The frequency of Baker's cysts associated with meniscal tears

OUP accepted manuscript

A 49-year-old patient, with a maternal history of arthritis, presented with an extra-capsular lump of the left knee. Following magnetic resonance imaging (MRI) scan and excision biopsy, the lump proved to be a benign ganglion cyst. The scan had also shown focal subchondral cyst formation and articular cartilage wear in the medial femoral condyle and patella, with no other abnormality. Four years later, she presented with identical symptoms and signs in the right knee. MRI scan confirmed a symmetrical pattern of ganglion and subchondral cyst location and size. Although both ganglion and subchondral cysts of the knee are common, their development is poorly understood and this combination of cyst formation and chondral wear has not been previously documented. Symmetry of end-stage knee osteoarthritis (OA) is recognized by clinicians. We speculate that OA of the knee begins asymptomatically with point-specific loss of articular cartilage, typically reflecting an inherent and bilateral vulnerability to degeneration.

Factors affecting Baker cyst volume, with emphasis on cartilage lesion degree and effusion in the young and middle-aged population

Background

The principal aim of this study was to investigate the presence of factors affecting Baker’s cyst volume in young and middle-aged populations.

Methods

Open cyst excision with valve and capsule repair, as well as knee arthroscopy, were used to treat eighty-five patients. The cases were categorized in terms of age, effusion, chondral lesion degree, meniscal tear degree, and Lindgren scores. An ultrasonography (USG) device was used to calculate the cyst volume. The IBM-SPSS 22 program was used for statistical analysis and to assess the relationships between variables using Spearman’s correlation tests.

Results

The degree of chondral lesion was moderately and positively correlated with cyst volume in the total population (correlation coefficient: 0.469; p < 0.05).

The degree of the chondral lesion was moderately and positively correlated with the degree of effusion (correlation coefficient: 0.492; p < 0.005). The cyst volume was weakly and positively correlated with the degree of effusion (correlation coefficient: 0.20; the correlation was at the limits of statistical significance p = 0.07 < 0.08).

Conclusions

This study revealed that an increase in chondral lesion severity increases the amount of effusion and cyst volume.

Comparison of clinical outcomes associated with arthroscopic cyst wall preservation or resection in the treatment of popliteal cyst: a systematic review and meta-analysis

OBJECTIVE

Arthroscopy is commonly used to treat popliteal cysts, but the influence of the cyst wall on treatment outcomes remains controversial. The goal of this study was to compare clinical outcomes associated with arthroscopic cyst wall resection versus preservation in patients undergoing treatment for popliteal cysts.

METHODS

We searched the PubMed, Embase, Web of Science, and Cochrane Library databases to identify all relevant articles published as of April 2020. STATA v15.1 was used for all statistical analyses. Relative risk (RR) and corresponding 95% confidence intervals (CIs) pertaining to study outcomes were calculated. Study heterogeneity was evaluated using the I² statistic and the χ² test, with I² > 50% and P < 0.10 as respective significance threshold values. The risk of bias was gauged with the Cochrane Collaboration's risk of bias tool and the Newcastle-Ottawa Scale (NOS).

RESULTS

In total, 18 relevant studies were included in this meta-analysis, of which 16 were observational studies and 2 were randomized controlled trials (RCTs). These studies included 573 total patients, of whom 346 underwent arthroscopic cyst resection and 227 underwent arthroscopic cyst preservation. Pooled analyses revealed that clinical outcomes (RR = 0.98, 95% CI 0.94-1.00) and postoperative recurrence rates (RR = 0.90, 95% CI 0.85-0.95) were significantly better among patients that underwent cyst wall resection relative to those that underwent cyst wall preservation (RR = 0, 95% CI 0-0.02 and RR = 0.05, 95% CI 0.02-0.10, respectively). However, complications occurred more often in the cyst wall resection group relative to the cyst wall preservation group (RR = 0.05, 95% CI 0.01-0.12 vs. RR = 0.01, 95% CI 0-0.03). Sensitivity analyses confirmed the stability of these pooled results, and we detected no significant risk of publication bias.

CONCLUSIONS

Relative to cyst wall preservation, popliteal cyst wall arthroscopic resection can yield more satisfactory clinical results and decrease rates of recurrence, but can also increase the incidence of complications. Future prospective studies comparing the outcomes associated with cyst wall resection and preservation will be required to validate our results.

Clinical, Radiographic, and Ultrasound Findings Between Simple and Complicated Baker's Cysts

PURPOSE

The aim of the study was to compare the clinical, radiographic, and ultrasound findings between simple and complicated Baker's cysts.

METHODS

Forty-seven knees with Baker's cysts in 45 patients with knee pain were identified from a chart review. Baker's cysts were classified as simple or complicated according to ultrasound findings. Clinical data, including duration of knee pain, visual analog scale score, Kellgren-Lawrence grade, ultrasound findings, including the size and sonomorphology of the BC, severity of osteophytosis, thickness of joint effusion, meniscal tear, and synovial proliferation of the two types of BC, were compared.

RESULTS

There were 22 knees with a simple cyst and 25 knees with a complicated cyst. The thickness of the suprapatellar effusion in complicated Baker's cysts (5.7 ± 3.0 mm) was significantly greater than that in simple Baker's cysts (3.8 ± 3.2 mm), and the presence of synovial proliferation in the suprapatellar recess was significantly higher in complicated Baker's cysts (22 knees, 88.0%) than in the simple Baker's cysts (12 knees, 54.5%). However, there were no significant differences in demographic, radiographic, and other ultrasound parameters between the two types of BC.

CONCLUSIONS

Synovial proliferation with larger effusion in the suprapatellar recess was more associated with complicated BC than simple BC.

Infected Baker's Cyst: A New Classification, Diagnosis and Treatment Recommendations

Introduction:

Baker’s cyst has a high prevalence in adult population. Despite being usually asymptomatic, cyst complications may develop, such as an infection, rupture and content dissemination into the calf. This clinical presentation has a low incidence with few reports in the literature. We have not found any publication describing a systematic approach for its treatment. The purpose of this study is to propose a new classification, diagnosis, and treatment recommendations based on a case report and a literature review to guide physicians on the best course of treatment.

Case Report:

A 53-year-old man presented with sudden left popliteal pain associated with progressive knee and calf swelling and limited knee flexion. After the initial evaluation, a Baker’s cyst rupture and dissemination into the calf, associated with a septic arthritis, were diagnosed. An arthroscopic surgical irrigation of the knee and open debridement of the calf collection were performed.

Conclusion:

Our classification may allow an accurate and structured description of the different stages of Baker’s cyst presentations, with simplification of the clinical description, diagnosis, and treatment approaches.

Arthroscopic treatment of popliteal cyst using a figure-of-four position and double posteromedial portals

PURPOSE

The purpose of this study was to introduce a modified arthroscopic treatment technique for popliteal cyst and hypothesize that this modified technique would provide good clinical efficacy and low recurrence rate.

METHODS

From January 2013 to January 2017, 34 patients with symptomatic popliteal cysts were treated with our technique. A figure-of-four position and double posteromedial portals were used to achieve adequate enlargement of the posteromedial valvular opening between the cyst and the joint cavity and complete excision of the cyst wall. MRI was used to detect the recurrence of the popliteal cyst, and the Rauschning and Lindgren score was recorded to evaluate the clinical outcome.

RESULTS

All patients were followed up with a mean period of 14.8 months (range, 12 to 36 months). Associated intra-articular lesions were found and treated in all cases. Degenerative cartilage damage was the most common pathology, which affected 23 (67.6%) of the cases. The Rauschning and Lindgren score improved significantly after surgery, and no evidence of recurrence was found from MRI in any case.

CONCLUSIONS

Our modified arthroscopic treatment technique, using a figure-of-four position and double posteromedial portals, is effective and safe for treating popliteal cyst.

Treatment of baker cyst, by using open posterior cystectomy and supine arthroscopy on recalcitrant cases (103 knees)

Background

Associated joint disorders with popliteal cysts were stated approximately between the ranges of 41–83 % in all reported cases. Combined treatment strategies that eliminate intra-articular pathologies and cyst- associated valve mechanisms are thought to be a good option in treatment of the disease. In this study, our main objective is to present clinical results of our combined treatment results, which includes posterior cyst excision with supine arthroscopic intervention, targeting intra-articular pathologies on recalcitrant cases.

Methods

One hundred three knees of 100 patients treated with posterior open cystectomy with valve and repair of posterior capsule, in addition to arthroscopic treatment of intra-articular lesions, were included in the study. Preoperative magnetic resonance imaging (MRI) studies were performed in order to evaluate location of Baker cysts behind the knee. Rauschning-Lindgren and Lysholm Knee Scoring Scales were used to assess pre/post-operative knee functions.

Mann-Whitney U test was used to evaluate the differences between genders in comparison of Lysholm and Lindgren scores. Mean age within gender groups was compared using independent samples t-test. Wilcoxon test was used to compare the change in Lysholm and Lindgren scores. A p-value of less than 0.05 was considered to show a statistically significant result.

Over the 1-year follow-up period, US and MR imaging was performed only with symptomatic patients.

Results

Cyst recurrence was seen only in 2 (1.94 %) patients. Post-operative Lysholm Knee and Lindgren knee scores demonstrated improvement in knee function and general comfort level of the patients.

Conclusions

Our midterm follow-up (Mean: 39 Months) results showed that open cyst excision with valve and capsule repair with knee arthroscopy that targets associated intra-articular pathologies reduced the pain and improved the knee function in those patients.

Level of evidence

IV (Retrospective clinical study without comparison group).

Baker's Cyst: Diagnostic and Surgical Considerations

Context:

Popliteal synovial cysts, also known as Baker’s cysts, are commonly found in association with intra-articular knee disorders, such as osteoarthritis and meniscus tears. Histologically, the cyst walls resemble synovial tissue with fibrosis evident, and there may be chronic nonspecific inflammation present. Osteocartilaginous loose bodies may also be found within the cyst, even if they are not seen in the knee joint. Baker’s cysts can be a source of posterior knee pain that persists despite surgical treatment of the intra-articular lesion, and they are routinely discovered on magnetic resonance imaging scans of the symptomatic knee. Symptoms related to a popliteal cyst origin are infrequent and may be related to size.

Evidence Acquisition:

A PubMed search was conducted with keywords related to the history, diagnosis, and treatment of Baker’s cysts—namely, Baker’s cyst, popliteal cyst, diagnosis, treatment, formation of popliteal cyst, surgical indications, and complications. Bibliographies from these references were also reviewed to identify related and pertinent literature.

Study Design:

Clinical review.

Level of Evidence:

Level 4.

Results:

Baker’s cysts are commonly found associated with intra-articular knee disorders. Proper diagnosis, examination, and treatment are paramount in alleviating the pain and discomfort associated with Baker’s cysts.

Conclusion:

A capsular opening to the semimembranosus–medial head gastrocnemius bursa is a commonly found normal anatomic variant. It is thought that this can lead to the formation of a popliteal cyst in the presence of chronic knee effusions as a result of intra-articular pathology. Management of symptomatic popliteal cysts is conservative. The intra-articular pathology should be first addressed by arthroscopy. If surgical excision later becomes necessary, a limited posteromedial approach is often employed. Other treatments, such as arthroscopic debridement and closure of the valvular mechanism, are not well studied and cannot yet be recommended.

Treatment of popliteal cysts via arthroscopic enlargement of unidirectional valvular slits

OBJECTIVE

The aim of the present study was to investigate the efficacy of arthroscopic enlargement of unidirectional valvular slits for the treatment of popliteal cysts and to evaluate potential factors affecting the outcomes of our arthroscopic procedure.

METHODS

Twenty-nine patients aged 43-77 years with popliteal cysts were treated with arthroscopic cyst decompression. Surgery was performed via two posterior portals after creating a transseptal portal. Rauschning and Lindgren clinical score, magnetic resonance images, and osteoarthritic grade were evaluated pre- and postoperatively, and cartilage degeneration class was confirmed via arthroscopy. The mean follow-up period was 22.9 ± 14.6 months (range, 9-60 months).

RESULTS

Twelve cysts disappeared completely (group D), while 16 reduced and one enlarged (group R) in size by the final follow-up. Twenty-two (75.9%) of 29 popliteal cysts diminished to a volume that was less than 10% of the preoperative volume. Clinical scores improved in 93.1% of the patients, and more patients (68.8%) in group R had positive joint effusion at the final follow-up compared with group D (17.7%; p < 0.01).

CONCLUSIONS

Arthroscopic cyst decompression was effective in the treatment of symptomatic popliteal cysts. Intra-articular pathologies associated with joint effusion should be corrected simultaneously.

Arthroscopic Treatment of Popliteal Cyst: A Direct Posterior Portal by Inside-Out Technique for Intracystic Debridement

Popliteal cysts are characterized by enlargement of the gastrocnemius-semimembranosus bursa. The pathogenesis includes a valvular opening between the knee joint and the bursa, and associated intra-articular pathology may give rise to knee effusion. The mainstay of treatment is conservative. If popliteal cysts are symptomatic, analgesia, aspiration, and steroid injection therapy may be considered, but most recur rapidly. In the past, open excision was an option if they remained symptomatic, but the associated recurrence rate was high. One important reason was that the intra-articular pathology causing the knee effusion was not treated. We present an alternative minimally invasive arthroscopic treatment using dye (methylene blue) directly injected into the cyst, which will leak from the cyst into the joint, to identify the valvular opening. The thickened valve is opened using a basket forceps and then enlarged using a motorized shaver to disrupt the 1-way mechanism between the joint and bursa, as well as to establish an unobstructed freeway connection between them. We also present a safe technique to create a direct posterior portal. Intracystic debridement of the fibrous membrane, nodules, and septa through this portal will decrease the recurrence rate of the popliteal cyst.

The association between Baker's cyst and medial meniscal tear in patients with symptomatic knee using ultrasonography

INTRODUCTION

There are nearly no studies about the association between Baker's cyst (BC) and medial meniscal tear (MMT) using ultrasonography.

PATIENTS AND METHODS

Nonselected patients who were referred for ultrasonography for the evaluation of knee pain were recruited. Demographic, clinical, and ultrasound parameters were documented.

RESULTS

One-hundred and nineteen patients were included and 131 knees were evaluated. There were 59 (~50%) female patients and mean age of 46.4±17.7 years. BC was found in 31 knees (23%). BC was significantly associated with MMT (P=.029) and age (P=.002) after adjusting for other covariates.

CONCLUSIONS

BC was strongly associated with MMT regardless of other intraarticular abnormalities.

The concept of three-dimensional hold of both circumferential and radial collagen fibres of the meniscus

Collagen fibres of the meniscus arrange into two main orientations: circumferential fibres parallel to the long axis of the meniscus and radial fibres perpendicular to the long axis of the meniscus. Meniscal sutures are placed either in vertical or in horizontal orientations. Vertical sutures better hold circumferential fibres because it encircles them like a rope holding a bunch of tree branches. In the same manner, horizontal sutures better hold radial fibres. The "Simplified Cruciate Suture" consists of two vertical oblique sutures. Placing two vertical sutures in an oblique orientation captures greater meniscal tissue volume, holds and grasps both circumferential and radial collagen fibres of the meniscus into a three-dimensional plane with eventual high fixation strength of the repaired meniscal tear. Simplified cruciate suture is indicated for the repair of long bucket handle tears where it is placed in the middle of the tear like an anchor, and additional vertical and horizontal sutures are placed anterior and posterior to it as needed. Level of evidence V.

Popliteal cysts: a current review

Baker's cyst, or popliteal cyst, is a fluid-filled mass that is a distention of a preexisting bursa in the popliteal fossa, most commonly the gastrocnemio-semimembranosus bursa. This bursa is unique in that it communicates with the knee joint, unlike other periarticular bursae, via an opening in the joint capsule posterior to the medial femoral condyle. Many have theorized that this opening creates a valve-like mechanism in the presence of effusion that contributes to the formation of these cysts in adults. Popliteal cysts rarely manifest alone and are most often found in conjunction with other intra-articular pathologies and inflammatory conditions, such as osteoarthritis, meniscus tears, and rheumatoid arthritis. In children, popliteal cysts are only occasionally associated with these conditions and are more often an incidental finding discovered during a routine physical examination. Popliteal cysts may present as either a chronically persistent or relapsing condition or as an acute and dramatic condition that can occur in the case of cyst rupture presenting as pseudothrombophlebitis. Ultrasound and magnetic resonance imaging have proven to be consistent and accurate in the confirmation of popliteal cysts, with magnetic resonance imaging becoming the modern imaging modality of choice. This review discusses the anatomy and etiology of popliteal cysts, describes the common clinical presentations, reviews the differential diagnoses, and provides guidance for proper diagnostic imaging. It also provides a comparison of current conservative, minimally invasive, and invasive treatment options, along with a discussion of results. Postoperative rehabilitation depends largely on the condition associated with the popliteal cyst.

Ruptured Baker's cyst with compartment syndrome: an extremely unusual complication

A 69-year-old man presented with sudden onset of pain with acute tense swelling of his left leg. Initially he was treated empirically with antibiotics for cellulitis while the possibility of deep vein thrombosis was ruled out. His symptoms gradually worsened with progressive distal neurological deficit and increasing pain. Further investigations suggested that he had a ruptured Baker's cyst in the calf with development of compartment syndrome.

Equine articular synovial cysts: 16 cases

OBJECTIVE

To report the clinical findings, diagnosis, treatment and outcome of equine patients with articular synovial cysts.

STUDY DESIGN

Retrospective case series.

ANIMALS

Horses (n = 16) with articular synovial cysts.

METHODS

Horses diagnosed with articular synovial cysts (1988-2009) at 2 veterinary teaching hospitals were studied. Signalment, history, clinical signs, diagnostic methods and treatment were retrieved and telephone follow-up was obtained.

RESULTS

Sixteen horses with articular synovial cysts were identified. Lameness was the reason for referral in most (n = 9) horses. Diagnosis was based on a combination of palpation and imaging studies, including radiography, ultrasonography and/or arthrography. Excision of the cyst was performed in 8 horses. Outcome was available for 4 surgically and 2 conservatively treated horses. Lameness resolved in 3 horses treated surgically and the 4th died for unrelated reasons. The 2 conservatively treated horses performed satisfactorily for the rest of their career.

CONCLUSIONS

Equine articular synovial cysts are rare and can be associated with lameness. The cysts had a synovial lining in all horses where it was assessed. Surgical excision may be successful in resolving the lameness and allowing selected horses to return to work.

Arthroscopic treatment of popliteal cysts: clinical and magnetic resonance imaging results

PURPOSE

This study examined the functional and magnetic resonance imaging (MRI) outcomes of popliteal cysts with combined intra-articular pathologies that were treated arthroscopically by decompression and a cystectomy through an additional posteromedial cystic portal.

METHODS

From January 2003 to March 2008, 31 patients were treated with a modified arthroscopic technique to decompress a popliteal cyst. The connecting valvular mechanism was found in all cases at the posteromedial compartment through the anterolateral viewing portal, and it was corrected by resecting the capsular fold through the posteromedial working portal. For cysts with multiple fibrous septa, an additional portal, the so-called posteromedial cystic portal, was used for complete cyst removal. The functional outcome was evaluated by use of the Rauschning and Lindgren knee score. All patients were evaluated by MRI, which documented the popliteal cyst and associated intra-articular lesions preoperatively and at follow-up.

RESULTS

All patients could return to their previous daily activities with few or no limitations, and no additional surgery was required after a mean follow-up of 36.1 months (range, 12 to 72 months). The Rauschning and Lindgren knee score showed improved clinical features at the final follow-up in 94% of patients. The follow-up MRI study showed that the cyst had disappeared in 17 knees (55%) and had reduced in size in 14 knees (45%) in the 31 patients. The mean cyst size was reduced significantly from 6.8 to 0.8 cm (P < .0001).

CONCLUSIONS

The described arthroscopic technique with or without an additional posteromedial cystic portal is effective for treating popliteal cysts with combined intra-articular lesions. More importantly, follow-up MRI showed that the cyst size was reduced or it had disappeared in all cases, although there was no association between the cyst's disappearance and the follow-up clinical score.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Recurrent popliteal cyst in an adult: a case report and review

Popliteal cysts are typically secondary to an intra-articular pathology in adults but may occur as primary lesions unrelated to knee injury. Careful examination of any mass forming on the posterior aspect of the knee is needed to differentiate benign from malignant conditions. Asymptomatic cysts are often treated conservatively, whereas surgical intervention is recommended for troublesome cysts and for those related to intra-articular derangements. Surgical intervention focused on amelioration of intra-articular derangements and the communication between the knee and the popliteal cyst results in cyst recurrence of less than 5%. A report of a recurrent popliteal cyst, in spite of aggressive surgical intervention, is presented.

Giant synovial cyst of knee treated arthroscopically through a cystic portal

Synovial cysts are well-defined fluid filled cysts that can extend for a variable distance outside the joint space. These cysts can sometimes grow to a large size making its treatment challenging especially when associated with intra-articular pathologies. We describe a case of giant synovial cyst arising from the left knee and extending to the medial proximal calf in a 77-year old female who presented with knee joint pain, episodes of locking and calf mass occurring within 2 months of onset. Imaging studies also showed associated medial and lateral meniscal tears with medial compartment and patellofemoral osteoarthritis. The cyst was treated by disrupting the valvular mechanism using a standard posteromedial portal and complete excision of the cyst wall via a posteromedial cystic portal. The meniscal lesions were dealt with through the standard anterior portals. At 25-month follow up there were no signs of recurrence of the cyst clinically or with MRI. The cystic portal technique is effective in treating a giant synovial cyst of the knee even in the presence of meniscal tears and high grade chondral lesions.

MR Imaging of Cysts, Ganglia, and Bursae About the Knee

Cystic lesions around the knee comprise a diverse group of entities, ranging from benign cysts to complications of underlying diseases such as infection, arthritis, and malignancy. Their diverse causes result in varied prognoses and therapeutic options. Although the presentation of cystic masses may be similar, their management may differ, thus highlighting the importance of appropriate categorization. MR aids in the characterization of lesions by first localizing them, and then defining their relationship with adjacent structures and identifying any additional abnormalities. For the purpose of this article, the authors limit the scope of their discussion to benign cysts, ganglia, and bursae about the knee.

Ganglion cysts at the gastrocnemius origin: a series of ten cases

OBJECTIVE

To describe ganglion cysts arising close to the origin of the medial and lateral head of gastrocnemius as identified on magnetic resonance (MR) imaging.

DESIGN AND PATIENTS

We present a series of ten cases of ganglion cysts arising close to the gastrocnemius origin from the medial and lateral femoral condyles. These were collected over a 6-year period from our imaging database. All patients attended for routine MR imaging of the knee with a variety of clinical presentations. Data collected included patient demographics, ganglion size, ganglion site, clinical presentation and ancillary MR imaging findings. The ten patients in this series consisted of seven males and three females, five right and five left knees, age range 27-68 years, mean age 40.6 years.

RESULTS

The mean maximal dimension of the ganglion cysts was 26 mm, range 15-40 mm. The medial gastrocnemius origin was involved in eight patients and the lateral origin in two patients. The MR imaging findings consisted of both uni- and multi-loculated cysts, often containing numerous septations with fluid signal characteristics. The cysts were extra-capsular with no clear communication with the joint. One patient presented with a popliteal soft tissue mass and none of the cases required surgical intervention for cyst removal.

CONCLUSIONS

MR imaging may identify ganglion cysts arising in an intra- or extra-articular site around the knee. This series documents the MR imaging characteristics of ganglion cysts arising close to the gastrocnemius origin and discusses the relevance of this imaging finding.

The popliteal cyst

A popliteal cyst, originally called Baker's cyst, is a synovial fluid-filled mass located in the popliteal fossa. The most common synovial popliteal cyst is considered to be a distension of the bursa located beneath the medial head of the gastrocnemius muscle. Usually, in an adult patient, an underlying intra-articular disorder is present. In children, the cyst can be isolated and the knee joint normal. The anatomy, etiopathogenesis, clinical presentation, differential diagnosis, imaging and treatment modalities of the popliteal cyst are presented. The authors try to answer some questions dealing with this condition. Is the cyst isolated, can it be treated as such, is its origin always well-defined and does surgical excision provide a permanent cure?

Arthroscopic treatment of popliteal cyst and visualization of its cavity through the posterior portal of the knee

In regard to arthroscopic treatment of popliteal cysts, we explored the refuted pathology for popliteal cysts proposed by others. Here we introduce an arthroscopic technique using posterior portals to treat a popliteal cyst based on our observation that the opening of the cyst in the joint is a slit-like structure in the posterior wall of the capsule. By disrupting this slit-like structure with our procedure, the popliteal cyst ceased to be palpable and was no longer symptomatic. This technique also provides excellent arthroscopic visualization of the cavity of the popliteal cyst through the knee joint approach. After completion of the resection of the opening, we can easily insert an arthroscope into the cavity of the popliteal cyst from the posteromedial portal through the resected opening. Arthroscopic visualization of the cavity of the cyst showed that the inside wall of the cavity was smooth and had no synovitis. We believe that to disrupt this slit structure is the most pathologically reasonable procedure to treat popliteal cysts surgically.

Dissecting popliteal cyst resulting from a fragmented, dislodged metal part of the patellar component after total knee arthroplasty

Dissecting popliteal cyst is an uncommon complication after total knee arthroplasty, occurring mainly as a result of either rheumatoid arthritis or a malfunctioning knee prosthesis. Its association with a failed metal-backed patellar component has not been reported since the introduction of the resurfacing of the patella with this kind of design in 1980. We present a case of a late fracture-dislocation of the metal part of the patellar component that migrated to the posterior popliteal fossa, resulting in a cystic mass formation caused by a foreign body granuloma. The patient was treated successfully with a 2-stage operation: first, revision of the total knee arthroplasty and, second, excision of the cyst. The patient had a pain-free functional knee 7 years after surgery, with no recurrence of the symptoms or the popliteal cyst.

Popliteal cysts in adults. Prevalence, associated intraarticular lesions, and results after arthroscopic treatment

The objective of this prospective study was to determine the prevalence of popliteal cysts and the associated intraarticular lesions in a group of 100 patients scheduled for arthroscopic surgery of the knee and to evaluate the results of arthroscopic treatment for these intraarticular lesions without removal of the cyst. One hundred patients without any knee complaints served as a control group. The diagnosis of a popliteal cyst was made on the basis of ultrasonography. The prevalence of popliteal cysts was 20% in the study group and 0% in the control group. Patients with a popliteal cyst had a significantly higher prevalence of medial meniscal tears (70% versus 19%) and of chondral lesions (85% versus 28%). Tears of the lateral meniscus, however, were more evenly distributed (20% versus 36%). Sixteen of 20 patients with a popliteal cyst were available for a follow-up examination 1 to 3 years after the arthroscopic procedure. Eleven popliteal cysts had persisted. Chondral lesions were the most relevant prognostic factor; all patients with persisting cysts had grade III or grade IV lesions. We conclude that the popliteal cyst is a secondary phenomenon and that treatment should address the underlying intraarticular lesions. In cases of osteoarthritis it may be impossible to treat the chondral lesion successfully in terms of eliminating the effusion.

MR imaging of Baker cysts --prevalence and relation to internal derangements of the knee

RATIONALE AND OBJECTIVES

To evaluate the prevalence of popliteal cysts in patients studied with magnetic resonance (MR) imaging. Cyst presence and volume will be related to other internal derangement of the knee.

MATERIALS AND METHODS

Three hundred and eighty-two consecutive patients with a MR study of the knee were included. Images were obtained in the three spatial orthogonal planes and evaluated through consensus. Four categories were established for the Baker cyst and synovial fluid (absence, minimum, moderate and massive), and the presence of meniscal, cruciate ligaments and cartilage lesions were recorded. Statistical analysis was carried out with bivariate analysis (chi(2) of Pearson and Gamma tests).

RESULTS

From the 382 patients, 145 had Baker cysts (38.0%). Cyst content was minimum in 99, moderate in 34 and massive in 12. Joint effusion was observed in 269 patients (70.4%), being minimal in 140 patients, moderate in 119 and massive in ten. Meniscal lesions were observed in 195 patients (51%), while 58 patients (15%) had a cruciate ligament lesion. Baker cyst had a statistically significant direct relationship with the presence and quantity of synovial fluid (P=0.002) and with the presence and type of meniscal lesion (P=0.01) but not with cruciate ligaments or cartilage lesions.

CONCLUSIONS

The prevalence of Baker cysts in MR studies of the knee is high. Its presence and volume are related to the quantity of synovial fluid, and to the presence and severity of meniscal lesions.

Cysts and other masses about the knee: identifying and treating common and rare lesions

Masses about the knee are most commonly benign cysts. The diagnosis can often be made with a history and physical exam, but radiographs and MRI are sometimes required, and histologic evaluation is occasionally necessary. Popliteal (Baker's) cysts are often indicative of arthritis; treatment for the underlying pathology may reduce swelling and permit resorption. Meniscal cysts indicate an underlying tear; treatment is resection and cyst excision. Symptomatic ganglion cysts generally require surgical excision. Treatment for bursitis is conservative. The less-common synovial chondromatosis, pigmented villonodular synovitis, synovial sarcoma, and lesions of the proximal tibiofibular joint generally require referral and surgery.