Arthroscopic Interpositional Arthroplasty of the Second Metatarsophalangeal Joint

Small Joint Arthroscopy of the Foot

Recently, there have been new advances in the arthroscopic approach to small joints of the foot. This is directly related to the improvement of surgical equipment, new techniques, and publications. These improvements led to broadening indications as well as minimizing complications. Several articles recently presented the uses of arthroscopic surgery in the small joints of the foot; however, the use is still relatively limited. Arthroscopic evaluation of the small joints of the foot includes the first metatarsophalangeal, lesser metatarsophalangeal, tarsometatarsal, talonavicular, and calcaneocuboid joints as well as the interphalangeal joint to the great toe and lesser toes.

A new lesser metatarsophalangeal joint replacement arthroplasty design - in vitro and cadaver studies

Background

Isolated degenerative joint disease and/or Freiberg’s infraction of the lesser metatarsophalangeal joint, although not frequent may become debilitating in the younger individual. Currently, once conservative management fails, the mainstay of treatment is debridement and excision-interposition arthroplasty. Replacement arthroplasty has been ineffective in the long term as the joints are subject to severe repetitive fatigue loading over small articulating surfaces through a wide range of motion. This is an in vitro and cadaver study of a new design replacement arthroplasty developed by the senior author.

The aim of this study is to evaluate this novel replacement arthroplasty of the lesser metatarsophalangeal joint in a laboratory setting and cadaver implantation.

Methods

This three-component mobile bearing device is made of titanium and high density polyethylene which evolved over 4 years. It was subjected to 5,000,000 cycles in a laboratory under physiological and excessive forces to assess resistance to fatigue failure and wear pattern of the polyethylene liner. Following these tests, it was implanted in 15 fresh frozen cadavers at various stages of its development, during which the surgical technique was perfected. Range of motion and stability was tested using custom made instrumentation in four cadavers. The implant was inserted in a further two cadavers by an independent foot and ankle surgeon to check reproducibility.

Results

The device showed almost no signs of wear or surface deformation under physiological forces. The surgical technique was found to be simple and reproducible in the cadaver trial.

The average dorsiflexion was 28.5° and 28.9° pre- and post-implant respectively. The average plantar flexion was 33.8° and 20.8° pre- and post- implant respectively. The joints were stable both pre- and post-operatively. Post-operative stability was objectively assessed for dorsal displacement and dorsiflexion using a 5 kgf (49 N) and was found to be excellent.

Conclusion

This novel lesser metatarsophalangeal joint replacement arthroplasty has been developed as an option in the surgical treatment of symptomatic degenerative joint disease and/or Freiberg’s infraction resistant to conservative treatment. The implant was found to be durable and resistant to wear in the laboratory testing. The cadaver studies have shown it to require minimal specialized instrumentation with good surgical reproducibility.

This proof of concept study is the basis for clinical trials.

Interpositional Arthroplasty With Extensor Digitorum Brevis Tendon in Freiberg Disease

BACKGROUND

No consensus has been reached in the treatment of Frieberg disease. Our aim was to evaluate medium- to long-term results of patients with advanced Freiberg disease managed with extensor digitorum brevis tendon interpositional arthroplasty.

METHODS

There were 24 patients (19 females, 5 males) managed with interpositional arthroplasty for advanced Freiberg disease between 2003 and 2015. The mean follow-up was 133.8 (range, 60-198) months. According to Smillie classification, there were 4 grade 3, 13 grade 4, and 7 grade 5 patients. Patients were evaluated preoperatively and at the final follow-up with the American Orthopaedic Foot & Ankle Society (AOFAS) score and metatarsophalangeal joint range of motion and postoperatively with visual analog scale (VAS) and subjective satisfaction evaluation. Joint space was evaluated on x-rays.

RESULTS

Mean AOFAS score increased (53.9 to 80.3, P = .001). Eight patients had excellent, 14 had good, and 2 had fair scores. A significant increase was found in dorsiflexion (38.1° [24°-52°] vs 55.3° [34°-65°]; P = .001) and plantarflexion (19.0° [10°-28°] vs 28.6° [19°-39°]; P = .001). Narrowing of the joint space was not seen in any patient, but expansion was determined in all patients (0.39 [0.35-0.47] vs 0.44 [0.41-0.47] cm; P = .002). Of the patients, 9 were very satisfied, 12 were satisfied, 2 were moderately satisfied, and 1 was dissatisfied. The mean postoperative VAS pain score was 1.7 ± 0.9 (0-4).

CONCLUSION

After a minimum 5-year follow-up, most patients with Freiberg disease managed with interpositional arthroplasty using the extensor digitorum brevis tendon had excellent to good functional results with a widening of the joint space.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

The use of polyvinyl alcohol hydrogel implants in the lesser metatarsal heads. Is it safely doable? A cadaveric study

BACKGROUND

The use of synthetic polyvinyl alcohol hydrogel (PVAH) implants for treatment of lesser toe metatarsophalangeal joint (MTPJ) arthritis is promising and currently limited by the size of implants available. The primary objective of this cadaveric study was to investigate the maximum drilling size and largest PVAH implant dimension that could be safely introduced while still preserving an intact bone rim of the lesser metatarsal heads.

METHODS

Height and width of all lesser metatarsals were measured on CT and during anatomic dissection. Sequential reaming of the second to fourth metatarsals was performed. Maximum reaming size, largest implant inserted, and failure of the metatarsal head were recorded. Metatarsal head sizes were compared and a multiple regression analysis evaluated measurements that influenced maximum drilling and implant size.

RESULTS

CT and anatomical measurements demonstrated significant correlation (ICC range, 0.-0.85). Mean values for height and width of the metatarsal heads were respectively: second (14.9 mm and 9.9 mm), third (14.8 mm and 8.8 mm), fourth (14.0 mm and 8.7 mm) and fifth (12.3 mm and 9.3 mm). All the second, third and fourth metatarsal heads could be safely drilled up to 7.5 mm, preserving an intact bone rim. At 80% of the time, the heads could be safely drilled up to 8.0 mm. Height of the metatarsal heads was the only factor to significantly influence the size of maximum reaming and implant introduced. In respectively 20%, 40% and 50% of the second, third, and fourth metatarsal heads, neither 8 mm nor 10 mm PVAH implants could be used.

CONCLUSIONS

Our cadaveric study found that the even though the majority of the lesser metatarsal heads could be safely drilled up to 8 mm, the smallest PVAH implant size currently available in most countries (8 mm) could be inserted in most of the second, but only in about half of the third and fourth metatarsal heads. The remaining bone rim around inserted implants was considerably thin, usually measuring less than 1 mm. In order to optimize the use PVAH in lesser metatarsal heads, smaller implant options are needed.

Arthroscopic Dorsal Closing-Wedge Osteotomy of Metatarsal Head for Management of Freiberg Infraction

Freiberg infraction is a relatively rare osteochondrosis of the lesser metatarsal head. Operative treatment is indicated if conservative treatment fails to relieve the pain. Dorsal closing-wedge osteotomy is a realignment osteotomy of the metatarsal head and neck to redirect the articular surface, allowing the intact plantar cartilage to articulate with the proximal phalanx. The purpose of this technical note is to describe the details of arthroscopic dorsal closing-wedge osteotomy of the metatarsal head for management of Freiberg infraction. Although dorsal closing-wedge osteotomy has been proposed for the treatment of late-stage Freiberg infraction, we reserve this technique for early stages of the disease.

Treatment of Freiberg Disease

Freiberg disease, or osteochondrosis of the lesser metatarsal head, usually involves the second metatarsal and presents during the second or third decades of life. Conservative measures to relieve pressure on the affected metatarsal head are the first-line treatments, with good success for Smillie stage I to III disease. Operative treatments are divided into joint-preserving and joint-reconstructing procedures. Although multiple case series describe success with numerous techniques, there are no established guidelines for treatment. All surgical techniques carry a risk of a stiff or floating toe and transfer metatarsalgia. This article reviews the current surgical treatment options for Freiberg disease.