Subtle Deformities and The Role of the Joint Capsule

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Subtle Deformities and The Role of the Joint Capsule Joshua Harris, MD

August 7, 2016

DisclosuresResearch support: Smith & Nephew, Depuy Synthes, Ossur;

Consultant: Smith & Nephew, NIA Magellan;Royalties: SLACK, Inc.;

Editorial board: Arthroscopy, Arthritis Research UK;Committees: AANA, AOSSM, AAOS

Goals

• Subtle deformities– Acetabular

• Borderline dysplasia– Femoral

• Version• Neck-shaft angle

• Capsule– Normal anatomy– Pathomechanics

• Iatrogenic• Hypermobility

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Subtle deformities

Understand normal anatomyMinimum Maximum

Neck‐shaft angle 120° 135°

Lateral CEA 25° 40°

Anterior CEA 25° 40°

Tonnis angle 0° 10°

Extrusion index 0% 25%

Alpha angle n/a 50‐55°

Head‐neck offset 8 mm n/a

Offset ratio 17% n/a

Sharp’s angle 33° 38°

Center‐troch distance ‐17 mm 10 mm

Joint space 2 mm n/a

Hip‐center position n/a 10 mm

Offset 41 mm 44 mm

Minimum Maximum

Crossover sign + ‐

Ischial spine sign + ‐

Posterior wall sign + ‐

Coxa profunda + ‐

Protrusio acetabulae + ‐

Tonnis OA 0 3

AIIS type 1 3

Congruency Congruent Incongruent

Shenton’s line Intact Broken

• Treat patients, not x-rays

Asymptomatic X-rays

• Cam: 37% prevalence – Using 50-55° threshold– 55% athletes– 23% non-athletes

• Pincer: 67% prevalence – 2/6 radiographic markers

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Laxity = AsymptomaticInstability = Symptomatic

Laxity ≠ Instability

Understand pathology

Subtle deformity - Femur

• Version – both femoral and acetabular – McKibbin index (version), Omega surface (5 parameters)

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Version vs ROM

• 221 patients; mean age 33 years– COTAV – combined femoral torsion acetabular version

• Femoral anteversion and acetabular anteversion had greatest IR (p<0.05)

• Femoral retroversion and acetabular retroversion had lowest IR (p<0.05)

Subtle deformity - Femur

• Can induce both instability and impingement

1. Excessive femoral retroversion• Anterior impingement, posterior instability

2. Excessive femoral anteversion• Anterior instability, +/- posterior impingement

3. Excessive acetabular retroversion• Anterior impingement, posterior instability

4. Excessive acetabular anteversion• Anterior instability, +/- posterior impingement

Subtle deformity - femur

• What is normal ?8° to 20°

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Version outcomes

• Excessive version ↑↑↑ OA risk

Version outcomes

• 100 M, 88 F; mean age 35 years• Mean femoral version 9°

– Version vs ER (r= -.21; weak, but p<0.05)– Version vs IR (r= +.23; weak, but p<0.05)

• Femoral version >15° 2.2X more likely to have anterior tears beyond 3 o’clock

• Higher version (p<0.05) in psoas release patients

Version outcomes

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Version outcomes

• 180 hips; mean femoral version 10°– >15° - more anterior 3 o’clock labral tears– 5° - 15°– <5°

• Higher (p<0.05) version in psoas release patients• No difference (p>0.05) in PRO’s

Version outcomes

• 67 hips; – Low/normal version = <25°– High version = >25°

• High version >> worse pre-op HOS-SSS (p<0.05)• High version >> worse post-op mHHS (p<0.05)

Version outcomes

• 278 hips; mean femoral version 8°• Anterior 3 o’clock tears

– Version >18° = 30%– Version -2° to 18° = 78%– Version <-2° = 73%

• No difference in PRO’s (p>0.05)

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Neck-shaft angle – Normal?

• Pelvic CT – 400 patients– Mean NSA 130°

• Systematic review – 6,319 hips– Normal healthy adults = 129°– OA adults = 132°

Neck-shaft angle

• 47 professional classical dancers; mean age 24y

Neck-shaft angle

• AP and “splits” x-rays• Significant negative correlation (p=0.02) with

subluxation distance and NSA (r= -0.33)

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NSA – Troch-pelvic FAI

Permissive limb ER

Intentional limb IR

NSA Outcomes

Borderline dysplasia –What is it?

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Borderline dysplasia

• Define it:– LCEA: 20° - 25°– ACEA: 20° - 25°– Tonnis angle: 10° - 15°

Borderline dysplasia

• Potential hip instability– Pre-op – Post-op

Borderline dysplasia -Outcomes

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• Non-arthritic dysplasia – PAO +/- arthroscopy• If arthroscopic manage BD:

– Preserve labrum– Preserve capsule– Preserve iliopsoas

• No iatrogenic over-resection of the rim• Do not ignore femur !!! (combined effects)• Outcomes may be as good

– Possibly worse – Possibly catastrophic


• Pre-operative or iatrogenic dysplasia or BD present in 5/11 (45%) of macro-instability cases

• Capsular closure performed in 2/10 interportal and 1/1 “T” capsulotomy

Role of the capsule

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Capsule – In the lab

Take-home points:*Unrepaired capsulotomies – instability*Repaired capsulotomies – normalizes stability

Capsule - Pathology

• Native– EDS, hypermobility

• Iatrogenic– Unrepaired capsulotomies

Capsule - Presentation

• Pain• Apprehension/fear• Difficult RTS

*** Extended, ER*** Abducted, ER

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Capsule – Indications

Capsule – Technique


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Capsule – Outcomes

Conclusions

• Subtle deformities (bony, soft tissue) are common

• May lead to either instability or impingement • High index of suspicion – you have to look for it• Correct identification and management to

optimize outcomes

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Subtle Deformities and The Role of the Joint Capsule