The Evolution of ACL Deficient Classification

1. The Evolution of ACL Deficient Classification ACL Journal Club April 17, 2009 Andrew Lynch, PT Department of Physical Therapy

2. Clinical Differentiation of ACLD Patients • Who are those people who can return to jumping, pivoting and cutting sports without surgery? • How do we identify them in the clinic? • What measures will allow us to confidently tell a patient that they may be able to return to sports? • Conversely, who absolutely needs surgery?

3. Eastlack ME, Axe MJ and Snyder-Mackler L Laxity, Instability and Functional Outcome after ACL Injury: Copers versus Noncopers MSSE 31 (2):210-215 Eastlack et al, MSSE, 1999

4. What defines a Coper? • ACL Deficient (ACLD) who “coped with their injuries without ligament surgery.” (Daniel) • Not highly active • This is has since been termed an Adapter • Avoid instability by decreasing activity levels Eastlack et al, MSSE, 1999

5. What defines a Coper? • They are not a non-coper: • Those unable to complete activity at the same level as before their injury without repeated episodes of giving way • The sensation of giving way has been reported as similar to a pivot-shift test for anterior lateral rotary instability (McDaniel and Dameron, 1980) • Also associated with pain, swelling and knee buckling Eastlack et al, MSSE, 1999

6. What defines a Coper? • Snyder-Mackler et al, JBJS 1997 • Copers are those who returned to full sports participation without surgery • Function is not linked to laxity • This was the operational definition of a coper used by Eastlack et al. Eastlack et al, MSSE, 1999

7. Outcome measures: Joint laxity (KT-2000) Lysholm Scale Knee Outcome Survey Activities of Daily Living (ADL) Sports Global Rating Score Strength Testing (Burst) Hop Series (Noyes, AJSM 1991) Subjective Questionnaires: Time from injury Chronic: >6mos Sub-acute: 1-5mos Brace usage Episodes of Giving Way 0, 1, 2, 3, >3 Extension of Previous Injury What Clinical Measures May Help Delineate? Eastlack et al, MSSE, 1999

8. Clinical Characteristics of Copers • Highest amount of laxity – 5.5 mm (no significant difference) • Scored higher on functional outcome measures • KOS-ADLS and SAS • Lysholm • Global Rating • Quadriceps Index • All 4 Hop Scores • 25% of copers reported more than 3 episodes of giving way • 73% of chronic ACLD patients Eastlack et al, MSSE, 1999

9. Multiple Regression Analysis • Global Rating Score • KOS-SAS • Quadriceps Index • Cross-over Hop • R2 = 0.66 • Specificity = 92% • Sensitivity = 97% Eastlack et al, MSSE, 1999

10. Fitzgerald GK, Axe MJ and Snyder-Mackler L A decision making scheme for returning patients to high-level activity with non-operative treatment after ACL rupture. KSSTA (2000) 8:76-82

11. Purpose • Propose classification system for acute ACLD patients to determine who may be capable of returning to sport without surgery (in the short term). • Present results from a preliminary study of these rehabilitation candidates (potential copers) and their attempts at non-operative management.

12. Subjects • 93 patients were classified and included • Exclusions included: • Multi-ligament injured knee • Fracture/dislocation • Bilateral involvement • MRI findings

13. Screening Exam • Functional Hop Series (Noyes) • Quadriceps Burst Superimposition Testing • Global Rating of Knee Function • KOS-ADLS • Frequency of giving way

14. Surgical Candidates Multiple episodes of giving way Unstable during ADLs Rehabilitation Candidates No indicators of instability Multiple Regression: r2 = 0.72 Global Rating Give-ways KOS-ADLS Timed-hop test Cutoffs established 2SD below mean for rehab candidates Development

15. Non-operative Management • Aggressive rehabilitation to prepare subject for sport • Success: return to pre-injury activity without giving way • 28 PC attempted non-op, 22 succeeded (79%) • 9 with subsequent ACLR • 1 with contralateral injury • 12 chose to forego ACLR

16. Discussion • 58% of ACLD proceeded with surgery without attempting non-op rehab • 54 classified as non-copers • 11 classified as PC, opted for surgery • 79% of rehab candidates were successful in their return to sports • Significantly higher than in any other reported cohort • Those who failed had a significantly lower timed hop performance

17. Biomechanical Differentiation • With a screening system in place, rehabilitation candidates can be identified. But what makes them better candidates? • Muscular control? • Specific movement patterns? • If these patterns can be identified, then they could be taught to patients through rehabilitation, thus, decreasing the need for surgery.

18. Rudolph KS, Eastlack ME, Axe MJ, Snyder-Mackler L 1998 Basmajian Student Award Paper: Movement Patterns After Anterior Cruciate Ligament Injury: a Comparison of Patients Who Compensate Well for the Injury and Those Who Require Operative Stabilization Journal of Electromyography and Kinesiology 8 (1998):349-362 Rudolph et al, J EMG and Kines, 1998.

19. Eight (8) Non-copers Instability during activities of daily living Planned surgical reconstruction Eight (8) Copers Returned to pre-injury activity without limitation Global Rating of 85% <1 give way since injury Subjects Rudolph et al, J EMG and Kines, 1998.

20. Clinical Measures: Arthrometry (KT2000) Burst Superimposition Testing Quadriceps Index Global Rating Laboratory Measures: Motion Analysis 5 VICON cameras (120 Hz) Kinetic Data Bertec FP (480 Hz) 3 Activities Free Speed Walking Free Speed Jogging 10-inch Step Over Methods Rudolph et al, J EMG and Kines, 1998.

21. Clinical Results • Laxity • 6.7mm in Non-copers • 6.4mm in Copers • Quadriceps Strength • Statistical trend (p=0.088) toward greater strength in copers • Global Rating • Copers (92%) significantly better than non-copers (54%) • Quadriceps Index showed correlation to global rating in both groups Rudolph et al, J EMG and Kines, 1998.

22. Copers No kinematic difference between knees Involved Kinetic Changes: ↓peak vertical GRF ↓ knee extensor moment ↓ knee extensor power absorption Non-copers Initial Contact and Loading Response Less knee flexion Involved Kinetic Changes: ↓peak vertical GRF ↓ knee extensor moment ↓ knee extensor power absorption Walking No differences between groups at mid- and terminal-stance. Rudolph et al, J EMG and Kines, 1998.

24. Copers: No kinematic differences Decreased involved vertical GRF Non-copers: Decreased knee flexion at initial contact through loading response to peak knee flexion Decreased involved vertical GRF more than copers Jogging Rudolph et al, J EMG and Kines, 1998.

26. Copers Similar flexion bilaterally to ascend Increased involved extension during support Non-copers Decreased knee flexion to ascend stair with involved Increased involved extension during support Peak vertical GRF decreased on both limbs Step Task Rudolph et al, J EMG and Kines, 1998.

27. Ubiquitous decrease in knee extensor moments and vGRF Increase in plantarflexor power absorption Non-copers: Decreased KF Decreased vGRF Copers: Decreased power absorption Similar kinematics Non-copers may exhibit increased co-contraction Causing articular compression Non-copers exhibit increased frequency of giving way Causing articular shear Quadriceps strength is not the primary stabilizer of the knee Conclusions Rudolph et al, J EMG and Kines, 1998.

28. Conclusions • Non-copers use a stiff knee strategy • Stability at the sacrifice of mobility • Increased instability • Copers move with more symmetry • Precise, selective movement patterns as opposed to gross co-contraction • allowing them to manage without an intact ACL Rudolph et al, J EMG and Kines, 1998.

29. Chmielewski TL, Rudolph KS, Fitzgerald GK, Axe MJ and Snyder-Mackler L Biomechanical evidence supporting a differential response to acute ACL injury Clinical Biomechanics 16 (2001) 586-591 Chmielewski et al, Clin Bio, 2001.

30. Purpose • Investigate the movement patterns of potential copers as identified by the screening process. • Non-copers, copers and healthy subjects already studied.

31. Methods • Similar to Rudolph • Walking • Jogging • Variables of Interest: • Peak knee flexion angle (both) • Knee extensor moment at PKF (both) • Knee flexion at initial contact (jog) • Vertical GRF at PKF (walk) • Peak vertical GRF (jog) • Total support moment at PKF (and components)

32. Comparisons with Healthy • Walking at peak knee flexion • Knee flexion angle • Decreased compared to control and contralateral • Knee extensor moment • No difference • Vertical GRF • Decreased compared to control • Components of Total Support Moment • Decreased control at the knee • Increased control at the ankle

33. Comparisons with Healthy • Jogging • Knee flexion at initial contact • Decreased • Knee flexion at PKF • Decreased • Knee Extensor Moment • No difference • Peak vertical GRF • No difference

34. Conclusions • Potential copers resemble uninjured subjects kinetically • Potential copers resemble non-copers kinematically • Stiff knee strategy • Support moment alterations are similar to copers • Move support to ankle • Non-copers shift to the hip

35. Clinical Themes • Laxity does not predict instability or function • Functional hop scores are able to distinguish between copers, non-copers and potential copers • May also be predictive of those who will give-way with return to sport • Self-report scores are discriminant between those with good knee stability and those without • No one measure can predict dynamic knee stability, therefore a cluster must be used. • Selective determination of those who can attempt non-operative management improves outcomes.

36. Biomechanical Themes • Non-copers use a stiffening strategy and decrease moments to prevent further episodes of instability in walking and jogging • May be due to quadriceps weakness • Copers move symmetrically, without gross co-contraction to maintain stability. • Potential copers display an intermediate strategy. • Imperfect precision to move like a true coper. • Still demonstrate knee stiffening, similar to non-copers.