Arthroscopy of the Great and Lesser Toes



Arthroscopy of the Great and Lesser Toes


RANDALL A. FARAC

RICHARD D. FERKEL



INTRODUCTION

Evaluating and treating the small joints of the foot, including the great toe, has traditionally been difficult, except by arthrotomy. With the advent of small-joint arthroscopes and instrumentation, arthroscopic indications and techniques of these small joints are expanding. Advancements in the understanding of the complex anatomy and biomechanics of the forefoot have allowed for greater realization of pathoanatomy amenable to arthroscopic treatment. Arthroscopically assisted reconstructive procedures for degenerative and inflammatory pathologies are becoming accepted alternative techniques for traditionally open procedures.

The use of the arthroscope in the great-toe metatarsophalangeal (MTP) joint was described originally by Watanabe and associates, who wrote about performing arthroscopy on 22 MTP joints as well as interphalangeal joints of the foot.1 Yovich and McIlwraith discussed the use of the arthroscope to debride osteochondral fractures in MTP joints of horses in 1986.2 Lundeen reported on 11 great-toe arthroscopies in the podiatry literature in 1987, but no results were reported.3 Bartlett described successful arthroscopic debridement of an osteochondritis dissecans lesion of the first metatarsal head.4 Ferkel and Van Buecken detailed the technique in the first large-scale series of cases.5


GROSS ANATOMY

The first MTP joint is a chondroloid joint and is a source of frequent pathology. The MTP joint of the great toe is composed of the metatarsal head and neck, the proximal phalanx, and the medial and lateral sesamoids. The sesamoid complex consists of two sesamoid bones, eight ligaments, and seven muscles6 (Figs. 16-1, 16-2 and 16-3). The sesamoid articulation with the first metatarsal head is in continuity with that of MTP articulation. Most of the capsuloligamentous stabilizing structures are concentrated on the plantar surface of the joint.

The dorsal surface of the MTP joint is dominated by the extensor hallucis longus tendon (EHL), which lies in the dorsal midline. The extensor hallucis brevis (EHB) tendon is just plantar and lateral to the EHL. The sagittal hood spreads out from the tendon sheath, encasing the ligaments to form a confluence of thickened capsular tissue extending plantarward to the collateral ligaments in the midline both medially and laterally. These capsuloligamentous structures align at the equator of the joint. These fan-like structures extend from the upper condylar region of the first metatarsal head to the base of the proximal phalanx.

A small bony ridge or crista separates the two sesamoid bones as they lie in their respective grooves (see Figs. 16-1 and 16-2A, B). A dense plantar pad covers the sesamoids and anchors them to the proximal phalanx. The medial sesamoid is ovoid and usually slightly more distal and larger than the lateral one. This allows visualization more easily via the arthroscope. The sesamoids are encased by two heads of the flexor hallucis brevis tendons (see Figs. 16-1 and 16-3A).

The capsuloligamentous complex of the MTP joint is the key factor contributing to its stability.7 Minimal stability is offered by the bony architecture of the joint and long flexor and extensor tendons. The adductor and abductor hallucis tendons provide some support to the lateral and medial capsule, respectively; the short flexor and extensor tendons blend into the capsule and give strong stabilizing elements (see Figs. 16-1 and 16-3A). The medial and lateral collateral ligaments provide strong support and have two components, the MTP and the metatarsosesamoid ligaments. The ligaments’ origins are on the medial or lateral border of the metatarsal head and fan out onto the proximal phalanx and plantar plate8 (see Fig. 16-3B). The arterial supply to the big toe is provided by the dorsal and plantar metatarsal arteries, branches of the dorsalis pedis artery (occasionally, the first plantar metatarsal artery is considered the terminal branch of the lateral plantar artery).7 The dorsal medial vein of the big toe joins the medial arm of the dorsal venous arcade and contributes to the formation of the greater saphenous vein9, 10 (Figs. 16-4 and 16-5A).

The superficial peroneal nerve provides much of the sensation to the great-toe MTP joint. It splits into a median, dorsal cutaneous branch above the ankle joint. This nerve then passes obliquely across the forefoot at the level of the first MTP joint to become the dorsomedial hallucal cutaneous nerve. It has consistently been found to lie as close as 2 to 5 mm plantar medial to the EHL. The medial plantar nerve appears between the abductor hallucis and the flexor digitorum brevis and gives off a proper digital nerve to the great toe and the three common digital nerves. This nerve innervates the medial and plantar aspect of the great toe. At the level of the MTP joint, it passes just plantar to

the collateral ligament. Sensation on the lateral side of the great toe is provided by the proper hallucal digital nerve, the terminal branch of the deep peroneal nerve, and lies beneath the transverse metatarsal ligament (see Figs. 16-4 and 16-5B). Due to the variation of deep and cutaneous nerves about the great toe and MTP, caution is advised when attempting to make any of the standard arthroscopic portals—blunt dissection technique is preferred.






FIGURE 16-1. Superolateral view of the bone-ligament-capsular anatomy of the MTP joint. (Illustration by Susan Brust.)






FIGURE 16-2. Sesamoid position. (A) Plane of cross section to study the sesamoids. (B) Cross-sectional anatomy of the metatarsal head with the medial and lateral sesamoids separated by a small bony ridge or crista. (Illustration by Susan Brust.)






FIGURE 16-3. (A) Plantar view of the MTP joint with the surrounding muscles and tendons. (B) Medial view of the first MTP joint and surrounding anatomy, including the sagittal hood and the medial collateral ligament.

The dorsomedial aspect of the first MTP joint has a reproducible synovial fold that invaginates an average of
7 mm into the joint. It has been hypothesized that this fold, composed of loose connective tissue and nerve endings, serves to increase joint congruity and stability. It can also tear and be a source of pain.11






FIGURE 16-4. Plantar view of the neurovascular supply of the great toe. (Illustration by Susan Brust.)






FIGURE 16-5. Dorsal view of the neurovascular supply of the great toe. (A) Deep dissection. (B) Superficial dissection. (Illustration by Susan Brust.)


BIOMECHANICS

The great-toe MTP joint is a stabilizer during the stance phase of gait. The great toe supports more than twice the load of the lesser toes, with the maximum force reaching 40% to 60% of body weight in normal walking.12, 13, 14 During running and jumping, these forces are increased proportionately.15 The instant center of motion for the first MTP joint falls within the first metatarsal head.13 With range of motion of the MTP joint, a gliding motion occurs at the joint surface.


PATIENT EVALUATION

Patients with great-toe MTP problems usually present with forefoot pain localized to the capsule and surrounding structures. A thorough history including the periodicity and aggravating factors for pain is paramount. Previous surgeries and treatment modalities, including shoewear, with temporal relationships for partial or complete relief of pain are noted. The level of activity for patients with great-toe MTP pain is vast and will dictate relevant pathology and
surgical expectations. Past medical or familial history of inflammatory arthritides or crystalline arthropathies should be investigated with appropriate laboratory studies.16

Physical examination includes evaluation of gait, bony and soft tissue deformity, active and passive range of motion, neurologic and vascular status, palpation of tender points, and pertinent provocative tests. Standard AP and lateral weight-bearing forefoot radiographs are obtained with axial sesamoid views if indicated. Osteophytes, loose bodies, joint space narrowing, deformity, generalized osteopenia, and cyst formation can usually be identified on plain radiographs. Evaluation of the sesamoids occasionally warrants computed tomography to assess this complex articulation, especially bipartite sesamoid pathology or complex deformity. MRI is useful for evaluating the soft tissues of the MTP joint, cartilage defects, bone edema, and the surrounding tendons.


INDICATIONS FOR ARTHROSCOPY

The diagnostic indications for arthroscopy of the great-toe MTP joint include persistent pain, swelling, stiffness, locking, or grinding symptoms despite conservative treatment. The therapeutic indications include:






FIGURE 16-6. Dorsal view of great-toe portals. (A) Note the position of the dorsomedial (1), dorsolateral (2), toe web (3), medial (4), and proximal medial (5) portals. These portals must be made carefully to avoid injuring the surrounding neurovascular structures. (B) Dorsomedial, dorsolateral, and toe web portals separated by the EHL tendon, with the toe suspended from a sterile device. (Illustration by Susan Brust.)


1. Synovitis and chondromalacia

2. Dorsal impingement in hallux rigidus, type 1 and 2

3. Osteochondral lesions of the metatarsal head and phalanx

4. Loose bodies

5. Arthrofibrosis

6. Gout

7. Sesamoidectomy

8. Bunionectomy with medial capsule imbrication

9. Arthrodesis

10. Infection

The contraindications include the presence of overlying soft tissue infection, advanced degenerative joint disease, severe edema, or poor vascular status.


PORTALS

Three portals are commonly used in arthroscopy of the great-toe MTP joint: dorsomedial (DM), dorsolateral (DL), and medial (M) (Figs. 16-6A, B, 16-7, and 16-8A, B). The dorsomedial portal is placed just medial to the EHL at or slightly distal to the joint line. Care must be taken when
establishing this portal to avoid injury to the medial dorsal cutaneous branch of the superficial peroneal nerve. The dorsolateral portal is placed just lateral to the EHL at or just distal to the joint line. Because the proper digital nerve lies beneath the transverse metatarsal ligament, the nerve is usually not in danger with the placement of this portal. The medial portal is placed through the medial capsule, midway between the dorsal and plantar aspects of the joint. It is usually established under direct vision because of the narrowness of the space in which it lies. In addition, extreme caution must be taken to avoid injury to the surrounding neurovascular structures.






FIGURE 16-7. Medial oblique view of great-toe portals. Note again the position of the dorsomedial (1), dorsolateral (2), toe web (3) medial (4), and proximal medial (5) portals. (Illustration by Susan Brust.)

Accessory working portals have been described for specific procedures (Figs. 16-6A, B, 16-7, and 16-8A, B):


1. Proximal medial portal: debridement of dorsal osteophytes

2. Plantar portal: lies in between the sesamoids and is best made with outside-in needle localization

3. Plantar medial portal: 4 cm proximal to the MTP joint

4. Toe web space lateral portal: to approach the lateral sesamoid


INSTRUMENTATION

Because of the small size of the great-toe MTP joint, small instrumentation is mandatory. Short 2.7-mm 30° and 70° arthroscopes or a 1.9-mm 30° arthroscope is used. An interchangeable cannula system is used so that the arthroscope and shaver can be shifted from one portal to another without repeated punctures into the capsule (Fig. 16-9). To prevent injury to the articular surface or the arthroscope, a small, lightweight chip camera (videoscope) is preferred. The light source is the same as for standard arthroscopic procedures, but a smaller light cord may be
necessary. Because of the size of this cord, breakage is easier, and replacement cords must be available at the time of surgery.

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Sep 25, 2018 | Posted by in RHEUMATOLOGY | Comments Off on Arthroscopy of the Great and Lesser Toes
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