Lesser metatarsophalangeal joint instability: Diagnosis and treatment of plantar plate tears

Issue: October 2015

ByMichael J. Coughin, MD

ByDavid M. Macias, MD

Historically, the term metatarsalgia has been used to describe generalized forefoot pain. However, this term shines no light on the exact pathology causing pain. A plantar plate tear, leading to lesser metatarsophalangeal joint instability, is a common cause of metatarsalgia. Disruption of the plantar plate is most often attritional, but may occasionally be acute in origin. Multiplanar deformity of the metatarsophalangeal joint may develop, leading to the classic “crossover toe.”

The common symptoms associated with lesser metatarsophalangeal (MTP) joint instability are pain on the plantar aspect of the involved lesser MTP joint, plantar and digital swelling, and lesser MTP joint malalignment. Pain and tenderness can be localized to the plantar aspect of the forefoot at the involved lesser MTP joint. While the second MTP joint is most commonly involved, the third and fourth digits may be involved as well. This pain may be difficult to differentiate from a neuroma, especially when no deformity is present. Sequential injections may be used to help decipher the exact location of pain. Early in the course of a plantar plate tear, the only clinical sign may be swelling of the MTP joint. As the tear progresses, however, deformity in the sagittal and coronal plane may occur.

A drawer test for MTP joint instability may be performed by placing a dorsally directed force on the proximal phalanx. This test has a high sensitivity and specificity for plantar plate tears. A positive test provokes pain, but subluxation may be felt as well. Decreased plantar flexion strength of the involved toe is a common finding with a plantar plate tear. This can be quantified by the “paper pull out test” where the patient attempts to hold a thin strip of paper under the affected digit, and the clinician pulls the paper out from under the toe. A positive test occurs when the patient is unable to plantar flex the digit to keep the tissue beneath the involved toe, indicating decreased plantar flexion strength. A negative test is noted if the paper tears when being pulled out. A hammertoe is a common deformity that may develop at the proximal interphalangeal joint concurrently with a plantar plate tear.

Surgical grading of plantar plate tears include (A) grade I (< 50%), (B) grade II (> 50%), (C) grade III (vertical tear), (D) grade IV (complete tear) and (E) grade V (complex tear).

All patients with suspected plantar plate tear obtain standard AP and lateral weight-bearing radiographs to assess the MTP joint alignment and the presence of any bony pathology. Arthrography may also be considered. For this soft tissue injury however, MRI is the most reliable imaging modality for noninvasively evaluating a plantar plate tear. There is a normal decussation of the plantar plate in the middle of its attachment to the base of the proximal phalanx which can be confused with a tear. Plantar plate tears most commonly appears laterally. In our current practice, we do not routinely order an MRI if the physical examination is consistent with a plantar plate tear.

Conservative treatment includes shoe wear modification, the use of a metatarsal pad, addition of a graphite insole, taping of the toe and an intra-articular corticosteroid injection. These measures may or may not decrease pain, however, they will not correct deformity or the underlying problem of the plantar plate tear. Patients with subluxation or dislocation will likely receive little or no relief from these interventions.

The development of both a clinical staging and surgical grading systems have enabled us to define the magnitude and pattern of plantar plate tears, and to assist in the preoperative planning of lesser MTP joint instability (Figure 1).

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Prior to defining plantar plate pathology, treatment options attempted to achieve stability of the MTP joint using indirect methods. Treatment options included MTP joint synovectomy, soft tissue capsular and ligamentous release and reefing, extensor and flexor tendon transfers, phalangeal and metatarsal osteotomies, and even digit amputation. However, none of these surgical techniques treat the plantar plate tear. Because of its anatomic location at the plantar surface of the MTP joint, the plantar plate is the main structure resisting MTP joint displacement. Working in combination with the collateral ligaments, the plantar plate provides MTP joint stability.

Operative techniques for plantar plate repair have changed over time. Some surgeons have advocated a plantar approach, but exposure of multiple joints is difficult and there is a real risk of painful scar formation. A dorsal incision also may be used, allowing exposure of two adjacent MTP joints through one skin incision. Several authors have reported satisfactory results of plantar plate repairs done through a dorsal approach.

The crossover second toe deformity was originally described in 1987. Since that time, great strides have been made in our clinical and surgical understanding of lesser MTP joint instability. Currently, we feel the best treatment is a direct repair with capsular advancement performed through a dorsal approach. We have noted satisfactory early results using this surgical technique.

Placement of the suture with the Mini-Scorpion into the plantar plate.

A close-up of the suture technique is shown.

Images: Coughlin MJ

The patient is placed supine with a bump beneath the ipsilateral hip. An Esmarch ankle tourniquet is used. An incision approximately 3 cm long is centered in the webspace of the affected toes; the exposure is carried sharply through the skin and into the interval between the extensor tendons which are retracted. The MTP joint capsule is opened dorsally. The collateral ligaments are routinely released from the base of the phalanx so as to not disrupt blood supply to the metatarsal head. A McGlamry elevator is placed into the joint and slid proximally beneath the metatarsal head releasing the proximal capsule. Usually, a palpable release of the proximal plantar plate is felt. This maneuver allows for some excursion of the plantar plate distally.

If necessary for improving visualization or to improve the metatarsal cascade, a Weil osteotomy is then performed in which the metatarsal head is moved proximally and then pinned in place with a vertical 0.062-mm Kirschner wire.

A joint distractor is placed over the metatarsal pin and a pin is placed in the proximal phalanx engaging the distractor. As the distractor is spread, tension is placed across the joint and the plantar plate is visualized. Any remaining attachment of the plantar plate to the proximal phalanx is then released, but the underlying flexor tendon is protected.

Two nonabsorbable #0 sutures are then passed transversely through the plantar plate. There are numerous devices for passing this suture. Our preference is the Mini-Scorpion (Arthrex) (Figure 2), however for extremely tight joints a curved manual suture passer (PigTail; Arthrex) is helpful. A Viper (Arthrex) suture passer may be used as well. After the sutures are placed (Figure 3), medial and lateral drill holes are made in the base of the proximal phalanx (Figures 4 and 5). A suture passer brings one limb of each suture through each drill hole. The joint is then manually compressed and held in 16° of plantar flexion while the sutures are tied over the bony bridge on dorsum of the proximal phalanx.

The mattress suture is in plantar plate.

Placement of parallel mattress sutures in plantar plate is shown.

If a Weil osteotomy was performed, it is aligned appropriately and two spin screws (to prevent rotation) are placed across the osteotomy at the distal metatarsal. If there is still deformity in the transverse plane, capsular reefing may be performed on the deficient side. A stable repair should result in elimination of any preoperative drawer. Routine skin closure is then performed with nylon suture and a gauze and tape compressive dressing is applied.

The patient is allowed to weight-bear on the heel in a postoperative shoe as soon as the nerve block has worn off. At the 2-week postoperative visit, the patient is instructed on strengthening and range of motion exercises. Heel weight-bearing in the postoperative shoe is continued for 6 weeks and then transition to athletic shoe wear is permitted.

References:
Barg A, et al. Foot Ankle Int. 2012;doi:10.3113/fai.2012.0877.
Blitz NM, et al. J Foot Ankle Surg. 2004;doi:10.1053/j.jfas.2004.05.009.
Bouche RT and Heit EJ. J Foot Ankle Surg. 2008;doi:10.1053/j.jfas.2007.12.008.
Brunet JA and Tubin S. Foot Ankle Int. 1997;doi:10.1177/107110079701800706.
Cooper MT and Coughlin MJ. Foot Ankle Int. 2011;doi:10.3113/fai.2011.0294
Coughlin MJ. J Bone Joint Surg Br. 82:781-790. 2000.
Coughlin MJ. Foot Ankle. 8: 29-39. 1987.
Coughlin MJ. Surgery of the Foot and Ankle. Phila., PA, Mosby Elsevier Inc., 1: 363-464.
Coughlin MJ: Foot Ankle.1993;doi:10.1177/107110079301400601.
Coughlin MJ. Orthop Clin North Am. 20:535-551. 1989.
Coughlin MJ: J Musculoskeletal Medicine. 39-48. 1987.
Coughlin MJ, et al. Phys Sportsmed.2011;doi:10.3810/psm.2011.09.1929.
Coughlin MJ, et al. Foot Ankle Int.2012;doi:10.3113/FAI.2012.0133.
DuVries HL. JAMA. 160:728. 1956.
Ford LA, et al. J Foot Ankle Surg. 1998;doi:10.1016/S1067-2516(98)80114-2.
Gallentine JW and DeOrio JK. Foot Ankle Int. 2005;doi:10.1177/107110070502600502.
Gregg J, et al. Foot Ankle Surg. 2007;doi:10.1016/j.fas.2007.01.001.
Haddad SL, et al. Foot Ankle Int. 1999;doi:10.1177/107110079902001205.
Johnston RB 3rd, et al. Foot Ankle Int. 1994;doi:10.1177/107110079401500508.
Kaz AJ and Coughlin, MJ. Foot Ankle Int. 2007;doi:10.3113/fai.2007.1223.
Klein EE, et al. Foot Ankle Int. 2013;doi:10.1177/1071100712471825.
Klein EE, et al. Foot Ankle Spec. 2012;doi:10.1177/1938640012463061.
Klein EE, et al. Foot Ankle Spec. 2013.doi:10.1177/1938640013484795.
Mann RA and Mizel MS. Foot Ankle. 1985;doi:10.1177/107110078500600104.
Mendicino RW, et al. J Foot Ankle Surg. 2001;doi:10.1016/S1067-2516(01)80021-1.
Myerson MS and Jung HG. Foot Ankle Int. 2005;doi:10.1177/107110070502600903.
Nery C, et al. Foot Ankle Int. 2012;doi:10.3113/fai.2012.0301.
Powless SH and Elze ME. J Foot Ankle Surg. 2001;doi:10.1016/S1067-2516(01)80005-3.
Sarrafian SK and Topouzian LK. J Bone Joint Surg Am. 51:669-679. 1969.
Sung W, et al. J Foot Ankle Surg. 2012;doi:10.1053/j.jfas.2012.05.009.
Trepman E and Yeo SJ: Nonoperative treatment of metatarsophalangeal joint synovitis. Foot Ankle Int. 16: 771-777. 1995;doi:10.1177/107110079501601206.
Weil L Jr., et al. Foot Ankle Spec. 4. 2011;doi:10.1177/1938640010397342.
Yu GV, et al. J Am Podiatr Med Assoc. 92:182-199. 2002.
Nery C, et al. Foot Ankle Int. 2014;doi:10.1177/1071100714539659.

For more information:
David M. Macias, MD, can be reached at Columbus Orthopaedic Clinic, 670 Leigh Dr., Columbus, MS 39705; email: thefootmd@gmail.com.
Michael J. Coughin, MD, can be reached at Saint Alphonsus Regional Medical Center, Coughlin Foot and Ankle Clinic, 1075 N. Curtis Rd. Suite 300, Boise, ID 83706; email: david.macias@sarmc.org.

Disclosures: Macias has no relevant financial disclosures. Coughlin reports he is a paid consultant for and receives royalties from Arthrex.