Acl reconstruction

Acl reconstruction

1. Anterior cruciate ligament injury Dr.PONNILAVAN

2. ANATOMY

3. ANATOMY ACL is a band of dense connective tissue that connects the femur and the tibia. Enveloped by the synovial membrane Intraarticular but extra-synovial

4. EMBRYOLOGY

5. HISTOLOGY Made of multiple collagen fiber bundles Major cell type – fibroblast 65–75% of lig . Wt. composed of water Type 1 collagen (80%) Type 3 collagen(<20%)

6. The Chondral apophyseal enthesis is present in femoral & tibial insertions Mostly elongated fibroblasts except in distal third of ACL Due to “physiological Impingement”– presence of Chondrocytes like cells is a functional adaptation to the compressive stress 4 Layers : Ligament fibres Non- mineralised cartilage zone Mineralised cartilage zone Subchondral bone plate

7. BLOOD SUPPLY PROXIMALLY - middle geniculate artery. DISTALLY - lat. and med. branch of inferior geniculate artery Proximal and distal vessels support a synovial plexus from which small vessels runs parallel into the collagen bundles.

8. ACL (measurements) Length 32 mm (22-41 mm ) Width 10 mm (7-12 mm ) Midsubstance cross- section “ irregular ,” “ oval ,” “ corded ,” or “ bundled ” Midsubstance - diameter 36 mm² ( f) & 44 mm² ( m) . Tibial and femoral insertion was > 3.5 times larger than midsubstance

9. NERVE SUPPLY Subsynovial layer and near ACL insertions 2 types of receptors- RUFFINI: STRETCH receptor. FREE NERVE ENDING : NOCICEPTOR Electromyographic studies show receptors respond to knee extension Nociceptor  Vasoactive neuropeptide– enhances graft healing Positive correlation between the number of mechanoceptors and the accuracy of joint position sense in the remaining ACL stump

10. The axis of the long diameter of the ACL is tilted 26°+/- 6° forward from the vertical lateral spiral arrangement. This external rotation is app. 90° Orientiation of attachments: Femur- longitudinal axis Tibia - Transverse axis PHYSIOLOGICAL IMPINGEMENT : The ACL tibial attachment fans out and forms a “foot” region. This allows the ACL to tuck under the roof of the intercondylar notch. In full extension the anterior fibers of the ACL turn around the anterior edge of the intercondylar notch ACL graft (BPTB/Hamstring) do not posses such “foot” region and orientiation Notch impingement

11. Intercondylar Notch Wide –posterior ; narrow – anterior Narrow in females Notch Width Index (NWI) – ratio of epicondylar width to notch width “Gothic shape”-intercondylar fossa and the roof is called Blumensaat line. Notch roof angle = 23 to 60 degrees Small roof angled knees called “Non Forgiving Knees”- Tibial tunnel placement is critical .

12. BUNDLE THEORIES OF ACL Differentiation into bundles is controversial. Odensten et al : histologically found no evidence of separation Girgis et al : 2 bundles, ( AM and PL ) Amis et al : 3 bundles, ( AM , intermediate and PL bundle. Amis AA, et al : Functional anatomy of the ACL. JBJS Br73:260-267, 1991 Odensten M,et al : Functional anatomy of the ACL and a rationale for reconstruction. JBJS 67A:257-262, 1985 Girgis FG, et al : The cruciate ligaments of the knee joint. Anatomical, functional and experimental analysis. Clin Orthop 106:216-231, 1975

13. R.Siebold et al., Anterior Cruciate Ligament Reconstruction, ESSKA 2014 “ double-bundle effect ” was created by the twisted flat ribbonlike structure of the ACL from femoral to tibial, which leads to the impression of two or three separate bundles when the knee was flexed.

14. MECHANICAL PROPERTIES OF ACL Tensile load : 2,160 N Stiffness : 242 N/mm Forces in the intact ACL: 100 N during passive knee extension 400 N on walking ̰ 1,700 N with cutting and acceleration-deceleration activities.

15. BIOMECHANICS Length and orientation changes throughout flexion and extension as well as tibial internal and external rotation.

16. Variations in the length of ACL Distances between origin and attachment of the ACL fibers vary with motion Takai et al. - 3.3 mm Hollis et al. - 3.9 mm AM PL 1.5 mm 7.1 mm On 90 deg flexiom Hefzy and Grood et al. Fiber length is affected more by varying the femoral attachment. Moving the tibial location had only a small effect;

17. Functional rationale 1° restraint for ant. Tibial translation 2° restraint to tibial rotation on wt.bearing knee or valgus / varus stress

18. FEMORAL FOOTPRINT original studies : ACL attachment in narrow oval area in LFC Recent studies: described ACL attachment in wide area on the LFC

19. FEMORAL FOOTPRINT In the lower third of inner wall of LFC, Inferior to the lateral intercondylar ridge .

20. SHAPES OF FEMORAL FOOT PRINT CIRCULAR ELLIPTICAL KIDNEY- SHAPE SEGMENT OF CIRCLE SEGMENT OF ELLIPSE TRAPEZOIDAL OVAL TRIANGULAR OTHER: (fits none) MAX KONSTANTIN ZAULECK et al: Origin of the ACL and the Surrounding Osseous Landmarks of the Femur Clinical Anatomy 27:1103–1110 (2014)

21. Sebastian Kopf Size Variability of the Human Anterior Cruciate Ligament Insertion Sites Am J Sports Med 2011 39 There is large variation in size of the ACL insertion sites and the AM and PL bundles There is no correlation between the size of the insertions and height, weight, and body mass index of the individual patient .

22. ACL femoral tunnel can be located intraop by: 1. Native ACL footprint 2. Lateral intercondylar and bifurcate ridges 3. ACL ruler method 4. Intraoperative fluoroscopy ( grid method ).

23. REASONS FOR PRESERVING ACL STUMP Guide for the tunnel placement. Increased mechanical strength in the early postoperative period Preservation of the blood supply, which may aid in the healing process of the graft Maintenance of proprioception

24. Femoral ridge method 1.7 mm deep to the bifurcate ridge 7.3–8.5 mm high or anterior to the posterior articular cartilage of LFC

25. ACL RULER METHOD knee is flexed to 110° length of the ACL femoral attachment site is measured along its long axis The ACL ruler is inserted angled microfracture awl inserted at 50 % mark

26. Bernard-Hertel grid method - measurement along Blumensaat’s line - the height of the intercondylar notch

27. Bernard- Hertel grid ACL attachment site is located at: 27 % along Blumensaat’s line 34 % of the height from the intercondylar notch

28. Bernard- Hertel grid ( Intraoperative fluoroscopic image)

29. Bernard- hertel grid method ( ACUFEX Smith & Nephew, Director Application Anatomic Guide software ) can be used to plot the Bernard and Hertel grid from the intraoperative c-arm image

30. Femoral tunnel Steiner et al recommended that “ the femoral tunnel be placed at the centre of the femoral footprint , although he recommended that the tibial tunnel be placed at the AM footprint”.

31. POST OP TUNNEL POSITION ASSESMENT ( AP Xray ) Femoral tunnel angle relative to the long axis of the femur Angle > 32° is suggestive of anatomic tunnel placement

32. C, J, CC INSERTIONS IN TIBIA Śmigielski R (2012) The ribbon concept of the ACL. ACL Study Group Meeting.

33. Landmarks for Tibial footprint Anterior border of the PCL Posterior border of the anterior horn of the lateral meniscus. Interspinous area of the tibial plateau Retro–eminence ridge Transverse ligament

34. Tibial acl anatomy 1. In line with ant. horn of lat. meniscus 2. Anterior to insertion of PCL

35. ACL tibial footprint Ziegler et al 7.5 mm medial to the anterior horn of the lateral meniscus 13.0 mm anterior to the retro-eminence ridge 15.7 mm anterior to the PCL Kong charoensombat et al transverse ligament coincides with the anterior edge of the ACL tibial footprint in the sagittal plane

36. ACL Tibial footprint Ferretti 9.1 ± 1.5 mm posterior to the intermeniscal ligament 5.7 ± 1.1 mm anterior to apex of the medial tibial eminence Morgan (MRI study) 7 mm anterior to the anterior margin of the PCL with the knee flexed at 90° Hutchinson Center of ACL is 10.4 ± 2.4 mm anterior to the PCL Posterior border of the ACL tibial footprint is 6.7 ± 1.2 mm anterior to PCL

37. Intra op Tunnel position assesment In AP view , the pin should emerge on the down slope of the medial tibial spine In lateral view , the pin should be at the junction of anterior and middle third of the tibial plateau In extension (lateral view), the pin should be posterior to extension of the Blumensaat line

38. How ACL is torn???

39. Direct contact or collision, such as a football tackle contact injuries

40. Higher incidence of ACL injury than men because of Differences in Anatomical disparities Muscular strength Neuromuscular control pelvis and lower extremity alignment the effects of estrogen on ligament properties(?)

41. Changing direction rapidly Stopping suddenly Slowing down while running Landing from a jump incorrectly Non contact injuries

42. ACL RECONSTRUCTION EXTRA-ARTICULAR-(iliotibial band tenodesis and bicepsplasty ). MacIntosh Losee Andrews INTRA-ARTICULAR.[ARTHROSCOPY]

43. ACL Tear- No repair Only Recontruction Graft - Autograft - common Allograft

44. Graft Options Autograft BPTB - Bone-Patellar Tendon Graft Hamstring Quadriceps Allograft

45. Bone-Patellar Tendon Graft Considered GOLD standard CLANCY, MODIFIED

46. Bone-Patellar Tendon Graft:STEPS A rear-entry commercial drill guide system ( Acufex , Smith & Nephew, Memphis, TN) is used for the femoral tunnel, and the bone plugs of the bone-tendon-bone composite free patellar tendon graft are secured in the tunnels with interference screws. Any intraarticular pathological condition is corrected with chondroplasty, meniscal repair, or partial meniscectomy, and the contents of the intercondylar notch are examined.

47. Harvest of the graft and the reconstruction can be done through two incisions or a single incision. The necessity of posteromedial or posterolateral incisions (as for meniscal repair), previous incisional scars, or surgical preference influences the choice of incision placement. The single skin incision begins 8 cm superolateral to the patella and courses distally to cross the tibial tuberosity to the anteromedial tibia

48. Expose the patella and patellar tendon through the plane of the prepatellar bursa. Measure the width of the patellar tendon. Make two parallel incisions through the full thickness of the tendon, 10 mm apart, from the inferior pole of the patella to the attachment of the tibial tuberosity if the patellar tendon is at least 30 mm wide. If the patellar tendon is not this wide, use only the central third.

49. Continue the parallel incisions through the aponeurosis, over the anterior surface of the patella from its inferior pole to the quadriceps tendon insertion, and distally through the periosteum over the tibial tuberosity, extending 2 to 3 cm inferior to the tendon insertion. The incisions mark the line for releasing the graft with its patellar and tibial tuberosity bony attachments

50. Take the central slip of 10 mm

51. BPTB Graft Advantages- Ease of harvest Consistent size & shape Strong bone-tendon interface Strong Bone to Bone fixaton Good healing

52. BPTB Dis-advantages - Risk of patellar # Patellar tendonitis Patello -femoral pain Donor site tenderness on kneeling Bigger incision scar Loss of sensation lat.to scar

53. Quadrupled Semi-T / Doubled STG graft 4 strands of Hamstrings = 250% strength of native ACL Advantages ‒ Stronger graft Smaller Incision- Cosmesis Can be used in skeletally immature Hamstring Grafts

54. GRAFT HARVEST

55. Hamstring disadvantage Soft tissue to bone healing Tunnel widening Technically difficult than BPTB Loss of Hamstring strength( apprx 10%)

56. Quadriceps Tendon Graft Bony end on one side and soft tissue strip on other Cross-sectional area thicker than BPTB Disadvantages- Donor site risks

57. Quadriceps tendon graft

58. Tendon exposure

59. Quadriceps tendon Advantage Comparatively less harvest site morbidity Larger cross sectional area of graft Disadvantage Bone block at only one end of graft

60. Allografts Advantages- No graft site mobidity Available off the shelf Boon- Multiligamentous Injuries Disadvantages- Risk of disease transmission Weak graft Delayed incorporation Not universally available,Expensive

61. SINGLE MOST COMMON CAUSE INCORRECT TUNNEL PLACEMENT

62. TUNNELS FOR ACL LENGTH DI A M ETE R POSITION

63. TIBIAL TUNNEL ENTRY POINT Tibial jig- set at an angle of 45-55 0 , 30 medial to mid sagittal axis Approx.. 4 cms below joint line

64. LANDMARKS - ACL Footprint Center of ACL footprint LATERAL Meniscus Post. Border of Ant. Horn Anatomic Tibial Tunnel

65. FEMORAL TUNNEL Access for tunnel placement -Through the Tibial Tunnel - Through medial instrument portal ANATOMICAL POSITION Over the top position Right Knee-9 ‒ 10pm Left Knee- 2 - 3 am

66. Anatomic tibial tunnel

67. Graft Fixation

68. GRAFT FIXATION Secure graft fixation is paramount to a successful reconstruction ACL rehab emphasizes on immediate movement and weight bearing High demand on initial graft fixation Ultimate long term success of an ACL reconstruction depends on healing of the graft fixation sites and biological healing

69. Ideal fixation Strong enough to avoid failure Stiff enough to restore knee stabilty Secure enough to avoid slippage

70. Ideal Graft fixation Anatomic Biocompatible Safe and reproducible MRI compatible Allow easy revision

71. Graft Fixation

72. ACL Graft fixation Major factor influencing graft’s mechanical properties in the immediate post-operative period Fixation site is the weakest link in ACL graft construct

73. Graft Healing BPTB – bone to bone healing by 6 weeks Soft tissue grafts – incorporate by sharpey fibres by 12 weeks Allografts take longer time Till then, FIXATION DEVICES need to play a major role

74. Anatomic Biocompatible Safe & reproducible MRI compatible Allows easy revision Ideal Graft Fixation

75. Anatomical – Directly at joint line, site of insertion of native acl Semi Anatomical – Transfixation devices, Distal interference fixation Non Anatomical – Buttons, Staples

76. Methods of fixation Bone to bone fixation -ingrowth of bone block within bone tunnel Fixed with interference screws or press fit bone plugs Tendon to bone fixation Tendon tissue heal to bone to achieve bony integration

77. Based on Different mechanisms Femoral fixation: Hardware-free method Hybrid technique Tibial fixation

78. Fixation concepts Direct extra-articular fixation Graft anchored outside the joint directly to the bone Indirect extra-articular fixation Graft anchored outside the joint using single or loped threads Reduces effective graft length

79. Fixation concepts Direct peri-articular fixation Graft pressed against wall of bone tunnel Fixation at level of joint line Graft fixed directly at the level of joint space

80. Soft Tissue fixation – interference compression Compressive loads transversely to the longitudinal axis of the graft Load shared along 3 interfaces Bone-screw Screw-tendon Tendon-bone

81. Expansion One or more cross pins pass through Graft & femoral tunnel As pins inserted transversely into the tunnel -> increase volume of graft -> pressure against tunnel walls (pressure in centrifugal way with respect to pin insertion points) Fixation based on initial press fit of graft into tunnel Rigid-Fix

82. Suspension - cortical Metal plates with suture loops Hardware over lateral cortex of distal femur suspends graft into the femoral tunnel Resistance vectors are parallel & opposite to the pullout forces

83. Suspension - cancellous Graft suspended to screw/press fit anchor which is fixed to cancellous bone of femoral metaphysis Resistance is due to transverse compressive forces at cancellous bone-hardware interface Linx -HT ( Depuy Mitek )

84. Suspension – cortico-cancellous Transepicondylar fixation system based on transverse suspension bar that is perpendicular to pull out forces Bio-Transfix ( Arthrex )

85. Soft tissue fixation – tibial fixation compression devices Compressive loads transversely to the longitudinal axis of the graft Load shared along 3 interfaces Bone-screw Screw-tendon Tendon-bone

86. Expansion devices Expandable four-channel, ridged sheath & tapered expansion screw Four channels grip 4 strands of graft into separate compartments & compress graft strands against cancellous bone in order to maximize bony integration GraftBolt ( Arthrex ) Expandable ridged sheath Tapered expansion screw

87. Cortical anchoring devices Staples Sutures over post Screws Spiked washers

88. Interference compression Transverse compression Transverse suspension Hybrid system Press Fit Fixation concepts: Bone to bone fixation

89. Interference compression Generation of friction between bone block & bone tunnel wall Engagement of screw threads into bone block & bone tunnel wall

90. Transverse compression Blunt nosed transverse screw enters femoral tunnel from lateral cortex Pushes bone plug against medial tunnel wall

91. Transverse suspension One or more cross pins that pass transversely through the bone plug

92. Press fit fixation Autologous bone plug/ Beta tricalcium phosphate plug No fixation device

93. Fixation devices

94. Interference screw Interference is defined as the amount by which the diameter of the screw exceeds the gap between the graft & the tunnel Interference screw for BPTB – Gold Standard Minimizes graft tunnel motion Less femoral canal widening

95. Screw divergence Difference between angle of tunnel & screw direction More with transtibial technique >20 deg compromises stability

96. Metallic screws Traditional fixation for many years High initial fixation strength Damage to bone-tendon junction Violation of posterior cortex Intra articular hardware Hardware removal during revision Distortion of MRI images

97. Bio screws Biodegradable Polyglycolic acid (PGA), poly-p-dioxanone and copolymers of polyglycolic acid/polylactic acid (PGA/PLA), poly-l-lactic acid (PLLA) & poly-d-lactic acid (PDLA) Degrade slowly Biocomposite Combination of polymers & osteoconductive materials [Beta-tricalcium phosphate ( β- TCP) or hydroxyapatite] Ultrastructural properties for cell adhesion Degrade more quickly, osteoconductive properties promote faster graft incorporation & bone formation Polyglycolide absorbs early, hence fixation can become lose early Crystalline polylactides take years to get absorbed

98. Advantages disadvantages May break during insertion Need special screw driver Tissue reaction can occur Fixation lost after partial degradation By 6 weeks, 80% loss of strength, 60% loss of stiffness Tunnel widening more No need for implant removal Revision easier Does not interfere with MRI

99. Endo button Fixed Loop suspensory fixation Insertion & Connection parts Insertion part drilled to the diameter of the graft Connection part is 4.5mm diameter No wear/abrasion of the graft Adv Can be used in osteoporotic bones and femoral tunnel blow out Disadv Fixation away from aperture – tunnel widening & Bungee effect

100. Tight rope Adjustable Loop suspensory fixation Loop length reduced after flipping by tightening the rope Allows full length filling of the graft part in the tunnel

101. Fixation devices Fixation site is the weakest link in ACL graft construct Clinical results of various methods are comparable Interference screw gold standard for Bone grafts Suspensory fixation for femur & compression fixation for tibia commonly done for Soft tissue grafts

102. Sources Campbells 12 th edition Millers 7 th edition Rockwood

103. Thank you