Compartment syndrome secondary to Baker's cyst rupture: A case report and up-to-date review.

Baker's cyst is a distention or enlargement of the gastrocnemius-semimembranosus bursa toward the popliteal fossa which is usually associated with intra-articular pathologies. Rupture or dissection of the Baker's cyst results in extravasation of the cyst content into the calf within intermuscular space under the fascia. This clinical entity, also called pseudothrombophlebitis, is a self-limited condition that usually resolves with supportive treatment. However, in patients using anticoagulants, excessive hemorrhage may cause compartment syndrome in case of cyst rupture. Early diagnosis of compartment syndrome is the most important step in preventing permanent disability. Therefore, compartment syndrome should be kept in mind and ruled out in a patient with pseudothrombophlebitis syndrome under anticoagulation therapy.

INTRODUCTION

Baker's cyst is a distention or enlargement of the gastrocnemius-semimembranosus bursa (GSB) toward popliteal fossa.[1] Communication through a capsular opening between the knee joint cavity and GSB is a common anatomic variant in a normal joint [Figure 1]. Handy reported that Baker's cyst may be found in 5%–32% of symptomatic knees in a review article.[2] In case of chronic knee effusion and increased intra-articular pressure, this anatomic connection works as a check-valve and synovial fluid flows from intra-articular space toward GSB but cannot return to synovial space. This causes gradual distention of GSB and the Baker's cyst comes out. The cyst is usually associated with chronic knee effusion secondary to various intra-articular pathologies, particularly medial meniscal tears, osteoarthritis, and inflammatory arthritis.

Figure 1

Illustration showing the Baker's cyst and its connection with synovial space

Although Baker's cyst usually remains asymptomatic, it may produce knee pain or stiffness with a palpable lump at the posterior aspect of the knee.[134] However, it may cause various complications such as neurovascular entrapment owing to mass effect, infection, cyst rupture, and compartment syndrome. Compartment syndrome secondary to Baker's cyst rupture is a rare complication with few published cases in the literature [Table 1]. However, this complication is a serious condition that can lead to functional impairment and even limb loss. Herein, a patient with compartment syndrome secondary to Baker's cyst rupture was presented.

Table 1

List of previously reported cases with compartment syndrome related with Baker’s cyst rupture in the current literature

Author	Years	Age	Sex	Clinical features	Imaging	Treatment modality	Follow-up and results
Petros et al.[10]	1990	35	Male	Painful and swollen calf	CT: UnremarkableArthrogram: Extravasation of dye posteriorly into the calf	Fasciotomies to decompress the calf compartments	At 4th month, slight numbness in the distribution of the saphenous nerve and persistent edema
Dunlop et al.[5]	1997	58	Male	Painful and swollen calf	Venogram: After clinical suspicion of DVT and 2nd day of treatment, there is no evidence	Fasciotomies to decompress the calf compartments	At 5th week, no demonstrable clinical deficit
Ushiyama et al.[6]	2003	47	Male	Severe pain in the right leg, drop foot, a small mass in the popliteal fossa	X-ray: no abnormalitiesArthrogram: A ruptured popliteal cyst	Fasciotomies to decompress the calf compartments	At a 3rd month, relief of the leg pain, palsy in the right foot
Schimizzi et al.[3]	2006	49	Male	Increased left leg pain and swelling	Doppler: No evidence of DVTMRI: Medial meniscometry and ACL tear, a ruptured Baker cystAfter the 5th day of treatment, an acute increase in pain and swellingX-ray: Notable for the soft-tissue swelling	Rest, elevation, warm compresses, NSAID Re-look: Fasciotomies to decompress the calf compartments	Relief of all symptoms
Hamlet et al.[4]	2012	69	Male	Swollen, painful and red leg Neurological deficit at the common peroneal nerve	USG: A large popliteal cystMRI: A ruptured popliteal cyst with extension into the upper two-thirds of the calf	Fasciotomies to decompress the calf compartments	At 7th month, relief of all symptoms
Moon et al.[7]	2013	49	Male	Left-sole paresthesia and calf pain Neurological deficit at the posterior tibial nerve	USG: A cystic anechoic compressibleMass around the left posterior tibial nerve at the mid one-third area of the lower legMRI: Ruptured baker cyst	Noninvasive treatment (gabapentin, transcutaneous electrical nerve stimulation, electrical stimulation therapy, and physical therapy) for neuropathy	After 2 months, a significant improvement of symptoms
Kim et al.[8]	2014	58	Male	Painful, warm, swollen leg with tenderness Differences in calf circumference No neurological complaints	X-ray: Bilaterally Grade I OAUSG: A cyst connected knee joint was communicated with a fluid collection of the calf	Cyst aspiration, intralesional injection of corticosteroid, NSAID A few weeks later, reaspiration because of calf pain	The pain was relieved after the second aspiration
Wilder et al.[11]	2014	66	Female	Progressive edema, pain	X-ray: No fractureDoppler: No DVTMRI: A ruptured popliteal cyst with intra-cystic hemorrhage	Fasciotomies to decompress the calf compartments	The pain was improved immediately postoperative
Yoo et al.[1]	2014	81	Male	Painful mass at the swollen calf	X-ray: Grade IV OACT: A large mass along the subfascial layerMRI: A large mass extending distally along the subfascia	Open mass excision	At a 2nd week, relief of all symptoms
Marlborough and Venkataraman[9]	2015	68	Male	The painful and swollen calf, loss of sensation over the dorsum of the foot and motor deficit for toes activity	USG: A ruptured hemorrhagic Baker’s cyst	Fasciotomies to decompress the posterior compartment	After the 2nd day, more comfortable
Current case	2018	64	Female	The swollen calf, unable to walk	X-ray: No bony abnormalities Doppler: No DVTMRI: A ruptured Baker’s cyst	Fasciotomies to decompress the posterior compartment	At 6th month, relief of all symptoms

OA: Osteoarthritis, MRI: Magnetic resonance imaging, CT: Computerized tomography, USG: Ultrasonography, X-ray: Plain Radiograph, NSAID: Nonsteroid anti-inflammatory drug, DVT: Deep-venous thrombosis, ACL: Anterior cruciate ligament

CASE REPORT

A 64-year-old female was admitted to the emergency department with a swollen calf and unable to walk for 2 days. Her complaints started suddenly when sitting for a rest after walking 5 km distance. There was no antecedent trauma. Her medical history revealed bilaterally knee osteoarthritis, and she was using oral anti-inflammatory medications irregularly. Moreover, she was using Warfarin for cardiac rhythm disorder.

The patient's complaints worsened within 24 h and her calf became extremely tight and swollen. On admission, she was unable to walk due to intense pain. On physical examination, the calf was tender, warm, and swollen. There was a remarkable difference in the circumference of calf compared to the other side [Figure 2]. Passive dorsiflexion of the ankle, also known Homan's sign, was painful. The knee range of motion was slightly limited. Distal pulses were palpable, but there was hypoesthesia over posterior calf and heel with normal motor functions. All of these findings caused suspicion of compartment syndrome in this patient.

Figure 2

Clinical appearance of the patient's calves from the posterior aspect. Note the swollen left calf with the significant circumferential difference compared to the contralateral side

Plain roentgenograms of the leg showed no bony abnormalities except for swollen soft tissue on the posterior calf [Figure 3]. Doppler ultrasonography (DUS) was negative for deep-venous thrombosis (DVT). Routine laboratory tests were all in normal, including erythrocyte sedimentation rate and C-reactive protein. However, prothrombin time/international normalized ratio was 2.1. The patient was hospitalized for monitoring for possible compartment syndrome, and observed with rest, elevation, and ice compression. Meanwhile, magnetic resonance imaging (MRI) was performed to exclude space-occupying entities. MRI showed the hyperintense collection in the posterior compartment and ruptured Baker's cyst [Figure 4]. Her clinical status did not improve after conservative management within 2 h. Posterior compartment pressure was measured as 40 mmHg due to the persistence of the patient's complaints after MRI. The patient's blood pressure was measured as 135/70 mmHg in simultaneous compartment measurement (ΔP = 30 mmHg). Fasciotomy was planned for the treatment.

Figure 3

Anteroposterior (a) and lateral (b) plain radiographs showing marked soft-tissue swelling

Figure 4

T2 sequence of the calf magnetic resonance imaging. (a) Mucinous collection in the posteromedial calf. (b) The opening of the cyst from the posteromedial border of the medial femoral condyle to knee joint space. (c) Sagittal view of the left calf. (d) Coronal view of the left calf

Fasciotomy was performed through a medial longitudinal incision because alone posterior compartment involvement is considered. The gastrocnemius fascia was incised. 450cc bloody mucinous clot was removed, and soleus fascia was released [Figure 5]. Only skin was closed with superficial sutures and two suction drains were placed. After 24 h from the operation, clinical status was dramatically improved. The microbiological examination and culture of the fluid were negative. The patient was externalized at the 2nd operative day. At 1st month, the patient returned her previous level of activity. Physical examination was totally normal, and the calf was returned to its normal circumference [Figure 6].

Figure 5

Medial longitudinal incision for posterior compartment decompression. The mucinous clot is seen within the posterior compartment

Figure 6

Clinical appearance of the patient's calves at the first month follow-up visit

DISCUSSION

Rupture or dissection of the Baker's cyst results in extravasations of the cyst content into the calf within intermuscular space under the fascia. Cyst rupture usually occurs suddenly, patients feel a sharp pain at the back knee. Then, the calf becomes swollen and tender. Erythema, itching, or ecchymosis around the ankle may also accompany the aforementioned clinical findings. Homan's sign is typically positive in these patients. This clinical entity is known as pseudothrombophlebitis.[1567]

Pseudothrombophlebitis may clinically simulate DVT, thrombophlebitis, rupture of the medial head of gastrocnemius muscle, and intramuscular hematoma. Therefore, these diagnoses may be mixed with each other based solely on the history and clinical findings. Further imaging studies should be performed to discriminate all. Initially, DUS should be performed to rule out DVT. Ultrasound sonography is also a proper imaging modality that has the diagnostic capability in the differential diagnosis. However, MRI provides detailed information with a better demonstration of fluid within calf fascia.[189]

The treatment of pseudothrombophlebitis is supportive. Rest, ice, and nonsteroidal anti-inflammatory drugs are usually sufficient for the recovery. However, if the cyst is copious or there is accompanying hemorrhage during the dissection, compartment pressure may increase to result with compartment syndrome. Hemorrhage is aggravated in patients using anticoagulant similar to our patient. There are two such cases reported in the literature. Petros et al. reported a ruptured Baker's cyst misdiagnosed with DVT, treated with anticoagulation creating hemorrhage and hematoma into the lower extremity compartment.[10] Wilder et al. reported another case that is on the long-term anticoagulation therapy complicated by the development of a posterior compartment syndrome.[11] Both of these cases and our case suggest that anticoagulant may cause bleeding and facilitate the formation of compartment syndrome.

The diagnosis of compartment syndrome necessitates a careful check-up and high degree of suspicion. The extremely tender calf, unexpected pain and/or pain on passive stretching, and hypoesthesia are most important clinical findings. Distal pulses may not be affected. The definitive diagnosis can be done with compartment pressure measurement. Compared to traditional measurement, it is important to obtain the delta pressure (ΔP = diastolic blood pressure minus the compartment pressure), which is thought to better reflect instant tissue perfusion. Any pressure exceeding 30 mmHg indicates compartment syndrome.[12] If the clinical findings are suggestive of compartment syndrome, compartment pressure measurement should be done immediately to confirm or exclude the diagnosis. The treatment is emergent fasciotomy of all involved compartments. The untreated compartment syndrome results with ischemia and necrosis and even total necrosis of the lower limb.

CONCLUSION

Although Baker's cyst rupture and consequent pseudothrombophlebitis are a common clinical condition, compartment syndrome is rare. In the patient using anticoagulant, excessive hemorrhage may cause compartment syndrome in case of cyst rupture. This important clinical clue should be kept in mind and physicians should be aware of compartment syndrome which is an emergent situation. The use of anticoagulants should be particularly questioned and recorded.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

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Conflicts of interest

There are no conflicts of interest.