TKR INSTABILITY OF THE – DIAGNOSIS/CAUSES/TREATME NT

Jose A Rodriguez, MD Center for Preservation and Reconstruction Lenox Hill Hospital NYC  Most successful surgery with best long term survivorship

 Up to 20% of patients are not satisfied with the outcome following total knee replacement – Predicting dissatisfaction following total knee replacement: a prospective study of 1217 patients. Scott CE et al JBJS Br 2010 Early Revision

 TKR 3% revised in first 24 months  Heck DA, Melfi CA, Mamlin LA, Katz BP, Arthur DS, Dittus RS: Revision rates after knee replacement in the United States. Med Care 1998;36:661-669.

 Up to 22% of Revision TKR for instability  Sharkey PF, Hozack WJ, Rothman RH, Shastri S, Jacoby SM: Why are total knee arthroplasties failing today? Clin Orthop Relat Res 2002;404:7- 13 Laxity ≠ Instability

 Some patients can tolerate a wide variety of laxity states with no symptoms

Instability

 Functional related to Laxity, Ligament imbalance or incompetence Tension - Balance

 Stiffness ------Instability

/---Good Function---/

 Judgment  Black / White

 Grey Judgement – soft tissue tension

Differing requirements

 70 yo Woman, 140 lb, Anxiety, pre-op 90 deg

 55 yo Man, 240 lb, Tennis Pro, 130 deg Instability

 Related to Composition of Gaps

 Goal Rectangular -- Symmetrical

Balanced Flexion gap = Extension Gap Gap imbalance

 Flexion loose / tight

 Extension Loose tight

 Asymmetric gaps / rotation Gaps

 Trapezoidal --- Asymmetrical

Related to Bony cut alignment Soft tissue Contracture Soft Tissue Stretching Gaps – filled by implants

 Femoral and Tibial contributions

 Alignment – sagital

 Rotation – Coronal

 Implant (poly) thickness Symmetrical Extension Instability

 Extension gap rectangular >> Flexion gap  Imbalance  Hyperextension

 Over resection of distal femur Symmetrical Extension Instability

 Management  Distal femoral augment to lower joint line

 Larger polyethylene - create flexion tightness Asymmetrical Extension Instability

 Trapezoidal Ext gap

 Sagital Alignment  Soft Tissue Contracture  Soft tissue Stretching  Excessive release  MCL incompetence

Flexion Instability

 Excessive laxity of flexion gap  Aberrant movement  PCL Insufficiency – posterior tibial translation Diagnosis Pagnano MW, Hanssen AD, Lewallen DG, Stuart MJ: Flexion instability after primary posterior cruciate retaining total knee arthroplasty. Clin Orthop Relat Res 1998;356:39- 46

 25 PCL Retaining TKR – Revised

 Instability without giving way  Swelling, /effusion  Diffuse Tenderness  Posterior sag / drawer @ 90 degrees  10 pts Revised 95 – 02

 Sense of Instability without giving way 8/10  Difficulty with stairs 7/10  Recurring effusion 7/10  Anterior knee or diffuse soft tissue pain 7/10  Tenderness: Pes Anserinus, peripatellar, Hamstring insertions

 Tibial Posterior Slope Avg 7 degrees ( 3 – 11) Physical Exam

 Post Sag

 Tenderness

 Ant Drawer

 Sulcus sign

 Rotational Laxity Ant Drawer Sulcus sign Loss of Posterior Femoral Offset Causes-

 Anteriorizing the femoral component to avoid notching

 poor restoration of post condylar offset Causes-

 Excessive tibial slope- as most PS designs are built in with no / minimal tibial slope Causes-

 Asymmentric flexion space – femoral component internal rotation with/without tibial varus Isolated Flexion Instability In Posterior Stabilized Total Knee Replacements Deshmane P, Deshmukh A, Scuderi G, Rodriguez J

 18 05 – 10 Revised for Instability

 Well fixed, reasonably aligned  > 5 mm anterior Translation  3 – 5 mm Condylar Lift-off with rotation  Sulcus sign Isolated Flexion Instability In Posterior Stabilized Total Knee Replacements Deshmane P, Deshmukh A, Scuderi G, Rodriguez J

 16/18 Recurrent Effusions  18/18 Difficulty with Stair Descent  18/18 Sense of knee feeling loose or unstable  9/ 18 Interface Lucency / Erosion Treatment  Understand criteria for evaluation of stability  Well aligned / rotated bony cuts  Soft tissue tension balance in extension  Flexion Extension Gap Balancing Operative Options

 Tibia 90 deg – Proper rotation  Femur – posteriorize – augment / metaph sleeve  Femur – joint line raise lower  Femur – rotation, lat augment

 Poly exchange Surgical Management Flexion Instab  Create Stable Tibial base, well aligned, no slope

 Assess Gaps

 Posteriorize Femur – posterior augments  Offset stem vs short cemented stem  Assure proper rotation Fehring TK, Odum S, Griffin WL, Mason JB: Outcome comparison of partial and full component revision TKA. Clin Orthop Relat Res 2005; 44

 Full component revision was more successful than partial revision, especially for a diagnosis of instability (P = 0.0001).0:131-134 Mayo Series combined

 9 / 10 knees successfully stabilized  19/22

 Femoral and tibial revision  Fill flexion space  70 Rev TKR for Instability  50 both Comp, 10 one Comp, 11 poly only

 Avg 39 mo  17 (24%) cont instability sx

 Both Comp rev, Fem Augments assoc with good outcome  Poly alone – poor outcome  27 Knees Instability Poly exchange  12 Failed avg 3 yrs  5 Instab  1 tib loose  1 stiff  1 inf

 15 survived avg KSS 80 Flexion stability assessment

 Reduction appearance  Anterior Drawer 2 – 5 mm  Rotation – Condylar lift off  Translation in traction – simulated sulcus sign Ant Drawer y Posterior Stabilized Total Knee Replacements Deshmane P, Deshmukh A, Scuderi G, Rodriguez  12 Femoral and Tibial Revision  Femoral augment posteriorly  No tibial slope  Gap Balance  Proper rotation

 6 Poly exchange – Constrained Case

 Varus, Neutral femoral rotation, Lig laxity Cumulative Error

 3 degrees of tibial varus

 Slight Fem Ext Rot – Condylar liftoff

 5 degrees Tibial slope

Condylar Liftoff

y Posterior Stabilized Total Knee Replacements Deshmane P, Deshmukh A, Scuderi G, Rodriguez  18 / 18 Instability symptoms improved

 KSS clinical 53.5 to 81.2 functional 50.5 to 79.1

Ant Drawer 2 – 5mm No Condylar liftoff Instability

 Complicated 3 dimensional problem  Understand component parts  Address each anatomic variable

 Many are preventable  Most are treatable Prevention

 Proper bony cuts – coronal alignment  Proper rotation  Gap balancing  Stability testing

Thank You

Poly xchange

 Criteria to evaluate stability

 Apply criteria to make decision

 Post capsular release will only get you so much extension

Engh22 reported on eight patients with flexion instability who were managed with placement of a thicker tibial insert. Only four knees were stabilized, and one knee was rerevised.

Engh GA. Tibiofemoral instability. In: Proceedings of the 67th Annual Meeting of the American Academy of Orthopaedic Surgeons; 2000 Mar 15-19; Orlando, FL. Rosemont, IL: American Academy of Orthopaedic Surgeons; 2000. p 32-4. Medial-Lateral Stability Post Total Knee Arthroplasty Affects Function: Results From A Joint Registry Seah et al, Singapore AAOS 2011  Incorrect placement of the femoral component too anteriorly and proximally, as well as compensating for that position with a thicker tibial insert, can cause medial-lateral instability only in midflexion.  Martin JW, Whiteside LA: The influence of joint line position on knee stability after condylar knee arthroplasty. Clin Orthop 1990;259:146– 156.  Causes of asymmetric extension instability include collateral ligament and inadequate collateral ligament release. Iatrogenic collateral ligament injury can occur by complete disruption during bone cuts, by vigorous knee exposure, or by ligament overrelease

 MCL Repair Leopold SS, McStay C, Klafeta K, Jacobs JJ, Berger RA, Rosenberg AG: Primary repair of intraoperative disruption of the medial collateral ligament during total knee arthroplasty. J Bone Joint Surg Am 2001;83:86-91 Assessment

 Collat Lig  Ext mech  Alignment  Foot / deformities Berend ME, Ritter MA, Meding JB, et al: Tibial component failure mechanisms in total knee arthroplasty. Clin Orthop Relat Res 2004;428:26- 34

 Valgus Tibial Cuts  Varus Tibial Cuts  Excessive tibial slope

 Associated with early failure  Vince KG, Abdeen A, Sugimori T: The unstable total knee arthroplasty: Causes and cures. J Arthroplasty 2006;21:44-49.

 Plano-valgus hindfoot – associated with instability with PCL sparing TKR