http://upload.orthobullets.com/topic/7016/images/2nd MTP dislocation - courtesy Richardson_moved.jpg
http://upload.orthobullets.com/topic/7016/images/plantar plate.jpg
http://upload.orthobullets.com/topic/7016/images/mri plantar plate.jpg
http://upload.orthobullets.com/topic/7016/images/Weil procedure - courtesy Richardson_moved.jpg
Introduction
  • Most frequent monoarticular synovitis of the MTP joints
  • Epidemiology
    • risk factors
      • elongated second metatarsal relative to the first metatarsal
        • Morton Foot
      • hallux valgus deformity
  • Pathoanatomy
    • synovitis causes the capsuloligamentous apparatus of the MTP joint to become stretched
      • stretching leads to instability
        • instability leads to deformity
    • attenuation of plantar plate
      • extension of MTP joint
      • sagittal plane deformity
      • associated with cross-over toe deformity  
    • MTP instability can lead to dorsal dislocation of MTP joint 
      • predisposition to hammer toe deformity
Anatomy
  • Cadaveric cross section of plantar plate  
  • MRI of plantar plate  
Presentation
  • Symptoms
    • pain
    • warm joint
    • fullness of joint
  • Physical exam
    • pain and tenderness
      • may have pain in second web space
      • tenderness may be worse plantarly over plantar plate or over dorsal capsule
      • caused by inflammation or extrinsic pressure on interdigital nerve
    • global swelling of MTP
    • motion
      • decreased plantar flexion
    • deformity & motion
      • deformity is often passively correctable in the predislocation stages
      • instability, if present, can be demonstrated with the dorsal drawer test
      • if able to dorsally sublux then attenuation of plantar plate present
      • as deformity progresses second toe may cross over adjacent toe in a varus or valgus deformity
        • disruption of a collateral ligament and the plantar plate
        • "cross over toe deformity"
Imaging
  •  Radiographs
    • recommended views
      • weight-bearing AP and lateral views of foot
    • findings
      • widening or medial-lateral joint space imbalance of second MTP joint
      • dorsal subluxation of MTP joint
        • may appear like joint space narrowing or overlapping of the proximal phalanx on distal metatarsal head
      • varus or valgus deformity of toe
  • MRI
    • indications
      • if diagnosis unclear
      • quantify the extent of plantar plate or ligamentous disruption 
Differential
  • Morton's neuroma
    • may mimic Mortons neuroma
    • important to differentiate MTP synovitis from interdigital neuroma because a steroid injection into the interdigital space may weaken the capsuloligamentous structures at MTP joint leading to progressive deformity
Treatment
  • Nonoperative
    • activity/shoe wear modifications, NSAIDs, external support of MTP joint
      • indications
        • first line treatment
      • technique
        • external support with crossover taping or Budin-type toe splint
        • nonoperative treatment should last 10 to 12 weeks
        • subsequently avoid shoes that aggravate symptoms
  • Operative
    • synovectomy
      • indications
        • no deformity
        • failure of nonoperative treatment
    • distal oblique shortening MT osteotomy (Weil procedure) 
      • indications
        • fixed deformity with long second metatarsal
      • technique
        • preserves joint
        • rebalances metatarsal cascade
        • relaxes plantar plate and rebalances alignment
    • FDL-to-EDL tendon transfer (Girdlestone-Taylor) or MTP capsular release with extensor tendon lengthening
      • indications
        • fixed deformity and NO long second metatarsal
        • sagittal deformity
Complications
  • Vascular compromise
    • if correcting a chronic dislocation the soft tissue, including vasculature, can contract
    • stretching of the vasculature can compromise flow
    • procedure may need to be reversed to save digit
 

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Questions (1)

(OBQ12.130) Plantar plate deficiency is most commonly associated with which of the following deformities shown in Figures A-E? Review Topic

QID:4490
FIGURES:
1

Figure A

49%

(940/1935)

2

Figure B

4%

(76/1935)

3

Figure C

3%

(54/1935)

4

Figure D

36%

(703/1935)

5

Figure E

8%

(151/1935)

Select Answer to see Preferred Response

PREFERRED RESPONSE 1

Plantar plate deficiency is most commonly associate with cross-over toe deformity, which is shown in Figure A.

The tendency with weight-bearing is to displace the proximal phalanx dorsally. The plantar plate and the intrinsic flexors (interossei and lumbricles) resist this force and pull the proximal phalanx back into a neutral position at the MTP joint. Chronic or acute hyperextension forces on the proximal phalanx cause stretching and/or attenuation of the plate, resulting in instability. Ultimately, this instability, in conjunction with collateral ligament attenuation, can lead to the clinical condition where the second toe crosses either under or over the hallux.

Shirzad et al. review the presentation, anatomy, and treatment of common lesser toe deformities. They specifically outline the nonsurgical and surgical treatment for MTP joint instability, such as that found in cross-over toe. Isolated soft-tissue procedures or osteotomies can be performed based on the degree of instability present and joint congruence.

Illustration A shows the plantar plate, and how laxity of this structure leads to MTP joint laxity and toe deformation.

Incorrect Answers:
Answer 2: This image shows the classic radiographic appearance of Freibergs infraction which is not associated with plantar plate pathology.
Answer 3: This clinical image shows a Lisfranc injury. This condition frequently occurs in the setting of acute trauma, and is not typically related to plantar plate deficiency.
Answer 4: This clinical image shows a classic claw-toe deformity of the second toe. This is caused by weaker intrinsic
forces which give way to the stronger extrinsic forces. MTP joint extension is caused by the action of the stronger EDL tendon on the extensor sling.
Answer 5: This clinical image shows a classic curly-toe deformity. This is caused by contracture of the FDL and FDB, the etiology of which is unknown.

ILLUSTRATIONS:

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