1. A Comprehensive
Rehabilitation Protocol for
Physical Therapists on
Return to Skiing after
Surgical ACL repair
Dana Hindman
Boston University Sargent College
Mentor: Jonathan Raymond, PT

2. Lecture Objectives
• Review ACL anatomy and biomechanics
• Educate about common ski injuries, epidemiology
and risk factors for ACL disruption
• Understand skiing mechanics and musculoskeletal
requirements for proper ski form
• Discuss surgical intervention techniques for skiers
with ACL disruption
• Propose a safe and effective rehabilitation program
for skiers returning to sport after an ACL surgical
repair
• Review appropriate outcome measures for use
during the functional stage of rehabilitation
• Compare bracing techniques and their effectiveness
during return to skiing

3. ACL anatomy
O: Posteromedial aspect of lateral
femoral condyle of femur
I: anterolateral aspect of medial
tibial spine
• Consists of 2 fiber groups that
originate from separate
“bundles”
– Not as well-defined as
previously hypothesized1
• Primarily consists of type I
collagen fibers to resist tensile
forces1
• Multiple non-parallel fibers
– allow for dissipation of forces
and adjustment of length in
response to multi-directional
loads2

4. A biomechanical review of the ACL
• Works synergistically with other
structures to maintain equal
balance of forces at the
tibiofemoral joint2
• Primary restraint against anterior
tibial translation3
– Provides >80% of between 30-90°
of knee flexion
– Intact ACL allows for ATT 3-5mm
• Major constraint against
tibiofemoral rotational
movements and external valgus
forces2
• ACL loading during activity3
– 169 N during walking
– 445 N during stair descent
– Skiing?!

5. Epidemiology of ski injuries
• Prior to 1980’s, tibia and ankle fractures were the most
common ski injuries4
– Advancements of bindings/boot systems improved these by
~90%
• Knee injuries account for 33.4% of all injuries sustained
during alpine skiing3
• 45-60% of all ski-related knee injuries involve the ACL
– Combined MCL and ACL more common than ACL alone2
• 10% of all ski accidents involve the ACL4
– 2x higher incidence since 1970
In highly competitive skiers:4
• Primary ACL injury rate equal between men and women
– higher recurrent ACL injury rate among women (41.5%)
• Prevalence of bilateral ACL rupture as high as 34%

6. Risk Factors: Non-modifiable
• Previous knee injury
– 3.1x higher risk for ACL-reconstructed
knees than ACL-intact knees5
• Female during the pre-ovulatory
phase of menstrual cycle
– 2.4-fold increase in ACL ruptures
during the follicular and ovulatory
phases of menstruation6
• 3-fold elevation in relaxin
• Poor skiing conditions7,8
– End of the day
– Extreme weather (wind, snow, ice,
limited visibility)
– Hazardous terrain
• Moguls
• Glades
• Powder

7. Risk factors: Modifiable7
• Core deficits
– Absolute and relative flex: ext strength ratio > or < 1
– Decreased neuromuscular control of the trunk
– Poor hip abductor and extensor strength
• Hamstring: Quadriceps strength ratio deficits
• Side to side differences in strength,
neuromuscular control, and proprioception
• Poor balance ability

8. Mechanisms of ACL injury
• Phantom foot
– 70% of all ACL injuries during
skiing3
– Occurs when skier catches
an edge during a turn or jump
landing
– Components:8
• Trunk COM shifted posteriorly
• Hips below knees
• Uphill ski un-weighted
• Upper body facing downhill ski
– Results in extreme knee flexion
and tibial IR of downhill ski

9. Phantom foot

10. Mechanisms of ACL injury
• Boot-induced anterior drawer (BIAD)3
– Mainly occurs during a jump landing
– Quick quadriceps contraction with an extended
knee when tails catch the snow
– Forces the back of the ski boot against the calf

11. Mechanisms of ACL Injury
• Slip-catch9

12. Mechanisms of ACL injury
• The dynamic snowplow9

13. Downhill skiing biomechanics
• “Skier’s tuck” position
– Aerodynamic
– Components:
• Shoulders lower than mid-back
• Rounded spine
• Full hip flexion
• Knee flexion 86-114°9
• Elbows bent to 90°
• Hands in front of face (above
knees)
• Posteriorly directed COM
during jump landings was
shown to have the highest
correlation to ACL
disruption12
– T-F joint compression and
ATT due to extreme
quadriceps contraction

14. Downhill skiing biomechanics
Slalom turning
Outside leg: accepts majority of the weight bearing
forces
Inside leg: achieves greater hip and knee angles;
greater torque forces at the knee joint

15. Surgical considerations for the ACL-
injured skier
• Surgeon-dependent decision
– Allograft vs. autograft
– Reconstruction site for autograft
• Most common autograft sites: bone-patellar tendon-bone and
hamstring soft tissue graft
• No differences between bone-patellar-bone and hamstring
graft10
– Laxity
– Clinical outcome
– Time to return to sport
– Function (single hop test)
• New technique being investigated using quadriceps tendon11
– Easy to harvest
– reduces donor site morbidity
– Decreased A-P laxity in knee joint compared to BPTB @ 24 months
– Success rate of graft similar to HS and BPTB techniques

16. Proposed Post-ACLr
Rehabilitation Protocol for Skiers
Goals for all stages:
• protect the graft
• prevent further ACL injury

17. Phase 1: Acute early rehabilitation
Weeks 1-3

18. Phase 1: GOALS
1. Decrease pain/knee joint effusion
2. Increase knee joint mobility
3. Prevent incisional/scar tissue adhesions
4. Normalize gait pattern
5. Prevent deconditioning

19. Phase 1: PROGRAM
• Cardiovascular conditioning
• Soft tissue mobilization/scar tissue
massage
• Joint mobilizations PRN
• Isometric quadriceps recruitment
– Via NMES
– EMG-based biofeedback
• Core strengthening exercises7
• Non-injured leg strengthening work

20. Minimum criteria for advancement from
phase 1phase 212
1. Minimal joint effusion
2. Normal symmetrical gait pattern
3. Symmetrical functional quadriceps AND
HAMSTRINGS recruitment
4. No episodes of giving way/apprehension with
closed-kinetic-chain activities or ADLs
5. Knee PROM: symmetrical and functional
extension; 90% of flexion of contralateral knee

21. Phase 2: Advanced phase
Week 4-10

22. Phase 2: GOALS
1. Normalize lower extremity biomechanics
2. Restore muscular strength
3. Improve CV endurance
4. Optimize neuromuscular control, balance,
proprioception

23. Phase 2: PROGRAM
• General LE stretching program PRN
• Cardiovascular exercises
– Treadmill w/ incline
– Eccentric LE ergometry13,14
• no increased knee pain, effusion or stability
differences between traditional and ECC groups
• Greater improvements in quad strength and
hopping distance in ECC group
– Elliptical trainer
• LE weight shifting
• Closed-kinetic-chain knee flexion
exercises12
– No >than 60° of TF flexion initially d/t ATT @
higher angles
– TRAIN FOR ENDURANCE
• Targeted hip and abdominal strengthening
exercises (clams, bridging, bird-dog, etc…)

24. Skier tuck position on 2 half
foam rollers
BOSU w/ lateral sport
cord resistance
Hip and knee neuromuscular exercises in
ski-specific positions

25. Minimum Criteria for Advancement from
Phase 2Phase 312
1. Symmetrical double-limb squat held at 60°
for 30s
2. Symmetrical single-limb squat to 30° without
varus/valgus compensations
3. Full strength (5/5) of hip abductors,
extensors and internal rotators in standard
MMT positions

26. Phase 3: Sport-specific training
Months 2-4

27. Phase 3: GOALS12
1. Achieve quadriceps and hamstring strength
values ≥85% of uninvolved leg
2. Improve neuromuscular stabilization at the knee
joint
3. Improve CV fitness to pre-injury levels
4. Successfully complete a functional return-to-
skiing test

28. Standardized outcome measures for
ACL rehabilitation
• Combination of 4 hop tests more valid and
reliable than a single test alone15
– Highly correlated to changes on GROC and LEFS

29. Vail Sport Test16
• Specific functional outcome measure for return-to-skiing
• Assesses a series of dynamic, multi-planar functional
activities against sport cord resistance
• Measures a patient’s power, neuromuscular control,
movement quality and muscular endurance
• Scoring based on judgment of clinician on form, time and
pain levels
• Total composite score of 54 points
– Higher=better
– Passing score is 46/54 (85%)
• Excellent psychometric properties
– Intra-rater reliability 0.95-1
– Inter-rater reliability 0.97 (average of all components)

30. Vail Sport Test: Backward Jog

31. Phase 3: PROGRAM
• CV training with high resistance
• Targeted hamstring and quadriceps strengthening
exercises for strength and power
– Eccentric hamstring curls with ankle weights/pulley
system
– Sports cord WB exercises
• Double-limbsingle-limb plyometric ski-specific
lower extremity exercises
– Slow eccentric phase w/ normal speed concentric phase
– Shuttle leg pressfull WB plyometrics progression
• Lateral agility training

32. Advanced sport-cord exercises
Single leg squat
against sports cord
resistance
Lateral bounding
movement with sports
cord perturbations in
multiple directions
Forward and backward
running movements
against sports cord
tension

33. Opposing the phantom foot

34. Lateral agility training options for skiers
• Lateral box jumps (double limbsingle limb)
• Lateral box jumpovers
• Pro-fitter 3D machineTM
• PRO ski simulatorTM
Pro-Fitter
Ski simulator

35. Minimum Criteria for Advancement
from Phase 3Phase 412
1) Examination and clearance by referring physician
2) Successful completion of the Vail Sport Test or
other series of functional tests determined by
trainer/PT
3) Communication with trainer/ski instructor and
physician on recommendations for on-slope
rehabilitation

36. Phase 4: Return-to-sport training
Months 4-6

37. Stage 4: Return to ski program12

38. To brace or not to brace:
That is the controversy!
The jury is not out…
• Prospective cohort study (2006)17
demonstrated that using a CTi2 brace
during skiing after ACLr demonstrated:
– Decreased laxity of the surgical graft
– Statistically significant lower injury rate
(4%) compared to the the non-braced
group (9%)
– All knee injuries requiring surgery @ 6
months were in the non-braced group
CTi2 brace

39. To brace or not to brace:
That is the controversy!
BUT…
• A 2014 study trialed 4
different braces on ACL-
injured patients18
B1-soft knee sleeve w/ patellar
reinforcement + 2 lateral
stabilization metal bars
B2-neoprene sleeve w/ metal
lateral stabilizers
B3-elastic brace w/ double-
joint metallic bars, patellar
reinforcement + fixation straps
B4-rigid knee brace w/ all B3
components
B1
B2
B3
B4

40. To brace or not to brace:
That is the controversy!
• Results showed:18
– B2 improved stability index in A-P direction compared to
other brace options
– B3 worsened stability index in A-P direction than without
any knee support
– No significant difference for braced group in medio-lateral
stability or sensorimotor function compared to non-braced
group
SO WHAT DO WE DO??
• Educate the patient about the bracing research despite its
conflicting evidence
• Recommend that the patient discuss with their
surgeon/orthopedist whether or not bracing is right for
them

41. Equipment considerations for the ACL
injured skier
• Current bindings have pivot point at the center of
the heel radius
• Best setup based on biomechanical analysis20
– 2 binding release mechanisms anteriorly and
posteriorly
– fast release characteristic
• KneeBinding unitTM
– Pure lateral heel release mechanism
– Flat binding with width of the boot
– Provides some flex for shock absorption during jump
landings and extreme carving

42. Other components of patient education21
• Common mechanisms of injury
• Appropriate fall technique
– “if you feel like you are going to fall, fall”
– When in doubt, shift your mass forward
• How to reduce individual risk based on modifiable and non-
modifiable factors
– Avoid skiing in poor weather and slope conditions as possible
– Do not ski beyond fatigue
– Get ski tune-up and binding setting checks often (at least 1x/yr)
– Do routine testing of binding release every single time you hit
the slope
– Ski under control—if you’re skiing too fast for YOUR level, SLOW
DOWN!
• Resources for equipment and further on-slope training

43. Limitations of research
• Majority of the body of literature on skiing and
injuries is from before 2000
• Only 6 studies that address rehabilitation specific
to returning to skiing
• Insurance limitations on length of rehabilitation
course for these patients
• Equipment needed for return-to-skiing
rehabilitation expensive and not readily available
for use in most outpatient, non-specialized clinics

44. Questions?
Feel free to email me at
dhindman@bu.edu with any follow
up questions/concerns regarding this
topic. Happy to find you the answer if
I don’t have it immediately!

45. Thank You!
(and thanks Jon, you’re the best
mentor EVER!)
Eat all the brownies…PLEASE!

46. References
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47. References Continued
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