Plantar plate injury and repair techniques

Plantar plate injury and repair techniques

Plantar plate injury and repair techniques

Yasir Ali, Yogesh Joshi and Asad Syed review the latest literature describing the technological advances that give the best surgical outcomes for plantar plate repair

The Plantar plates are fibro-cartilaginous structures that are vital for the stability of the metatarsophalangeal (MTP) and interphalangeal joints. The stability of these joints can be compromised due to injury to the plantar plates. Technological advancement has made it possible to repair the plantar plate with various new techniques and equipment that are now available. he plantar plate is an important stabilising structure of the metatarsophalangeal joints in the forefoot and its pathology is commonly seen in clinical practice. In this review article, we have tried to elaborate different aspects of the plantar plate pathology in terms of anatomy, patho-aetiology of the plantar plate tear, patient history, clinical examination, radiological investigation and common surgical techniques. We have concluded that plantar plate repair using the dorsal approach, combined with the Weil’s osteotomy and soft tissue release provides the best surgical outcome, in terms of preventing complications, and patient satisfaction.

Anatomy

The plantar plate is a firm fibro-cartilaginous ligament composed of type 1 collagen, which renders it able to withstand the wear and tear of daily life activities. It is attached to the major longitudinal bands of the plantar aponeurosis proximally, to the base of the proximal phalanx distally, and to the collateral ligaments – which consist of phalangeal collateral ligaments (PCL) and accessory collateral ligaments (ACL). It is located deep to the tendons of the flexor digitorum longus (FDL) and brevis (FDB). The plate and the ligaments together provide stability to the MTP and interphalangeal joints in transverse as well as sagittal plane. The difference between the plantar plates at the MTP and interphalangeal joint is that at the MTP joint, the plantar plate blends with transverse metatarsal ligaments (TMLs). The plate attaches loosely to the metatarsal neck but the attachment to the base of the proximal phalanx is very strong. It also receives the fibres from the lumbricals and the interosseous tendons resisting the hyperextension at the MTP joint [1–4].

The plantar plate and the TML together control the splay of the forefoot. The deep plantar fascia and its insertion along the plantar plate and TML control the longitudinal arches of the foot. So, as a result, plantar plates withstand compressive and tensile loads acting on the foot [2].

Patho-aetiology

There are different terms which have been described for second MTP joint pathology. In 2002, Yu & Judge introduced the term pre-dislocation syndrome (PDS), one of the causes being plantar plate tear [5]. Some of the terms mentioned by Shane et al. in their 2013 publication [6] for the similar second MTP joint conditions are:

  • crossover second toe deformity;
  • floating toe syndrome;
  • lesser MTP joint instability syndrome;
  • chronic lesser MTP joint dislocation;
  • second MTP joint dislocation;
  • submetatarsal 2 syndrome; and
  • monoarticular non-traumatic synovitis.

In 2007, after reviewing 169 diagnosed pre-dislocation syndrome patients, Kaz & Coughlin [7] found that the crossover second toe deformity can be seen commonly in women over the age of 50; high-heeled footwear is a risk factor. A positive Drawer’s sign is seen in over 60 per cent of the patients. The second MTP joint is most commonly affected as it has unopposed lumbricals without plantar interossei insertion.

Plantar plate tears usually result from repetitive overload from abnormal forefoot loading patterns resulting from hallux valgus, excessive pronation, short first metatarsal or long second metatarsal; however, Kaz & Coughlin found no correlation between crossover toe deformity and second metatarsal length, hallux vagus angle or intermetatarsal angle [7]. The tear usually arises from the base of the proximal phalanx.

In 2002, Yu & Judge [5] described three stages of pre-dislocation syndrome and these can be seen in Table 1. Sferra & Arndt described five stages of crossover toe deformity in a review article in 2011 [8] and these are listed in Table 2. The plantar plate tear is also graded into [20]:

Grade 1: attenuation (loss of pearly white colour, more yellowish)

Grade 2: buttonhole type (longitudinal tear at maximum weight bearing point)

Grade 3: partial tear (at the point of attachment of plantar plate to proximal phalanx, either medial or lateral; causes deviation of the digit in the opposite direction of the tear)

Grade 4: complete tear (associated with severe degeneration and infiltrative fibrosis of the plate).

Clinical findings

Patients usually present with pain under the ball of the foot, most commonly under the second MTP joint, which might extend to the dorsal aspect of the joint. The pain can be aggravated with dorsiflexion of the joint. Sometimes swelling may be present around the joint involved due to capsular distension and synovitis. Neurological symptoms may also arise as a result of the nerve involvement due to local oedema and inflammation. Crossover toe deformity may also be the presenting complaint.

On examination, most commonly the second MTP joint, may have tenderness on palpation; there may also be associated mild swelling plantarly and dorsally. Commonly, patients may also notice a gradual hammering and an additional transverse plane deformity of the second toe, also called hammer toe deformity and crossover toe deformity respectively. A positive Lachman’s test is pathognomonic of the plantar plate injury, as described by Thompson & Hamilton in 1987 [9]. The test is performed with the phalanx held at 20 degrees of dorsiflexion relative to the metatarsal and the plantar stress is applied. A dorsal displacement of 2mm or 50 per cent joint sublaxation with resulting pain is considered positive.

Investigations include plain radiographs in weight-bearing antero–posterior, lateral and axial views. The importance of MRI imaging in diagnosing plantar plate injury was well described by Yao and colleagues in 1996 [10]. T2 weighted images are of particular use in identifying soft tissue injuries and resultant damage to the articular surface. In 2012, Sung and co-workers [11] prospectively reviewed 41 patients (45 feet) with diagnosed plantar plate tear on MRI scans and compared the results with the intra-operative findings. They also assessed the severity of the tears as described by the coronal and sagittal MRI compared with actual tear intra-operatively using another grading system (Table 3). They found 41 plantar plate tears intra-operatively out of the 45. The specificity and positive predictive value of MRI was 100 per cent; accuracy and sensitivity were 96 per cent and 95 per cent respectively; while the negative predictive value was 67 per cent. Their results have demonstrated that MRI is an accurate imaging modality for diagnosing plantar plate tear.

Treatment

Management can be divided into non-operative and operative treatment.

Non-operative management

Non-operative management is aimed at reducing the pain and stopping the progression of the disease. It includes RICE (rest, ice, compression and elevation). NSAIDs can be useful for the pain. Taping is not recommended in the acute stage injury due to the risk of vascular compromise. A short leg cast with toe spica in slight dorsiflexion is also being used to relieve the pain.

After the acute stage, for the attenuation and buttonhole type injuries, taping of the toe is advocated. Insoles with carbon fibre steel plates can also be used, the goal being to minimise movement of the forefoot.

For a partial tear, the same treatment is recommended, usually with the use of crutches for two weeks. For complete tears, long-term immobilisation in a cast or boot may be necessary, usually for two to six weeks. A single intra-articular cortisone injection can also help alleviate symptoms.

Operative management

Most of the injuries recover with non-operative measures; the failure of conservative therapy with ongoing pain is an indicator that operative intervention may be necessary, as are toe deformities such as crossover toe or hammer toe, generalised synovitis, diminished flexor strength and advanced degeneration of the joint. Pre-operative counselling is of utmost importance.

For chronic synovitis without significant instability that is unresponsive to non-operative treatment, extensor longus lengthening, synovectomy and dorsal capsulotomy can be performed. With the joint instability a joint strengthening procedure should also be added [12].

Transfer of the flexor tendon to the extensor and EDB tendon transfer are other options to strengthen and stabilise the MTP joint and to correct crossover toe deformity. In 1999, Haddad and colleagues reviewed 31 patients (35 feet) who underwent repair of crossover toe deformity either with flexor-to-extensor tendon transfer (rigid stage 3 and 4 deformities) or EDB tendon transfer (stage 1 and 2 and flexible stage 3 deformities) [13]. Out of 31 patients, 24 were completely satisfied with the procedure; 22 patients had no post-operative pain. In 30 feet there was no recurrence and the AOFAS score post-operatively was 85 for all patients. Haddad and co-workers also concluded that stiffness of the joint was a potential complication of flexor to extensor tendon transfer [13]. In 2005, Myerson & Jung [14] carried out a retrospective study of 59 patients (64 feet) with second MTP joint instability, with crossover toe deformity present in 87 per cent of them. FDL transfer was performed as a primary procedure, while an additional Weil’s osteotomy was performed in 45 per cent of cases, proximal interphalangeal joint resection arthroplasty in 34 per cent of patients and proximal interphalangeal joint fusion in 14 per cent of cases. The outcome at the final follow up was improvement in second metatarsal functional status because of the pain relief, although 31 per cent of patients were dissatisfied due to residual stiffness. Myerson & Jung concluded that FDL transfer is an important procedure but should be performed with the complete understanding of the possible complications and patient dissatisfaction [14].

Plantar plate repair using the plantar approach was performed in the past; however, owing to wound healing complications, the amount of dissection and long postoperative immobilisation, most surgeons do not perform this technique nowadays. The direct repair of the plantar plate can stabilise the joint using the dorsal approach described by Cooper & Coughlin [15] in 2011 in their study on eight cadaveric specimens and obtaining the measurements using fluoroscopic imaging and digital photography. They concluded that 8–8.5mm exposure of the plantar plate can be obtained by releasing the collateral ligament from the base of the proximal phalanx and performing sub-capital oblique osteotomy which also minimises the risk of disrupting the blood supply to the metatarsal head.

In 2007, Gregg and colleagues reviewed the results of combined plantar plate repair and Weil’s osteotomy for the instability of the lesser metatarsals [16]. They reviewed 21 patients (23 feet) with unstable and multiple unstable MTP joints who underwent plantar plate repair and Weil’s osteotomy for plantar plate rupture. Twelve feet also underwent concomitant hallux valgus repairs. Upon mean follow up at 26 months, about 78 per cent of the feet (18 feet) had no post-operative pain, 17 per cent had mild pain and only one foot experienced moderate pain. Although most of the rest had only occasional limitation, 13 feet experienced no activity limitations; eight feet had no post-operative stiffness, while 13 had noticeable stiffness. Pre-operatively, varus deviation was present in four lesser metarsals and valgus in three, whereas post-operative deviation was none. In general, 17 were satisfied with the procedure while six were dissatisfied.

Recurrence of MTP joint sublaxation greater than 50 per cent was reported in only one foot. The AOFAS results of the combined procedure were 88.9 compared with the 86.1 for the Weil’s osteotomy alone for relief of metatarsalgia. It resulted in effective pain relief and lesser incidence of residual extension deformity – i.e. floating toe – than with Weil’s procedures alone.

In 2011, Weil and colleagues [17] reviewed 13 patients (15 feet) who underwent combined plantar plate repair and Weil’s osteotomy of the second metatarsal and concluded that post-operative AOFAS scores averaged 85.7 per cent, 85 per cent reported improved function and 77 per cent were satisfied with the surgery. There was significant reduction in pain from 7.3 pre-operatively to 1.7 post-operatively on a visual analogue pain scale. No cases of MTP joint sublaxation post-operatively were reported.

Nery et al. concluded an improvement in AOFAS score from 52 points pre-operatively to 92 points post-operatively after reviewing 22 patients who underwent direct plantar plate repairs, Weil’s osteotomy and lateral soft tissue reefing in 2012 [18]. Post-operatively, elevation, inspection of the wound after 7–10 days, weight bearing with multipurpose surgical shoes for six weeks and removal of K wire in four to six weeks is required.

Repair techniques

Arthrex complete plantar plate repair system (CPR)

After a longitudinal dorsal incision over the second MTP joint and dissection down to the extensor tendons, the second MTP joint is exposed with the help of self-retaining retractors placed deep in between the extensor tendons, and collateral ligaments are released from the base of the proximal phalanx. A McGlamry elevator is used to release the proximal plantar plate, leaving substantial soft tissue on the medial and lateral sides of the metatarsal head, which aids in exposure and advancement of the plantar plate. Weil’s osteotomy is then performed, originating 1–2mm below the dorsal aspect of the metatarsal articular surface.

After the osteotomy is complete, the capital fragment is translated back (5–10mm) using a metatarsal head pusher and stabilised temporarily in the shortened position using a K wire. Visualisation of the plantar plate is then gained using the small joint distractor, and it is stabilised with two K wires – proximal in the metatarsal head and about 5mm distal to the base of the proximal phalanx. The partial tear of the plantar plate is converted into a complete tear as close to the insertion of the plantar plate to the proximal phalanx as possible, taking care to avoid the flexor tendons.

After complete mobilisation of the plantar plate, two horizontal mattress sutures are passed using either the Mini Scorpion DX technique or the Micro SutureLasso Plantar Plate Pigtail technique. The small joint distractor and the K wire in the proximal phalanx are now removed. The phalanx is then plantar-flexed using a right-handed towel clamp, and the plantar edge of the proximal phalanx is roughened to prepare the surface for the reattachment of the plantar plate. Two oblique bone tunnels are then drilled in the proximal phalanx using K wires and sutures are passed through them in a crossing fashion using the suture retrieval funnel.

K wire from the metatarsal head is removed and Weil’s osteotomy is then moved back to anatomical position and fixed with one or two Quick fix screws with 1–2 mm shortening at the osteotomy site. With the toe held at 20–30-degree plantar flexion and reduced at the metatarsal articular surface, sutures are pulled tight and tied over the cortical bridge between the two drill holes, advancing the plantar plate to the base of the proximal phalanx.

Post-operative care

Gauze and tape compression dressing after the surgery and heel weight-bearing in post-operative shoe for six weeks. Physical therapy is initiated at 7–10 days after the surgery, and at day 10 manual exercise commences in the form of passive stretching with increasing plantar flexion. Full weight-bearing is allowed six weeks after surgery in an athletic shoe. Aggressive walking is allowed at eight weeks and jogging or running at 12 weeks as tolerated.

Smith & Nephew HAT-TRICK lesser toe repair system

A dorsal incision is made from mid-metatarsal to the mid-proximal phalanx, protecting the EDL tendon. The MTP joint capsule is exposed by releasing the extensor hood longitudinally on the side of collateral ligament attenuation. Trigger retractor is used to expose the site.

The MTP joint is distracted using the small joint pin distractor and K wires approximately 1cm from the joint. Both the collateral ligaments and the plantar plate are dissected at the metatarsal head taking care of flexor tendons. Residual parts of the collateral ligaments and the plantar plate on the base of the proximal phalanx are removed using the curved blade.

Ligament insertion sites are denuded using the double-ended rasp to promote healing. Four 2-0 ULTRABRAID sutures are now placed in the plantar plate and collateral ligaments (different colours) using the HAT-TRICK DART suture passer and the distractor and K wires are then removed.

Two bone tunnels are drilled in the proximal phalanx contralateral to each other using the phalangeal drill guide; short offset and K wires and sutures are passed through them using the suture shuttle assembly.

Plantar plate and collateral ligament sutures are separated by colours and tensioned using the suture tensioner, until the desired dorsal–plantar stability is achieved. The suture tensioner is then removed and the desired fixation knot is tied to complete the repair.

Post-operative care

For the first six weeks, a light bulky dressing is applied with the MTP joint in slight plantar flexion. The patient can heel weight-bear as tolerable in a post-operative shoe with or without walking aids, with gentle active ankle and MTP joint motion.

In the next 6–12 weeks, weight-bearing is allowed as tolerated in a hard sole shoe and activity is limited to walking only. Low-impact sports can be participated in after 12–16 weeks, and full activities as tolerated after 16 weeks.

Complications [19]

The most common complications associated with plantar plate repair are as follows:

Misdiagnosis, as interdigital neuroma, which requires re-operation for plantar plate repair if neurectomy has initially been performed, as pain continues.

Transfer metatarsalgia, resulting from over-shortening of the metatarsal (1–3mm shortening is usually adequate).

Flexion weakness (metatarsal shortening being the most common cause) can result in residual hyperextension. Limiting the plantar translation and shortening of the metatarsal with aggressive range of motion exercises is the solution.

Joint stiffness, which often improves with time. Early range of motion exercises and flexible footwear helps, otherwise manipulation under sedation and surgical release is required.

Residual pain, which can be prevented by starting the osteotomy in the dorsal cartilaginous surface of the metatarsal head, maintaining the osteotomy parallel to the plantar aspect of the foot and avoiding over-shortening of the metatarsal head.

Recurrence of the deformity, although rare, can occur and requires aggressive procedures such as flexion tendon transfer or metatarsal arthroplasty.

Dorsal contracture, which can be prevented by splinting the toe in plantar flexion for four weeks post-operatively. Early aggressive physiotherapy to strengthen flexor tendons is also required. To correct dorsal contractures, percutaneous capsulotomy and manipulation is performed between four and nine months post-operatively.

Summary

The incidence of the plantar plate tear is increasing and more commonly seen by surgeons. A huge amount of clinical resources are now available to accurately diagnose and treat the plantar plate pathology. History and clinical examination are very important to give clues to the diagnosis. Grading and staging criteria devised by different authors are very helpful as well. MRI remains the most sensitive and accurate diagnostic tool.

Non-operative management can be tried depending upon the stage of the pathology and severity of the symptoms but most patients usually require operative management.

From the review and comparison of different articles, it can be concluded that direct plantar plate repair, combined with Weil’s osteotomy and soft tissue release, gives the best results in terms of treatment of the tear, prevention of post-operative complications and patient satisfaction. With further work in this field in the future, newer techniques of repair can be devised with even better surgical results.

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today

 

Authors

Yogesh Joshi

Yogesh Joshi is a specialty doctor at the Foot and Ankle Unit of Wrexham Maelor Hospital. After graduating in India, he aspired to become an orthopaedic surgeon, came to the UK and completed his FRCS(Orth) in 2011. His interest is in minimally invasive orthopaedic surgeries in particular reference to the shoulder and knee joint.

Asad Syed

Asad Syed is a consultant at the Foot and Ankle Unit of Wrexham Maelor Hospital. He completed his training working at the famous Leeds Teaching Hospital ‘Jimmy’s’. While training he became interested in foot and ankle surgery, completing a one-year fellowship at Arrow Park Hospital on the Wirral. Prior to this he worked in many busy foot and ankle units in the UK.

Yasir Ali

Yasir Ali is a foundation trainee, at the Foot and Ankle Unit of Wrexham Maelor Hospital.

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