Ankle arthritis

1. Ankle arthritis

2. Introduction

3. Pathophysiology of ankle arthritis – why and how?
•Primary OA is a rare entity in the ankle
•Increasing incidence of secondary OA in the ankle
•Normal anatomy of the ankle determines its low primary wear characteristics

4. High congruency
Constrained by
ligaments
4mm joint space
on mortise view
Mortise widens
from posterior to
anterior
HIGH CONGRUENCE
HIGH STABILITY

5. Properties of the ankle joint
NORMAL PEAK CONTACT STRESSES IN THE ANKLE ARE HIGH
Why? – At 500N, surface contact area in:
Hip = 1100 mm2
Knee = 1120 mm2
Ankle = 350 mm2
ANKLE CARTILAGE IS THIN
Hip = 3-6 mm
Knee = 3-6 mm
Ankle = 1-2 mm

6. Properties of the ankle joint
TENSILE STRENGTH OF ANKLE CARTILAGE HIGHER THAN HIP AND KNEE
Better cross-linking
Studies show lack of neutrophil collagenase in ankle cartilage
Studies show lack of IL-1 receptors in ankle cartilage

7. Primary, non-traumatic OA
Rare - High congruency
High stability
Excellent tensile/metabolic properties
Secondary, post-traumatic OA
More common- >1mm incongruence = 40% increase in contact stress
Stiff cartilage less adaptable to incongruity

8. Long-term incongruence and instability increase local contact stresses beyond
the capacity of the joint to repair itself

9. Prevalence of OA
Most studies are cadaveric and x-ray
Poor correlation between x-ray changes and clinical symptoms
X-rays often do not show full thickness OA
Cadaveric study (Muehlman et al.):
50 subjects, mean age 76
Grade 3/4 OA in 18% ankles
Grade 3/4 OA in 66% knees
Studies suggest surgical procedures for advanced OA ankle far less
Common than for OA knee/hip
Why....? - Less pain and functional restriction in OA ankle.....?
- Lack of understanding of OA ankle and its treatment....?
..........................Or more primary hip and knee surgeons...?

10. Clinical features
Patient factors
•History of trauma/recurrent ankle sprains
•Inflammatory arthritis
•Haemophilia, gout, AVN, infection
•Diabetics with co-morbidity – prone to Charcot
Pattern of pain
•Uphill walking pain – anterior ankle impingement
•Downhill walking pain –posterior ankle OA
•Uneven ground pain – subtalar OA
•Sub-fibular pain – ankle or subtalar joint, calcaneal impingement on
fibula or peroneii

11. Examination
•Gait Back-knee gait with fixed equinus – anterior osteophytes
•Alignment
•Examine neurovascular status
•Skin - Beware of vasculitis in the rheumatoid patient
•Points of maximal tenderness
•Range of movement
•Ligament stability
•Evidence of tendonopathy

12. Imaging – X-ray
AP, Mortise, Lateral views
Stress views out -dated
Joint space narrowing, sclerosis, cysts
osteophytes

13. Imaging – CT
•Excellent for ankle arthritis
•Non-invasive joint distractor
•Air contrast arthrogram

14. Imaging – Selective injections
•When there is >1 clinical/
x-ray finding suggesting
possible multiple foci of pain
•Arthrogram confirms location
•LA & steroid injection
•Studies (Khoud et al) show
correlation with injection and
results from arthrodesis

15. Imaging - MRI
•Limited value in OA
•No separation of joint
•Standard magnets do not catch
enough slices across the joint

16. Conservative treatment
•No pro/retrospective trials
•NSAIDS
•Steroid injections – negative effects on tissues
•Mechanical unloading
Moulded AFO
Rocker sole shoe
SACH

17. Operative treatment
Options: Arthroscopic debridement
diagnostic, buys time
suitable for focal lesions
Peri-ankle osteotomies
for focal OA/osteophytes
can create secondary deformities
Arthroplasty
need near normal coronal alignment
Arthrodesis
tried and tested workhorse of surgical
reconstruction
Ankle joint distraction
newer, unproven technique

18. Ankle arthrodesis
•Based on premise that stopping movement at ankle removes painful stimuli
•Pain relief with fusion more reliable than other strategies
•Reported fusion rates vary – 60-100 %
•Low secondary re-operation rates – non-union, hard-ware removal
•Some functional limitation after fusion – shoe-wear modification common
e.g. Rocker sole and SACH
•Fusion result – Patient less able to effectively dissipate forces through the leg
Secondary arthrosis in 50% fusions within 7 years

19. Ankle arthrodesis – Principles
1.Alignment
Review whole extremity
- Correct valgus OA knee first
- Sagittal alignment:
aim for a plantigrade foot
- Coronal alignment:
biomechanics dictate valgus/varus
position
- Rotational alignment:
10° external

20. Ankle arthrodesis – Principles
1.Alignment
Fusing the ankle in a position which everts the subtalar joint gives a flexible
mid-foot, therefore we aim to fuse with 5-7° hind-foot valgus

21. Ankle arthrodesis – Principles
2. Respect the soft tissues
3. Avoid local cutaneous nerves
4. Remove all cartilage
5. Feather into bleeding sub-chondral bone
6. Create congruous cancellous surfaces that can be opposed
7. Use bone graft only to fill large defects
8. Align the hindfoot to the extremity and forefoot to obtain a plantigrade foot
9. Rigidly internally fix

22. Ankle arthrodesis- Mann’s technique
•Lateral, trans-fibular approach
•Exploits internervous plane between sural and
superficial peroneal nerves
•Oblique fibular osteotomy, beveled edge
•Distal fibula excised – can use for bone graft
•Sagittal saw cuts and feathering of tibia and talus
•Medial approach to prepare medial malleolus
•Resection of distal tibia and malleolus as
necessary to appose (7 non-unions, 3 delayed
unions with > 1cm resection of MM !)
•2 parallel cannulated cancellous screws placed
from sinus tarsi into tibia, engaging tibial cortex

23. Ankle arthrodesis- Mann’s technique
•Drain, layered closure, bupivacaine, plaster then popliteal block
•NWB 6/52, FWB in cast 6/52, R/O cast 12/52
Average fusion time = 14/52 (88%)
Non-union rate = 12%
Revision fusion for non-union, average fusion time = 23/52 (75%)
Patient satisfaction post-op: 70% satisfied
18% satisfied with reservation
12% dissatisfied (4 pain, 2 non-union, 1 limp
1 wound infection)
77% no shoe modification
16% rocker shoe
7% AFO
In 3 years 20% have clinical/x-ray signs of adjacent arthrosis, 2 required subtalar
fusion

24. Ankle arthrodesis- the anterior approach
•Exploits interval between EHL and EDL
•Superficial peroneal nerve retracted laterally with deep
neurovascular bundle
•EHL retracted medially
•Deepened to periosteum
•Closed in layers:
•Periosteum
•Ext retinaculum
•Subcutaneous tissue
•Skin

25. Arthroscopic ankle arthrodesis
Developed in 1980’s
Rapid healing
Low non-union rates
Indications:
Well aligned ankle OA
Rheumatoids are good candidates
Patients with increased risk of healing problems
Contra-indications:
Stiff immobile ankle
Need for > 5° re-alignment
Focal bone loss

26. Arthroscopic ankle arthrodesis- setup
•Supine, GA, muscle relaxant
•+/-ankle distractor
•Water pump
•4.5mm scope and shaver
•Marked landmarks
•Medial port, medial to Tib. Ant
•Injection of saline medially
•Introduced with blunt dissection
•Distend capsule with pump
•Anterior synovectomy

27. Arthroscopic ankle arthrodesis
•All articular cartilage shaved
•Burr to make pock-marks across
joint surface
•Joint congruity maintained
•Can improve access with mini-
arthrotomy
•Tourniquet deflated to check for
adequate bleeding

28. Arthroscopic ankle arthrodesis
Screw position: 2 large cannulated, partially-threaded cancellous screws over
k-wires
1st
screw: Posteromedial in tibia to antero-central in talus, 3 cm above joint
2nd
screw: Antero-lateral in tibia to postero-central in talus
Mann includes a syndesmosis screw + lateral bone graft

29. Arthroscopic ankle arthrodesis – results

30. Arthroscopic ankle arthrodesis – results
•At least 15 case series in 15 years
•Myerson: union at 8.7/52 in arthroscopic group
union at 14.5 weeks in open group
•6 studies reporting fusion times of <7 weeks
•Several studies reporting fusion rates of 90-100%
•Ankles with significant deformity/AVN fall to open group
•Shorter average hospital stay – 1day arthroscopic, 4 days open

31. Complications of ankle arthrodesis
•Infection
•Neurovascular injury
•Delayed and non-union
•Malalignment:
Dorsiflexion – heel pad stress
Plantar flexion – back knee thrusting gait
Varus - stiff mid-foot
Valgus – stress to medial aspect of knee
Int/external rotation
•Painful hardware requiring removal
•Subtalar joint penetration, OA

32. Total Ankle Replacement
Disappointing early results, few studies
Early cemented implants – patient satisfaction as low as 20%
Factors for loosening: Poor patient choice: pre-op mal-alignment
Highly constrained, cemented designs
Early-learner surgeons
“Worrisome” number of minor and major complications.........
Of 9 surgeons reporting their 1st
10 cases (Salzman et al): 19 intra-op complications
7 revision surgeries <2yrs
Myerson et al. In first 25 they had 10 significant intra-operative complications
In second 25, only 2 intra-operative complications

33. Total Ankle Replacements - Designs
Mobility (Dupuy) AES Ankle Evolutive System
(Biomet)
SALTO

34. Total Ankle Replacements - Designs
Hintegra (New Deal) Ramses France MBA
Buechel Pappas Low Contact Stress LCS
(Endotech)

35. STAR – Scandinavian Total Ankle
Replacement
Total Ankle Replacements - Designs

36. Special cases – AVN of the Talus
No series comparing results for symptomatic AVN
Mann’s tactic:
If AVN focal – Core decompress
and graft
If AVN global - Fusion for collapse
If no collapse, potential for spontaneous resolution
Or, oral bisphosphonates, US bone stimulator,
and PTB cast- off loads the ankle.

37. AVN of the Talus – Ankle arthrodesis
• Principles are:
Confirm painful joint with injection
Resect entire necrotic segment
Autogenous bone graft as biostimulant
Rigid internal fixation – plates, screws, nail, ex-fix
•Posterior approach to the ankle – less disruption to residual blood supply
•Through Achilles, FHL reflected, posterior ligaments excised +/- fibula resection
•Necrotic bone removed, residual talus prepared in usual way
•Autogenous bone graft- iliac crest
•Relative stability with retrograde, locked I.M nail

38. Newer techniques - Distraction for Talar AVN

39. Revascularization and osteopaenia of Talus after distraction
Symptom free at 6 months, no collapse, joint space preserved

40. Neuroarthropathy
•End-stage, uncommon problem
in long-standing diabetes
•Often serious comorbidity
•High incidence of limb-threatening
complications
•Charcot patients are osteoporotic
•Traditional fixation methods difficult
•Fix the patient, not just the ankle – Long-term orthotics vs BKA for failed surgery
•Surgery indicated : If uncontrolled, intractable coronal plane instability
Locking plates for unidirectional instability
I.M. Nail – tibiocalcaneal fusion for polyaxial instability

41. When things go wrong...........
Arthrodesis-
Non-union: Smokers (4x at risk of non-union)
Elderly
Immunosuppressed
History of open trauma or infection
Poor soft tissues
Poor compliance
Less common after arthroscopic arthrodesis
When is a non-union, a non-union .....9 months, 1 year...?
Principles of treatment: Deal with patient expectation, warn of BKA
Educate, ensure compliance
Rule out infection
Minimise soft tissue stripping
Restrict weight-bearing

42. When things go wrong...........
Arthrodesis
Mal-union Varus/valgus/equinus
Treated with closing wedge osteotomies
Recommend Ilizarov/TSF
2°Subtalar OA Most common joint to develop OA after ankle fusion
All have it on x-rays after 20 yrs
Patients tend to “vault” over the foot in stance phase
Overloads subtalar joint- OA
Treatment = subtalar joint fusion

43. Failed ankle replacement
•Infection
•Component
instability
•Deformity
•Subsidence
•Polyethylene
failure

44. Infected ankle replacement
Prevention: Don’t implant in those with:
Multiple previous surgeries
On steroids
Dermatological conditions
Vascular insufficiency
Meticulous soft tissue handling and haemostasis
Multilayer closure
High elevation of foot
Treatment: superficial wound breakdown, no infection – dressings, Abx
as above plus wound infection – joint aspirate +/- proceed
Wound breakdown to joint – exchange poly +/- EDB flap
Late, deep infection – implant removal and delayed fusion

45. Incongruent, unstable TAR
• Studies show pre-op incongruence
leads to 10x risk of revision to fusion
for instability and deformity for edge-
loading