While there are a variety of potential etiologies with first metatarsophalangeal joint (MPJ) pain, these authors examine an alternative diagnosis of synovial plica syndrome in a 14-year-old patient without significant medical history or a triggering trauma.
First metatarsophalangeal joint (MPJ) pain is a common complaint addressed in the podiatric field. Vast etiologies for this concern include traumatic injury, overuse injury, degeneration, intra-articular injury, inflammatory arthropathies, various impingement syndromes, etc. One possible etiology of first MPJ pain that has not been described in podiatric literature is that derived from the plica complex located within the first MPJ anatomy.
In the orthopedic literature, researchers have described plicae as asymptomatic or symptomatic inward folds of synovial lining.1-7 Similarly, there are certain presentations of first MPJ pain that mimic synovial plica syndrome (SPS), which has been discussed in literature on the knee.2,6,7
In the following case report, we present the novel concept of first MPJ plicae and the characteristics of synovial plica syndrome (SPS) that may contribute to first MPJ pain.
When A 14-Year-Old Patient Presents With Recalcitrant First MPJ Pain
A 14-year-old Caucasian female without significant medical history other than a body mass index (BMI) of 23.49 presented to our clinic for a second opinion and potential surgical consult for first MPJ pain that had been present for over a year without known trigger or trauma.
The patient primarily characterized her pain as intermittent and sharp, localized to the first MPJ, and occurring with the propulsive phase of gait. She also related that sometimes this pain restricted her ability to fully dorsiflex the great toe. If the incidents of pain continued throughout the day, the discomfort would evolve to a consistent dull ache with associated mild edema by the end of the day. She is an active teenager who participates in softball and experienced limited movements with groundwork and fielding balls. The sensations of sharp pain had become more frequent over the prior year, causing the patient and her parents to consider surgical intervention.
Prior treatment by previous providers included the rest, ice, compression and elevation (RICE) protocol, non-steroidal anti-inflammatory drugs (NSAIDs), physical therapy and intra-articular injections. All of these modalities provided temporary benefits of edema control and improvement of the dull ache. However, the patient noted the sharp pain did not respond to these interventions.
During the clinical examination, we noted tenderness to palpation at the dorsolateral aspect of the first MPJ. With first MPJ range of motion, there was an intermittent “catching” sensation on dorsiflexion that prevented full motion in the sagittal plane. This impingement finding also reproduced the chief clinical symptom.
The patient’s joint range of motion was otherwise unrestricted with no crepitus. There was no instability of the collateral ligaments clinically although we noticed the patient was likely guarding during these movements. There was a mild dorsomedial prominence at the first metatarsal head without tenderness to palpation. There was also no tenderness to palpation of the rest of the first metatarsal head, hallux proximal phalanx or sesamoid apparatus.
Radiographic imaging was benign with no evidence of bony abnormalities nor signs of trauma in the clinical area of concern. From magnetic resonance imaging (MRI), the radiology report commented on mild reactive bone marrow edema at the lateral base of the proximal phalanx. Upon further review of the imaging, we noted a mild thickening of soft tissue with minimal increase in signal intensity evident at the dorsal aspect of the first MPJ.
With concerns for impingement-type symptoms resistant to anti-inflammatory treatment modalities, we decided to conduct an open arthrotomy of the first MPJ to address any soft tissue anomalies and evaluate for articular injury. The diagnosis preceding surgery included impingement of the first MTPJ and mild bunion deformity.
Intraoperatively, meticulous dissection of the first MPJ capsule demonstrated a dorsally thickened band of tissue (primarily hypertrophic when visualized from a lateral perspective, which obscured the view of the joint space (see first photo above). With joint manipulation, we could intraoperatively replicate impingement restrictions noted on the previous clinical examination during dorsiflexion. During this maneuver, the thickened band of capsular tissue became ensnared within the joint space, preventing full dorsiflexion. We observed this tissue to be an attached component of the joint capsule, often referred to as plica, located on the capsule’s inferior surface.
We excised the hypertrophied plica to reveal adjacent healthy-appearing capsule and pristine articular surfaces (see second photo above). Repeated motion of the joint after excising the hypertrophied capsular tissue demonstrated full and fluid range of motion without impingement of the joint. In addition to plica excision, we observed slight medial collateral ligament insufficiency intraoperatively, which we addressed with modest medial ligament plication.
Within the first week postoperatively, the patient began weightbearing in a postoperative shoe and conducting gentle, passive range of motion exercises. At four weeks post-op, we prescribed physical therapy with mandates for no closed-chain exercise until six weeks post-op and advancing exercise as tolerated. Subjectively, at four weeks postoperatively, the patient remarked on an absence of preoperative symptoms, commenting that she had unrestrained and pain-free joint range of motion. Additionally, she shared that any pain she experienced was more “superficial” around the incision rather than “deep” within the joint as perceived preoperatively. She returned to full activity and sport by six weeks postoperatively and had no recurrence of symptoms at her 12-month postoperative visit.
Where Does Synovial Plica Syndrome Fit In A First MPJ Differential Diagnosis?
As we mentioned previously, plicae are inward folds of capsular synovial tissue that we observed as thin, pliable linings extending from the synovial joint that may have intra- or extraarticular attachments.6 The elasticity of this tissue type permits for the tissue to change its shape when going through normal joint movements.6 In non-pathologic states in the knee, these folds of synovium are almost transparent when viewed via arthroscopy.4,6 This non-pathologic finding of thin, pliable, near transparent tissue makes the plica hard to distinguish from adjacent capsular tissue layers, which is most likely why plica is not commonly mentioned as a normal anatomic variant of the first MPJ.
Plicae are thought to become pathologic when there is an alteration in the pliability of synovial tissue, which generally stems from an inflammatory process.6 As described in knee literature, plica inflammation primarily results from a biomechanical injury such as trauma or repetitive mechanical irritation (i.e. overuse injuries).2,6,7 Gross anatomic changes accompanying pathologic plicae include fibrosis and thickened banding of the capsular tissue.1 Histologically, these changes are characterized by hypertrophy, progressive collagenization and hyalinization of the tissues.3,4
These histologic changes result in thickened synovial tissue located adjacent to a theoretically functioning joint, thus creating material that causes impingement within or bowstringing across the joint.2 It is a perpetual pathologic cycle as the dynamic derangement of the joint (via impingement or bowstringing) creates an inflammatory state. Subsequently, this environment perpetuates irritable hypertrophy of the synovial plica, which results in symptomatic plica joint pain, also referred to as synovial plica syndrome.2
Causes of soft tissue impingement specific to the first MPJ include any condition that causes intra-articular bleeding (hemarthrosis) or synovitis within the joint capsule. This provides an abundance of potential etiologies, ranging from internal (systemic or biomechanical such as osteoarthritis) to external (acute trauma) causes for potential impingement syndromes of the first MPJ.
As in this case study, synovial plica syndrome of the first MPJ exists primarily as a diagnosis of exclusion with principal characteristics of impingement symptoms or complaints of activity-exacerbated pain. In such cases witnessed by the senior author, typical pain is localized dorsal to the first MPJ with the potential for global joint line tenderness versus more isolated areas of symptomology (medial- versus central- versus lateral-predominant symptoms). This dorsal tenderness finding is in the area of the theorized first MPJ plicae (See third photo above).
In this particular case, the impingement of the plica restrained joint motion intermittently and intraoperatively became entrapped within the joint space upon repetitive motion, preventing full dorsiflexion motion with entrapment. In the knee literature, symptomatic plicae have analogous clinical presentations with tenderness on palpation of the plica area being a primary characteristic and common reports of “popping” or “snapping” sensations during knee flexion during which the plica bowstrings across bony surfaces.5,6
For this diagnosis, radiographic imaging is a tool one may employ to confirm an absence of osseous pathology but it does not assist in confirmation of synovial plica syndrome. This again is a diagnosis of exclusion, is soft tissue-based, and usually has no outstanding findings on magnetic resonance imaging (MRI) reads.1,2 With predominantly negative advanced imaging findings and exclusion of other pathologies of the first MPJ, one may consider a diagnosis of first MPJ impingement and subsequently synovial plica syndrome. Clinicians can only confirm the etiology with tissue analysis of impinged joint material or intraoperative identification of tissue impingement.2
Treatment for synovial plica syndrome in the knee and other joints generally focuses on early identification and physical therapy with primary attention to reduction of joint inflammation and underlying pathologies that contribute to inflammation (i.e. unstable biomechanics).1 Additionally, patients may benefit from intra-articular/ intralesional injections if not otherwise contraindicated. For those patients who have symptoms resistant to conservative measures, there has been relatively good success in total excision of symptomatic plicae from the joint capsule, whether it is via an open or arthroscopic approach.1
In the above case study, the plica we identified intraoperatively was grossly hypertrophic and impingement was evident on dorsiflexory manipulation of the joint. These intraoperative findings facilitated the identification of a straightforward nidus for the patient’s presenting symptoms. In a word of caution, distinction between normal and pathologic tissue, and discrimination of capsular layers can easily become problematic without meticulous dissection of the capsule intraoperatively. Therefore, in cases of undifferentiated first MPJ impingement-type symptoms in which suspicion for symptomatic plica exists, we advise an attentive operative approach to capsule dissection. In addition, Bellary and colleagues emphasize in toto excision of plica as remnants of pathologic plica tissue within the capsule have the potential to fibrose together, creating a recurrence of the condition.2
The intent of this case report is to provide an additional differential diagnosis for first MPJ impingement-type pain and discuss an anatomic variant relatively unreported in the podiatric literature. There is still much that is unknown regarding the plica complex as it relates to the first MPJ and future investigation is necessary to advance our understanding of diagnosing and treating symptomatic plicae.
Synovial plica syndrome is an impingement condition that is uncommon in the foot and exists as a diagnosis of exclusion. Nonetheless, one should consider synovial plica syndrome as a differential diagnosis for first MPJ pain with impingement-like presenting symptoms. Though one can potentially manage this condition with conservative treatment, surgical excision of plicae via meticulous dissection of capsular tissue is a viable option for symptoms recalcitrant to conventional anti-inflammatory targeted treatments.
Dr. Oloff is the Program Director of the Podiatric Residency Program at St. Mary’s Medical Center in San Francisco and an Attending Physician with the Palo Alto Medical Foundation in Burlingame, Calif.
Dr. Todd is an Attending Physician with the Palo Alto Medical Foundation in Burlingame, Calif.
Dr. Wilson is a third-year resident in the Podiatric Residency Program at St. Mary’s Medical Center in San Francisco.
1. Casadei K, Kiel J. Plica Syndrome. In: StatPearls [Internet]. Treasure Island, Fla: StatPearls Publishing;2019. Available at: https://www.ncbi.nlm.nih.gov/books/NBK535362/. Updated April 29, 2020. Accessed January 25, 2021.
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