Table 4 Detailed overview of articles regarding plantar plate integrity and MTP joint stability

Bhatia (1994) ¹

Determine anatomical restraints to dislocation of the 2nd MTP joint and assess biomechanical efficacy for a common stabilizing technique.

25 FF cadaveric feet

(disarticulated at ankle; long flexor tendons preserved at medial malleolus)

Universal testing machine:

Bionix 858, MTS systems Minneapolis, Minnesota.

Hindfoot was transfixed with an aluminum jig. A nylon block was secured to dorsum of the 2^nd metatarsal and a K-wire passed transversely through the proximal phalanx.

Each load cycle was repeated 4x.

Vertical load, measuring dorsal displacement of the proximal phalanx.

5 N preload applied, followed by a constant vertical displacement of 2 mm/min.

Load–displacement curves were measured.

Mean force required to dislocate the toe was:

Group A: 26 N (SD 5.32; 22–34 N) after division of the PP

Group B: 20 N (SD 3.5 N; 15–23 N) after division of the collateral ligaments

Group C: Division of both the PP and collateral ligaments created an unstable joint that dislocated at an applied mean load of 8 N (SD ± 4.74; 5–10 N)

The collateral ligaments and the PP are the main stabilizers of the MTP joint.

Cooper and Coughlin (2011) ⁴

Elucidate the necessary dissection toe expose and potentially repair lesions of the PP trough a dorsal approach.

8 FF cadaveric specimen

(below the knee amputated, examined range of motion & deformity)

4 cm incision dorsal approach; extensor tendon z-tenotomy with dorsal capsulotomy.

Released from base of proximal phalanx vs released from metatarsal head

McGlamry metatarsal head release and Weil osteotomy vs Weil osteotomy

(Horizontal) Measurement of total distraction of metatarsal head and proximal phalanx base.

After each step fluoroscopic and digital photography to determine amount of exposure of plantar plate gained by each step.

Dorsal capsulotomy of the 2nd MTP joint with collateral ligament release off of the proximal phalanx base, then combined with a subcapital oblique metatarsal osteotomy provided an average 8–8.5 mm exposure.

Little improvement of visualization of the plantar plate after use of theMcGlamry elevator for plantar release.

PP exposure is best obtained by releasing collateral ligaments off of proximal phalanx in combination with a subcapital oblique osteotomy.

Suero, et al. (2012) ²⁰

Hypothesis: isolated sectioning of the PP would result in greater dorsal translation compared to isolated sectioning of the MCL, LCL, or EH, and that combined injury to two or more structures would result in greater dorsal translation compared to isolated PP injury.

54 FF toes of 18 cadavers

(from which the 2^nd, 3^rd and 4^th toes were resected at base of metatarsal)

Two most distal phalanges were excised. Potted phalangeal end of the specimen was affixed to a clamp, attached to the load cell of a hydraulic load frame (MTS Systems Copr., Eden Prairie, MN)

Potted base of metatarsal attached to the piston of the load frame.

Vertical load, measuring dorsal translation of the proximal phalanx.

30 N axial load in plantar-dorsal direction, 0.5 N/sec

Mean dorsal displacement for intact MTP joint: 10.6 mm (SD 3.03 mm)

Mean dorsal displacement after sectioning:

PP: 19 % (SD 13 %)^a

EH:11 % (SD 5 %)

MCL: 13 % (SD 7 %)

LCL: 17 % (SD 7 %)

MCL + LCL: 37 % (SD 18 %)^a

EH + MCL + LCL: 45 %

PP + MCL + LCL: 63 % (SD 54 %)^a

PP is main restraint for dorsal MTP joint translation.

Injury to the plantar plate or combined injuries to the plate, EH, MCL, LCL appear to cause significant instability, suggesting a more aggressive treatment.

Chalayon, et al. (2013) ³

Compare intact sagittal plane stability (superior subluxation, dorsiflexion, plantarflexion) of lesser MTP joints.

Quantify role of PP for sagittal plane stability.

4 FF cadaveric specimen

(3 male, death range 48–63 y)

(transected ± 25 cm proximal to the plantar surface of the foot

-Delrin mounting plate, allowing unencumbered plantarflexion motion, secured to calcaneus and secured to 2.54 cm thick aluminum platform mounted to base plate of materials testing system. Two custom fixers designed and fabricated from ABS plastic using a rapid prototype machine; and aluminum wire, 18-gauge, drilled in bone and into fixer.

Each specimen was displaced to 80 % of determined physiological range, and load data were recorded at 100 % of full physiological motion for each motion axis.

Displacing with a 25-mm moment arm measured distally from the center of rotation of lesser MTPJ.

No significant differences measurable between the stability of intact lesser toes. Overall mean stability of intact lesser MTPJs:Superior subluxation: 3.03 ± 0.93 N/mm

Dorsiflexion: 2.07 ± 0.38 N/mm

Plantarflexion: 0.42 ± 0.06 N/mm.

Disruption of PP significantly (P ≤ 0.001) decreased stability by an average in:

Subluxation: 23 ± 5 %

Dorsiflexion: 34 ± 9 %

Plantarflexion: 26 ± 11 %

Data from this study indicated that PP significantly contributed to the sagittal plane stability of the lesser MTP joints.