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Year : 2016  |  Volume : 16  |  Issue : 1  |  Page : 79-81

A rare cause for knee locking: Nodular synovitis

Department of Orthopedics, Kasturba Medical College, Manipal University, Manipal, Karnataka, India

Date of Web Publication7-Jan-2016

Correspondence Address:
Sandeep Vijayan
Department of Orthopedics, Kasturba Medical College, Manipal University, Manipal - 576 104, Karnataka
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/1319-6308.167755

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Locking symptoms in the knee joint generally occur due to meniscal tears and loose bodies. The purpose of this report is to describe a case of nodular synovitis, an intra-articular tenosynovial giant-cell tumor, as a rare differential diagnosis for locking of the knees. Arthroscopic removal ensured prompt symptomatic relief without any recurrence at 1-year follow-up. Nodular synovitis has a better prognosis with limited risk of local recurrence. There is no role for complete synovectomy or postoperative radiotherapy. Knee arthroscopy is the procedure of choice, and prompt symptomatic relief is the usual outcome expected; however, a close follow-up is still warranted to look for recurrence.

  Abstract in Arabic 

سبب نادرلانغلاق الركبة: التهاب الغشاء المفصلي العنقودي لغضروف الركبة
الهدف:الغرض من هذا التقرير هو وصف حالة التهاب الغشاء المفصلي العنقودي لغضروف الركبة ، وبالتجديد خلايا ورمية كبيرة للغضروف الوتري الداخلي كحالة تشخيص ثانوي تادر لانغلاق الركبة. تمت ازالة البورم عن طريق المنظار ثم المتابعة لمدة سنة لزوال الأعراض و عدم ظهور الورم مرة أخرى. التوقعات لالتهاب الغشاء المفصلي جيدة مع محدودية مخاطر عودة ظهور الورم موضعيا مرة أخرى. و اتضح انه لا حاجة لاستئصال الغشاء الغضروفي بالكامل أو العلاج الإشعاعي بعد الجراحة. ونخلص من ذلك ان منظار الركبة هو الإجراء الأمثل لعلاج مثل هذه الحالات خاصة زوال الأعراض وهو النتيجة المتوقعة. إلاّ أن المتابعة اللصيقة ضروروية لضمان عدم ظهور الأعراض مجدداً.

Keywords: Arthroscopy, knee locking, nodular synovitis

How to cite this article:
Vijayan S, Madi S, Naik M, Rao SK. A rare cause for knee locking: Nodular synovitis. Saudi J Sports Med 2016;16:79-81

How to cite this URL:
Vijayan S, Madi S, Naik M, Rao SK. A rare cause for knee locking: Nodular synovitis. Saudi J Sports Med [serial online] 2016 [cited 2023 Feb 8];16:79-81. Available from: https://www.sjosm.org/text.asp?2016/16/1/79/167755

  Introduction Top

In the spectrum of benign synovial proliferative lesions, nodular synovitis constitutes an intra-articular slow growing localized tumor arising from the synovial tissue of the joint. This intra-articular giant cell tumor (GCT) of tendon sheath is termed as “nodular synovitis” in order to distinguish them from those arising from the synovial sheath of tendons, which are common in hands and feet. Clinically, patients present with chronic knee pain, fullness or a palpable mass. Locking of the knee joint is a symptom frequently seen in conditions of mechanical derangements such as osteochondral loose bodies or meniscal tears. However, rarely, these intra-articular solitary benign tumors can cause the mechanical block to knee extension producing locking symptoms. With an estimated prevalence of 1.8/1,000,000 inhabitants, diagnosing nodular synovitis based on clinical manifestations can be challenging.[1] Moreover, there are no characteristic magnetic resonance imaging (MRI) features typical of nodular synovitis, and the final word on diagnosis is only by histopathological evaluation. In the index case, MRI was overlooked, as the tumor masqueraded as a benignly appearing intra-articular cartilaginous loose body. The importance of having a high index of suspicion for these tumors and conducting a histopathological examination of such suspicious 'loose' bodies is underscored.

  Case Report Top

A 40-year-old lady, without any preexisting medical co-morbidities, presented to our knee clinic with complains of intermittent locking of her left knee joint for the past 6 months. It was also associated with dull aching pain over the anterior aspect of the knee which aggravated on sitting cross legged and climbing stairs. There was no history of trauma, instability or swelling around the knee. There was no history of the involvement of other joints. Clinical examination of her left knee was inconspicuous, except for minimal joint effusion. The plain X-rays (anteroposterior and lateral views) of the knee were unremarkable. MRI of the knee showed a cartilaginous loose body measuring 2.2 cm × 1.3 cm in the anterior aspect of joint with thinning of retropatellar cartilage over medial facet in T1-weighted images [Figure 1]. With the preoperative diagnosis of an intra-articular cartilaginous loose body, arthroscopy was performed. Standard knee arthroscopic portals (anteromedial and anterolateral) were made, and the joint was inspected. A suspicious, solitary, brown, pedunculated mass of size 4 cm × 3 cm × 2 cm was noted in the anterior inter-meniscal area [Figure 2]. The mass was excised in total and extirpated out through the anteromedial portal and sent for histopathological examination [Figure 3]. The microscopic picture showed a tumor composed of mononuclear cells, giant cells, and few hemosiderin laden macrophages with occasional mitotic figures, typical of GCT of tendon sheath [Figure 4]. Postoperative days were uneventful. The patient has been under close follow-up for last 1½ year and remains asymptomatic without any recurrence. The patient has given her consent to document this case for publication.
Figure 1: Magnetic resonance imaging T1-weighted image: Showing a small nodular intra-articular mass in the anterior inter-meniscal area

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Figure 2: Arthroscopic image showing the loose body, which appears tan to brown in color

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Figure 3: Arthroscopically excised specimen

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Figure 4: Histopathology (H and E, ×200) photomicrograph showing tumor composed of an admixture of osteoclast-like giant cells and stromal cells

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  Discussion Top

Benign proliferative synovial lesions are a spectrum of diseases arising from the synovium of joints, tendon sheath, and bursa. Within the joint, it is categorized into localized (nodular synovitis) and diffuse (pigmented villonodular synovitis [PVNS]) forms. Nodular tenosynovitis is the GCT of tendon sheath, commonly seen in hands and feet; and its intra-articular focal form is nodular synovitis. Further, fibrous histocytoma of synovium, pigmented nodular synovitis, benign synovioma, and fibrous xanthoma of the synovium are all names for the same condition that are used interchangeably in the literature creating an element of nomenclature confusion. For long, the etiology was thought to be of reactive origin, probably posttraumatic or degenerative, (adding more confusion to the present terminology), but newer evidence is suggestive of neoplastic origin.[2] It is extremely important to make a distinction between local nodular synovitis and the diffuse PVNS, as their biological behavior varies vastly. Nodular synovitis is typically a well-defined, solitary nodule, and unlike PVNS, not associated with hemorrhagic or xanthochromic effusion.[3] Two-third cases of nodular synovitis arises within the infrapatellar fat pad, while other less common locations include the suprapatellar pouch, intercondylar notch, and posterior cruciate ligament.[4] The mean age of presentation is between third to fifth decades with no specific sex predilection.[1] Clinical presentation is usually nonspecific owing to slow-growing nature of these lesions, with vague anterior knee pain being the most common presentation.[5] Rarely, there can be symptoms of mechanical derangement, mimicking meniscal tears or osteochondral loose bodies.

Plain radiographs are usually unremarkable, and MRI is the preferred investigation, however, there are no characteristic magnetic resonance appearances. MRI shows a well-defined, small nodular pedunculated or sessile, intra-articular soft tissue mass. T1-weighted images show a signal intensity similar to that of surrounding skeletal muscle and T2-weighted signal intensity is variable.[4] In the index case, the tumor was identified as a loose body with a signal intensity similar to that of cartilage on all sequences. Further, retropatellar cartilage thinning over the medial facet directed us to believe that this was the possible source of the loose body. Despite the younger age of presentation, it must be noted that it is not uncommon to find degenerative changes in the joint, as seen in the index case.

Grossly, these lesions are usually 1–4 cm in size. It is typically a well encapsulated, nodular, pedunculated mass with tan to brown color. Nodular synovitis is histologically similar to PVNS, with features of synovial proliferation along with scattered multinucleated giant cells, macrophages, fibroblasts, and xanthoma cells. However, there is conspicuous absence of frond-like projections from synovium and scanty hemosiderin deposition.

Knee arthroscopy is the procedure of choice from both diagnostic and therapeutic perspective. As the tumor is mostly confined within the limits of the joint and small in size, complete excision can be accomplished by the arthroscopic procedure. This also gives the opportunity to inspect the joint (to rule out associated causes for locking symptoms) and also address any chondromalacic changes. Formal joint arthrotomy is indicated in exceptionally large sized tumors or tumors located in areas difficult to approach by arthroscopy. Unlike in PVNS, total synovectomy or additional radiosynovirthesis is not required.[1] The recurrence rate for nodular synovitis is believed to be 10–20%.[6] Nodular synovitis has a better prognosis than PVNS. However, a close follow-up is still warranted to look for recurrence.

  Conclusion Top

Nodular synovitis is a rare cause of anterior knee pain and locking. Unlike pigmented villonodular synovitis, nodular synovitis has a better prognosis with limited risk of local recurrence. There is no role for complete synovectomy or postoperative radiotherapy. Knee arthroscopy is the procedure of choice, and prompt symptomatic relief is the usual outcome expected; however, a close follow-up is still warranted to look for recurrence.

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Conflicts of interest

There are no conflicts of interest.

  References Top

Perka C, Labs K, Zippel H, Buttgereit F. Localized pigmented villonodular synovitis of the knee joint: Neoplasm or reactive granuloma? A review of 18 cases. Rheumatology (Oxford) 2000;39:172-8.  Back to cited text no. 1
Weiss SW, Goldblum JR, editors. Benign tumors and tumor-like lesions of synovial tissue. In: Enzinger and Weiss's Soft Tissue Tumors. 4th ed. St. Louis: Mosby; 2001. p. 1037-62.  Back to cited text no. 2
Jelinek JS, Kransdorf MJ, Shmookler BM, Aboulafia AA, Malawer MM. Giant cell tumor of the tendon sheath: MR findings in nine cases. AJR Am J Roentgenol 1994;162:919-22.  Back to cited text no. 3
Huang GS, Lee CH, Chan WP, Chen CY, Yu JS, Resnick D. Localized nodular synovitis of the knee: MR imaging appearance and clinical correlates in 21 patients. AJR Am J Roentgenol 2003;181:539-43.  Back to cited text no. 4
Dines JS, DeBerardino TM, Wells JL, Dodson CC, Shindle M, DiCarlo EF, et al. Long-term follow-up of surgically treated localized pigmented villonodular synovitis of the knee. Arthroscopy 2007;23:930-7.  Back to cited text no. 5
Sheppard DG, Kim EE, Yasko AW, Ayala A. Giant-cell tumor of the tendon sheath arising from the posterior cruciate ligament of the knee: A case report and review of the literature. Clin Imaging 1998;22:428-30.  Back to cited text no. 6


  [Figure 1], [Figure 2], [Figure 3], [Figure 4]

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