia Contraindications : skeletally immatur ity Medial Patello femoral ligament Reconstruction

43. Examination under anaesthesia (EUA) Diagnostic Arthroscopy: Superolateral portal Graft Harvest & preparation Incission 1: on medial side patella Incission 2: on femoral fixation site Patellar side fixation Graft passage from incision 1 to 2 Femoral side fixation Appropriate tensioning Surgical Steps

44. Gracilis (G): stiffness closer to MPFL Semitendinous (ST) Medial patellar tendon (PT) Adductor tendon (AMT) Quadriceps tendon (QT) Allografts Artificial tendons One end of the graft may be left attached; ex: ST tibial attachment, AMT femoral attachment, QT patellar attachment Graft source

45. Graft is passed extracapsularly from incision 1 to incision 2 Reference for fixation on Femur : Anatomic: from the medial femoral epicondyle, 10 mm proximal and 2 mm posterior from the adductor tubercle, 4 mm distal and 2 mm anterior. Flouroscopic : On true lateral view of the knee.

46. A line is drawn extending distally from the posterior femoral cortex (line 3). Two lines are drawn perpendicular to line 3, the first intersecting the point where the margin of the medial condyle meets the posterior cortex (line 1) and the second intersecting the most posterior point of Blumensaat's line (line 2). A circle of 5-mm diameter is drawn contacting the line drawn from the posterior cortex. The MPFL femoral insertion should fall within this circle. Schottle’s point

47. Place the pin at Schottle's point. Drill the Beath pin to lateral side ( more anterior and proximally) Drill 4mm tunnel through; dilate according to graft size and length ( usually 25mm long, 6 rum diameter) Pass suture on heath pin to lateral side Pull the graft ends in to the tunnel. Put the nitenol wire for screw insertion before whole graft goes in; otherwise finding the tunnel to put screw will be difficult. Put appropriate size screw flush to the cortex.

48. Appropriate tensioning The ideal tension at the time of fixation of the graft is unknown. The ligament functions as a check rein in early flexion (o to 3o degrees) and is therefore under the greatest tension in this range of knee flexion. It is logical to fix the graft with the knee at 3o to 4o degrees flexion. The patella should not be pulled medially by the reconstructed ligament but lateral translation beyond the lateral margin of the trochlear should be prevented.

49. Prominence of fixation hardware on the medial aspect of the medial femoral condyle: local irritation and potentially restrict motion Patellar fracture: usually relates to the use of bone tunnels; penetration of the anterior cortex Recurrent lateral patellar dislocation: predisposing factors such as patellar alts, trochlear dysplasia, and lateralization of the tibial tuberosity, as well as the overall alignment of the lower limb Infection Hematoma formation Graft site morbidity Complications

50. I ndication 1)Tight lateral structure prevent patellar centring 2)Lateral patellar pressure syndrome  3)Can be done in skeletally immature patients  Re lease to include 1) Lateral retinaculum from distal third of vastus lateralis   2)Lateral patellofemoral ligament  3)Lateral patellotibial ligament Lateral Release

51. Can be done open or arthroscopy procedure ( now a days arthroscopic release preferred ) C omplications 1 )Extending the release too far can cause medial subluxation of the patella; infact medial patella subluxation or dislocation is almost always iatrogenic, secondary to an overzealous lateral release.  2)injury to superolateral geniculate vessel to prevent this make a superior anterolateral 2cm incision starting just lateral to the proximal pole of patella.  Results varied, good results in short term( metcalf,Simpson ),poorer in long term(Christensen)

52. Anatomical and biomechanical studies have indicated that the MPFL and the VMO are the primary restraints to lateral patella translation, particularly early in flexion before full trochlear engagement.  There are 3 types of primary procedures for medial repair the techniques include  P lication of the medial patellar retinaculum . Anatomic repair of the MPFL, and  Anatomical repair surgery of the VMO. Medial Repair

53. Technique -make a 4cm incision at the superior pole of patella,2cm medial and parallel to the medial border of patella extending distally.  -identify the vastus medialis and medial retinaculum , grasp these structure and pull them laterally to asses the integrity of adductor tubercle attachment site.  -carefully incise the vastus medialis and medial retinaculum along the medial border of patella down to, but not through,the level of synovium .  -using no.2 ethibond suture, advance the medial retinaculum to the medial border of patellausing atleast four mattress suture.

54. Medial reefing and lateral release NAM AND KARZ EL ■ Perform a mini open medial reefing procedure. Make a 4-cm incision, starting at the level of the superior pole of the patella, 2 cm medial and parallel to the medial border of the patella extending distally. Carry dissection down through the subcutaneous tissues. ■ Identify the vastus medialis and medial retinaculum and carefully inspect for any areas of detachment. Grasp these structures with a clamp and manually pull them laterally to assess the integrity at the adductor tubercle attach- ment site. ■ Continue lateral advancement to the patella. Carefully incise the vastus medialis and medial retinaculum along the medial border of the patella down to, but not through, the level of the synovium . ■ Using no. 2 nonabsorbable , braided polyester suture, advance the medial retinaculum to the medial border of the patella using at least four mattress sutures. ■ Before the sutures are tied, assess range of motion to determine congruent tracking of the patella and to ensure at least 90 degrees of knee flexion. ■ Reintroduce the arthroscope to confirm centralization of the patella within the trochlear groove, and increase or decrease the suture tension as necessary. ■ Tie the sutures with the knee in full extension, and close the incision in a standard fashion.

55. Medial reefing and lateral release NAM AND KARZEL

56. Distal Realignment Surgeries A ims to diminish the Q angle or TT-TG distance with anteromedialisation of tibial tuberosity and unloads patello femoral articulation . Indications Q angle or /1" TT-TG distance > 20mm Patellar alta Normal patellar glide Medial facet arthritis Contraindications 1. Skeletally immature patients 2. incompetent MPFL 3. Diffuse patellar arthritis

57. ELMSLIE-TRILLAT OPERATION

58. FULKERSON OPERATION

59. Surgical 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 done Contra indications Skeletally immature patients Associated osteoarthritis Management of Trochlear dysplasia

60. Type A dysplasia : medial patellofemoral ligament reconstruction Type B and D dysplasia : sulcus deepening trochleoplasty with MPFL reconstruction Type C dvsplasia : lateral facet elevation trochleoplasty with MPFL reconstruction Management of Trochlear dysplasia

61. Trochleaoplasty

62. Derotational High tibial osteotomy INDICATIONS 1)Femoral ante version(thigh foot angle>30 degree) 2)External tibial torsi on 3)Tubercle sulcus angle angle more than 10 degree.

63. Thank You!