How To Handle Second MTPJ Stress Syndrome

   Second MTPJ stress syndrome has become a catch-all term for patients who complain of chronic pain involving the second MTPJ. While it is important to differentiate this entity from a neuroma, intermetatarsal bursitis or a stress fracture of a metatarsal, it is even more important for the practitioner to determine an accurate etiology or etiologies for the second MTPJ stress syndrome. Only by understanding the cause of the problem can one develop an effective treatment plan.    When a patient has second MTPJ stress syndrome, he or she may have the following typical signs and symptoms:    • pain with pressure to the second MTPJ;    • a positive modified Lachman’s test (manual subluxation of the MTPJ that creates pain);    • pain in the sub-second metatarsal head with standing and/or ambulation;    • pain with the second MTPJ area that is well localized;    • edema of the second MTPJ area;    • painful second hammertoe (flexible or rigid depending on the amount of time since the onset of symptoms);    • possible dorsal dislocation of the second digit at the MTPJ;    • possible adduction (splaying) of the second digit when the foot is loaded;    • possible hyperkeratotic lesion of the sub-second metatarsal head;    • hallux abductus with bunion deformity, which may be symptomatic; and/or    • a hypermobile first ray with abnormal pronation.    The longer the problem has been present, the more digital deformity one will usually see. Possible etiologies of second MTPJ stress syndrome include:    • chronic overload of the second MTPJ which may be due to hypermobility of the first ray, longstanding hallux abductus with bunion deformity, negative metatarsal protrusion distance or chronic digital deformity;    • inflammatory disease affecting the second MTPJ;    • multiple steroid injections into the second MTPJ as a treatment for MTPJ stress syndrome; and/or    • a traumatic event affecting the second MTPJ.

What You Should Consider In The Diagnostic Workup

   Anatomical considerations for second MTPJ stress syndrome include rupture of the plantar plate, rupture of the MTPJ ligaments or a combination of the two ruptures. Other considerations include an abnormally long second metatarsal or an iatrogenic short first metatarsal.    In evaluating a patient with a painful second MTPJ area, one should initially rule out other possibilities for pain in that area. For example, while a neuroma in the second interspace can occur, it is certainly a rarity. Injecting a local anesthetic into the second interspace should be able to provide insight as to whether the symptoms are the result of nerve entrapment. However, in most cases, the pain is so well localized to the second MTPJ without distal paresthesias that one should be able to rule out a nerve problem just by clinical examination.    Obtaining X-rays of the involved area will rule out the possibility of a metatarsal stress fracture. The X-rays will also reveal whether there is a short first metatarsal (perhaps from a prior surgery), a long second metatarsal or the signs of a hypermobile first ray.    The X-rays will also provide knowledge of the condition of the second MTPJ. In some cases, I have injected the second MTPJ with local anesthesia and a radioopaque dye. This allows clinicians to determine in an acute condition whether there is an acute rupture of the plantar plate/capsule. If the symptoms resolve for the duration of the anesthetic, then the pathology is intraarticular. In some rare cases, I have ordered a MRI to evaluate the plantar capsule/plate structure but this has not proven to be very beneficial. One may also attempt to utilize ultrasound but, in my experience, I have not been able to utilize the result any more effectively than what I had gained from my clinical examination.

Key Pearls On Conservative Care

   Once you have determined that the problem is a second MTPJ stress syndrome, proceed to develop a logical treatment plan. Failure to adequately treat this condition most likely will result in the following sequella over a period of time. These sequella may include:    • a progression of symptoms;    • development or progression of a digital deformity that may include a lack of digital toe purchase, transverse plane pathology, rigidity of the deformity, dorsal dislocation of the second MTPJ, adjacent digital pathology; and/or    • arthrosis of the second MTPJ.    When it comes to patients who have not had the symptoms for very long and do not have any apparent digital or structural pathology (pre-dislocation syndrome), I will attempt conservative therapy. Of course, the modalities one employs depend upon the patient, his or her past medical history, the patient’s occupation, body weight, biomechanical findings and presenting symptoms.    In my experience, I have found that having the patients wear a removable Darco™ digital splint at night for four to six weeks keeps the digit plantarflexed and takes any tension off the plantar plate/capsule structure. Other conservative modalities for this condition include a Budin-type splint, which should be worn with shoes during the day, NSAIDs, contrast soaks, orthoses and/or a low profile synthetic walker, which should be worn for four to six weeks. One should also have the patient avoid certain activities such as running or aerobic exercise.    In many acute cases, employing one or more of the above modalities has proven to be very effective in resolving the symptoms and halting any further progression of symptoms or deformity. However, if the etiology is one of structure and an adjacent bunion deformity — and not a soft tissue or biomechanical condition — conservative modalities will usually eliminate acute symptoms but will not halt the progression of a digital deformity and future symptoms. One should explain this to the patient, emphasizing that correction of the underlying structural or adjacent first ray pathology is necessary to ensure a long-term favorable prognosis.    When patients do not respond to conservative therapy or have an etiology that requires surgical intervention, I and other members of the Department of Podiatric Surgery at the California School of Podiatric Medicine utilize the following surgical options depending upon the patient’s pathology.

When A Patient Has A Dislocated Second MTPJ And PIPJ Contracture

   If a patient has a dislocated MTPJ with contracture of the proximal interphalangeal joint (PIPJ), we may perform an open second MTPJ arthrotomy. This procedure enables us to excise inflammatory tissue, inspect the joint for cartilage damage, release soft tissue and free the plantar plate, depending upon the severity of the MTPJ dislocation.    One may perform an arthroplasty of the PIPJ – or fusion if the digit is abnormally long or if the PIPJ contracture is semi-rigid or rigid – along with a flexor tendon transfer and Kirschner wire stabilization. I normally utilize the flexor brevis tendon for a second digit, which allows one to maintain the flexor longus and preserve its action on the DIPJ.    If the digit is of normal length and the PIPJ contracture is reducible, clinicians may utilize an open arthrotomy of the PIPJ along with a flexor brevis tendon transfer.    If there is significant redundant tissue once the digit is realigned on the sagittal plane, one may perform a plantar skin plasty, which enables you to remove an ellipse of plantar tissue from the sulcus of the second digit. This procedure also helps to maintain digital ground purchase.

When There Is An Abnormally Long Second Metatarsal Or An Iatrogenic Short First Metatarsal

   When patients have an abnormally elongated second metatarsal or iatrogenic short first metatarsal, one may consider performing a Weil osteotomy, which allows shortening of the metatarsal but maintains its ability to bear weight.    Surgeons may also consider a digital procedure, whether it is a PIPJ arthroplasty, fusion or arthrotomy with flexor brevis tendon transfer. This procedure is necessary in order to negate the loss of physiological tension of the plantar fascia slip to the second digit that occurs with any shortening metatarsal osteotomy. Failure to perform the digital procedure will most likely result in a floating second toe within a certain time period postoperatively.    If there is significant redundant tissue once the digit is realigned on the sagittal plane, one may perform a plantar skin plasty, which enables clinicians to remove an ellipse of plantar tissue from the sulcus of the second digit.

How To Address Arthrosis Of The Second MTPJ

   If a patient has arthrosis of the second MTPJ, one may perform a partial metatarsal head resection with or without a lesser metatarsal joint prosthesis. Clinicians may perform the aforementioned digital procedure depending upon the pathology within the digit. One may also opt for a plantar skin plasty if there is redundant skin once the digit is realigned on the sagittal plane.

When There Is Adjacent Digital Pathology

   In regard to patients who have adjacent digital pathology, one should correct any bunion deformity in which the hallux is abutting the second digit even if the bunion is asymptomatic. Surgeons should also correct any medial transverse plane malalignment of the third digit.    I did not include repair of the plantar plate in the above discussion but, in my experience, though limited, the aforementioned procedures were just as effective without the plantar dissection.

A Few Thoughts On Postoperative Management

   Postoperative management will depend upon the procedures that clinicians perform. When one employs a Kirschner wire for stabilization, maintain it for at least three weeks or longer if possible to allow for sufficient fibrosis and tendon healing within the digit. Using AirCast™, a low-profile synthetic walker, has been proven to be an excellent way to allow the patient to remain ambulatory while eliminating the propulsive phase of gait and offloading the forefoot.    I will also have the patient utilize the removable digital splint for six to eight weeks at night following the removal of all bandages and Kirschner wire. For a period of two months after surgery, I advise the patient to refrain from engaging in certain activities (such as walking up hills, walking on wet sand, squatting to perform gardening, etc.) that will create extreme dorsiflexion of the second MTPJ.

Final Notes

   Second MTPJ stress syndrome is a common podiatric problem. Practitioners must be able to differentiate it from several other entities with similar symptoms and then develop a logical treatment plan based upon the underlying pathology or pathologies they identify. In summary, one should:    • identify the underlying etiology or etiologies;    • attempt conservative therapy in patients with a stable second MTPJ (acute);    • perform a flexor tendon transfer whenever one performs a shortening osteotomy on the second metatarsal;    • correct adjacent digital and/or metatarsal pathology;    • perform a plantar skin plasty if tissue appears redundant once the second digit has been realigned;    • utilize a Kirschner wire to help stabilize the second digit during the healing process;    • utilize a removable digital splint after removing bandages and Kirschner wire; and/or    • educate the patient regarding the avoidance of certain postoperative activities for several months. Dr. Gerbert is the Director of Continuing Medical Education and is a Professor in the Department of Podiatric Surgery at the California School of Podiatric Medicine at Samuel Merritt College. He is the Chief of Podiatric Surgery at St. Mary’s Medical Center in San Francisco and is a Fellow of the American College of Foot and Ankle Surgeons.
 

References:

1. Coughlin M. Second metatarsophalangeal joint instability in the athlete. Foot and Ankle 1993, 14:309.
2. Jenkin WM. Approach to the Patient with Ankle and Foot Pain. In: Imboden JB, Hellman DB and Stone JH, editors. Current Rheumatology Diagnosis and Treatment, Lange Medical Books 2004. Chapter 7 pp. 63-64.
3. Jenkin WM. Central Metatarsophalangeal Joint Arthrosis: Evaluation and Surgical Management. In: Oloff LM, editor. Musculoskeletal Disorders of the Lower Extremities. WB Saunders Company 1994. Chapter 29, pp. 481-495.