Lateral elbow painful snap secondary to a continuous plica synovialis in the radiocapitellar joint: Case report

Abstract

Lateral elbow painful snapping is a rare, debilitating condition, often misdiagnosed for lateral epicondylitis due to its unfamiliarity or lack of definitive imaging tool to diagnose it. We report a case of a 25-year-old male with a 4-month history of painful snapping during terminal elbow flexion, triggered by weightlifting and push-ups, without prior trauma. Clinical examination showed bilateral elbow hyperextension of 10°, with visible/palpable snapping and pain at 110°-120° flexion, occurring in both supinated and pronated forearm positions, only when initiated from full extension. MRI revealed a small triangular soft tissue fold with effusion in the radio-capitellar joint. Arthroscopy identified a thick, whitish, continuous band of soft tissue spanning the radio-capitellar joint from anterior to posterior, with a free inner end and lateral capsular attachment. Cartilage erosions were noted on the proximal and outer radial head (contiguous portion). Arthroscopic resection of the interposing tissue resolved symptoms immediately post-operatively. Histopathology confirmed features consistent with a synovial plica. Literature suggests that the dynamic nature of this condition and clinicians' unfamiliarity often lead to missed diagnoses on plain MRI. Unlike the commonly reported posterolateral plica, this case involved a rare continuous band causing snapping in both pronated and supinated positions. This report underscores the importance of recognizing atypical presentations of lateral elbow snapping and highlights the efficacy of early arthroscopic excision for symptom relief and cartilage preservation, offering a valuable diagnostic and therapeutic approach for this rare condition.

Highlights

• •Snap reproducible only when flexion is initiated from full extension and patient may not have any history of direct injury to the elbow preceding the onset of symptoms. Generalized laxity with hyperextension of elbow joint (like in our case) must be elicited clinically.
• •Differentials for lateral elbow painful snapping to be kept in mind for better clinical correlation and imaging interpretation, however definitive diagnosis with true nature of the tissue can only be confirmed surgically and by histopathologic evaluation.
• •The morphology of the continuous band of hypertrophied plica may have a bearing on the clinical presentation of snap occurring during terminal flexion in both pronation and supination.
• •Early excision prevents cartilage erosions with arthroscopy allowing better visualization and early post-operative mobilization prevents further cartilage wear.

Introduction

Painful snapping of the lateral elbow, though rare, can be debilitating and presents a diagnostic challenge. Its uncommon presentation often leads to misdiagnosis, with the condition frequently mistaken for more common disorders such as lateral epicondylitis [1]. The literature attributes this condition to extra- or intra-articular etiologies, including loose bodies, hypertrophic plica, a loose annular ligament, or an aberrant meniscal tissue interposing within the radio-capitellar joint, causing mechanical impingement [[1], [2], [3], [4]]. These etiologies represent either pathological entities or pathological changes in normally occurring tissues in the elbow joint, which slide in and out of the joint during specific motions, producing the characteristic snap. Clinically, identifying the snap is only the first step, as routine imaging modalities often fail to diagnose this dynamic condition on their static images. We report a case of lateral elbow painful snapping caused by a hypertrophied plica synovialis, discussing its underlying mechanism, diagnostic approach, impact on articular cartilage, treatment via arthroscopic excision, histological confirmation, and clinical outcome.

The case

Medical history and clinical description and imaging

A 25-year-old man presented with a four-months history of snapping in the lateral aspect of his left (non-dominant) elbow. The snap was painless for the initial two weeks which became painful later. The snap occurred during terminal flexion on lifting weights [dumbbells or barbells (>5 kg)] or on loading the elbow (push-ups), both when the motion was initiated from maximum extension of the elbow joint. The symptoms persisted despite a trial of conservative treatment with immobilization and analgesics. The patient reported no symptoms while performing similar activities on the right (unaffected) side and no history of trauma preceding symptom onset. Clinically, the patient exhibited 10° of hyperextension in both elbows, with no evidence of generalized joint laxity (Beighton score: 2/9). Tenderness was noted on palpating the radio-capitellar joint, accompanied by visible and palpable snap with pain between 110° and 120° of elbow flexion (with unrestricted full flexion) when moving from full extension (−10°) with the forearm in supination and pronation. This finding was reproducible passively. Plain radiographs appeared normal, while MRI revealed joint effusion and a small triangular soft tissue fold (hypointense on T1 and T2 sequences) interposed in the radio-capitellar joint.

Intervention (intra-operative/arthroscopic findings) and outcome

Diagnostic arthroscopy by standard 4 mm, 30-degree angled arthroscope with pump through proximal-anteromedial and posterolateral portal revealed a thick, white meniscus-like tissue with free inner end and peripherally continuously blended with the joint capsule (Fig. 1). The interposing soft tissue was occupying the anterior, lateral and posterior aspect of the joint space with cartilage erosions seen in the proximal rim of the radial head; regions that are contiguous with the tissue. Minimal synovitis adjacent to the tissue was seen. After collecting tissue samples for biopsy (Fig. 2), the interposing soft tissue was resected from its peripheral attachment with part of joint capsule using an arthroscopic shaver and RF ablator (Fig. 3). The lateral elbow snap that was present post anaesthesia, disappeared immediately after tissue resection. Immediate mobilization of elbow joint was initiated and by 2 weeks post-operative, patient regained full ROM with no pain and snapping.

Fig. 1.

(A-C) Arthroscopic view of radiocapitellar joint through proximal anteromedial portal showing white, thick continuous band of hypertrophied plica (extent denoted by arrows) and cartilage erosion in the contiguous part of radial head (denoted by star); ‘C’- capitellum, ‘RH’- radial head, ‘P’- Hypertrophied Plica.

Fig. 2.

(A) Biopsy of plica tissue taken using punch forceps, also showing marginal synovitis (B) plica excision using arthroscopic shaver and (C) arthroscopic radiofrequency ablator, (D) post excision of hypertrophied plica showing contiguous zone of cartilage erosion on proximal outer rim of radial head (denoted by star); ‘C’- capitellum, ‘RH’- radial head.

Fig. 3.

(A) Arthroscopic view from the posterolateral portal showing plica interposing between the radial head and capitellum, (B) radiocapitellar joint space visible post excision of the plica.

Histopathological findings

The section showed bundles of fibro-collagen and layer of synovial tissue in the border with blood vessels, conclusive of a synovial plica (Fig. 4).

Fig. 4.

Histopathology reveals dense bundles of fibro-collagen tissue and scattered spindle-shaped fibroblasts and layer of synovial tissue in the border with blood vessels, conclusive of a synovial plica.

Discussion

Though lateral elbow pain is a common complaint in orthopedic practice, its association with snapping is frequently overlooked or underdiagnosed [1]. Clinically, pain in this condition is typically localized distal to the lateral epicondyle, along the radiocapitellar joint line, and is associated with a characteristic snap during specific joint motions, which patients often reproduces when asked. Routine preoperative plain MRI may frequently misdiagnose this dynamic condition due to its static imaging. In contrast, dynamic ultrasonography and contrast arthrography have been reported to be of some help. [5,6]. However, the true nature of the tissue causing the symptoms can only be confirmed when explored surgically to know its morphology, location, extent, continuity with surrounding structures and ideally, when followed by a histopathologic examination of the resected tissue.

One among the handful of reported differentials for this condition include a pathological annular ligament- which may be a torn ligament with its detached portion interposing in the joint or become hypertrophied, that slips in and out of the joint in extension-flexion [7]. Additionally, an unstable or an incompetent annular ligament may produce similar symptom due to the resultant instability instead of impingement [3]. Other differential could be the presence of a synovial plica (variably termed as plica syndrome, elbow synovial fold syndrome, or synovial fringe), which is an embryonic relic of the synovial fold, that may get inflamed and/or hypertrophied due to repeated trauma producing symptoms [8]. Bozentka (2000) reported that the snap due to an annular ligament pathology manifest not only during elbow flexion-extension, but also during pronation and supination (unlike plica), which perhaps, may be the only way to differentiate them clinically [9]. However, the final diagnosis can only be confirmed on surgical evaluation where a hypertrophied plica appears like a whitish band of soft tissue fold, earlier reported to be ‘meniscus like’ in appearance. Duparc (2000) clarified that only a histopathologic presence of fibrocartilage can qualify a tissue to be considered a true meniscus [10] and by far only 3 cases has been reported in literature, two in adults producing snap and one in a 15-year-old child causing extension lag [4,6,11]. A synovial plica instead, is a fold containing fibrocollagen and adipose tissue (occasionally showing chondroid metaplasia) with layer of synovial tissue in the borders and is more commonly seen in larger joints than in the elbow. The location and extent of the synovial plica have been classified into five regions (anterior to posterior) based on their relation to the superior edge of the annular ligament [10], with the posterolateral region being the most common site [1]. An anatomic study by Isogai (2001) on cadaveric elbows from 179 adults and 40 embryos categorized plicas into anterior and posterior folds. In rare instances, a complete circular fold may occur, as observed in our case [12]. The presence of a hypertrophied plica impinging in the radiocapitellar joint on MRI, combined with the clinical and radiological absence of other differential diagnoses, helped narrow the cause of painful lateral elbow snapping preoperatively. We hypothesize that the morphology and location of the plica may influence clinical presentation, like in our case, a continuous band of plica produced snapping during terminal flexion in both pronated and supinated forearm, challenging the common assumption that flexion-pronation is the provocative maneuver for preoperative diagnosis. [13].

Other than the mechanical impingement, plica is also reported to cause chondral erosions of the radial head, described as a “kissing lesion” in the earliest report by Clarke, who assumed the snapping was due to loose bodies in the joint [14]. Antuna and O'Driscoll (2001) reported 14 patients with hypertrophied plica, 13 of which exhibiting radial head chondromalacia [13]. As hypothesized by Steinert (2018) that the degree of chondromalacia may correlate with delays in surgical intervention [2], emphasizing the importance of early diagnosis and prompt treatment of snapping elbow is critical, as the interposing tissue can damage cartilage through either contact abrasion (as in our case) or abnormal articulation due to an unstable or lax annular ligament. Excision, whether open or arthroscopic, yields favorable outcomes. Arthroscopic evaluation additionally offers complete visualization of the joint surface, facilitating precise identification, isolation, and excision of the tissue across all quadrants of the radial head. Furthermore, it allows early mobilization to prevent postoperative stiffness.

Conclusion

A case of painful snapping of the lateral elbow should be approached with meticulous clinical evaluation of the elbow's range of motion, snap position, and pain location, as these signs are pivotal in diagnosing the cause for snap. One should consider differential diagnoses, particularly soft tissue interposition in the radiocapitellar joint, during the examination. In our case, we hypothesize that the hyperextension of the elbow likely contributed to plica hypertrophy through repetitive loading, with the snap reproducible only during flexion from maximum extension and in both pronation and supination, suggesting a near-circumferential plica, at the hindsight. Magnetic resonance imaging (MRI) aids diagnosis but is limited by its static nature, often failing to fully capture this dynamic condition and requiring surgical exploration and histopathological confirmation to determine the true tissue nature. Prompt excision is essential to prevent articular cartilage damage, with arthroscopic debridement offering excellent visualization, precise excision, and early mobilization, leading to favorable functional outcomes. This case report highlights the importance of a targeted clinical approach, cautious interpretation of imaging, and timely surgical intervention to achieve optimal recovery in patients with lateral elbow snapping caused by a hypertrophied plica synovialis.

CRediT authorship contribution statement

Darshan Kumar A. Jain: Writing – review & editing, Methodology, Data curation, Conceptualization. Harshit Bhaskar Shetty: Writing – original draft.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.