Acute locking in revision total knee arthroplasty due to disengagement of the locking screw

Acute locking of the joint in a replaced knee joint is very rare. This report describes an acute locking episode of a revised modular total knee replacement, occurring more than 2 years after surgery. A disengaged screw from the modular femoral component had lodged in the joint at the inferior pole of the patella and required urgent arthroscopic removal. There was no subsequent failure of the stem–condylar junction, nor loosening of the femoral component.     

An unusual cause of locking

This case report describes the discovery of a plastic foreign body in a patient’s knee joint 21 years from the initial injury. The patient was thoroughly investigated radiologically with plain X-rays both immediately after the initial injury and years later in orthopaedic outpatients. He also subsequently received an MRI. All these were reported as normal. The patient’s symptoms persisted and an arthroscopy was performed. At this procedure the presence of the foreign body was confirmed and the offending plastic was safely removed. The patient’s symptoms of intermittent locking resolved. This experience stresses this importance of clinical suspicion despite apparently normal radiology.     

Bucket-handle meniscal tear in a 5-year-old child

Bucket-handle meniscus tears are a common athletic injury that occur frequently in the adult population but are extremely rare in young children. A 5-year-old male patient presented with left knee pain after a minor fall to the ground. Complaints of pain with full weight-bearing, locking of the joint during walking, a significant limp, 45° flexion contracture of the knee, and an inability to bring the leg into full extension were noted during examination. MRI showed a large bucket-handle medial meniscal tear. The patient made a full recovery after undergoing arthroscopic repair surgery. Level of evidence Case report, Level IV.     

A glass foreign body in the knee joint mistaken for ACL avulsion: an unusual case

Foreign body in the knee is associated with trauma to knee or deliberate self harm. We see them often in clinical practice. They come in all forms and shapes. Very rarely one can find a foreign body within a joint without obvious external scarring (e.g. needle). We have not come across anywhere in the literature of a large foreign body in the knee joint without a definitive history of injury where the external scar has healed so well to become inconspicuous. With this background it is even more difficult when the X-rays mimic anterior cruciate ligament (ACL) avulsion. This case report highlights the fact that diagnosis of a foreign body in the knee joint can sometimes be challenging and almost impossible when there is no history of any injury and when the X-ray mimics ACL avulsion.     

Localized pigmented villonodular synovitis in the anteromedial compartment of the knee associated with cartilage lesions of the medial femoral condyle: report of a case and review of the literature

Localized pigmented villonodular synovitis (PVNS) of the knee is an uncommon entity, presenting with different clinical signs and symptoms. We report on a case of a 42-year-old woman who presented with a 3-year history of knee pain and mechanical problems such as locking. On examination she was found to have a palpable and painful mass over the anteromedial joint line. Magnetic resonance imaging (MRI) revealed a soft tissue mass in the anteromedial compartment of the knee joint. The lesion was completely resected arthroscopically, and histologic examination confirmed the diagnosis of localized PVNS. The patient was free of symptoms, and MRI examination showed no evidence of recurrence at 1-year follow-up.     

Recurrent locking of knee joint caused by intraarticular migration of bioabsorbable tibial interference screw after arthroscopic ACL reconstruction

Two cases are reported in which, after ACL reconstruction with autologous hamstring grafts, tibial polylactide interference screws migrated into the knee joint. Clinically, both patients presented with recurrent locking of the joint. In one case, a broken 15 mm-long tip of the screw was found intra-articularly. In the other case, the whole screw had migrated into the joint cavity. The degradation process of polylactic acid, operative technique and bone quality are discussed as possible reasons for these complications.     

Intra-articular regional migratory osteoporosis of the knee

We report a case of lntra-articular regional migratory osteoporosis of the knee in a 53-year-old man. The case demonstrates an unusual pattern of migration of the marrow edema within the knee joint. This phenomenon has received scant attention in the radiological literature. Received: 9 July 1999 Revision requested: 24 August 1999 Revision received: 6 October 1999 Accepted: 8 October 1999     

Locked knee from superior dislocation of the patella-diagnosis and management of a rare injury

Knee locking is often caused by a torn meniscus or loose body. A rare cause of knee locking is a superior dislocation of the patella following trauma with less than 20 reported cases in the English literature. An unusual case of a locked knee secondary to interlocking osteophytes between the medial femoral condyle and the inferior pole of the patella without any history of trauma is presented.     

Arthroscopic excision of sternoclavicular joint

We report an unusual case of chronic inflammatory arthropathy involving the sternoclavicular joint. Arthroscopic debridement of the sternoclavicular joint cavity was accompanied with the arthroscopic excision of the medial end of clavicle. Twelve months post-surgery the patient is asymptomatic with no signs of recurrence and a full pain free range of movement.     

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. An erratum to this article can be found at     

关节腔内透明质酸钠注射治疗膝关节骨关节炎

目的:探讨骨关节炎关节清理术后透明质酸的疗效。方法:本组26例骨关节炎患者32膝关节,男17例,女9例,平均年龄62岁,左侧18例,右侧14例,治疗前经临床表现、X线和MRI诊断明确,给予行膝关节清理术,术后置管冲洗7~10 d,拔管后给予关节腔注射透明质酸钠,每周一次,共3~5次。结果:随访3~10个月,26例患者32膝关节肿胀消失,疼痛明显减轻,活动度显著改善。结论:关节清理术后持续灌洗加透明质酸钠关节腔内注射能有效治疗骨关节炎。     

A rare patella anatomical abnormality causing locking in an adolescent girl

Locking is an inability to fully extend the knee and is most commonly associated with meniscal pathology and loose bodies. The locked knee is an infrequent presentation in paediatric orthopaedics, and the presence of a patella protuberance as a cause has never been reported in children or adults. An adolescent female presented with a 4-year history of intermittent locking of the right knee associated with a painful audible 'clunk' on full extension. Plain film radiographs and computed tomography showed a posteriorly projecting bony protuberance over the inferior aspect of the patella. The protuberance was removed via an arthrotomy, and the patient made significant improvement in pain and function with no further locking episodes experienced. Level of evidence: IV.     

Baker's cyst. Radionuclide arthrographic findings

Radionuclide arthrography of the knee is described using Tc-99m sulfur colloid, which is injected into the synovial cavity following partial distension of the joint space with saline. The preliminary findings in Baker's cyst are described. There appear to be four patterns: 1) a herniation or cyst that can be posterior, inferior, medial or lateral to the knee synovial space; 2) a limited leak inferiorly toward the calf or superiorly toward the thigh; 3) extensive leak: giant cyst found in patients with rheumatoid arthritis; 4) multiple "cysts" or communications with the knee synovial space. The series is small, and more work is needed before these preliminary findings can be used as firm categories. Radionuclide arthrography should be considered in patients with unexplained calf pain or pain behind the knee, especially with a history of previous internal knee derangement, or rheumatoid arthritis in whom ruptured cysts can closely mimic acute thrombophlebitis. Radionuclide arthrography has certain advantages over contrast arthrography and also arthroscopy in the diagnosis of Baker's cyst.     

Scintigraphic detection of prosthetic joint and soft tissue sepsis secondary to tuberculosis

In a 40-year-old Hispanic woman with pain and swelling in the left knee with a prosthesis, the combination of Ga-67 citrate and Tc-99m methylene diphosphonate (MDP) scans was used to indicate that there was a septic prosthetic joint. At surgery, the joint was infected and a foreign body was found. Cultures positive for tuberculosis were found also. The presence of an incongruent Ga-67 and Tc-99m (MDP) scan pattern suggests infection of the prosthetic joint, as in the following case.     

Bilateral osteochondritis dissecans of the medial trochlea femoris: an unusual case of patellofemoral pain

We report a case of bilateral osteochondritis dissecans of the medial trochlea femoris. Arthroscopic removement of loose bodies in the symptomatic left knee led to an excellent result; the untreated right knee showed effusion and locking one year later. This condition should be considered in the diagnosis of patellofemoral pain.     

Weight loss changed gait kinematics in individuals with obesity and knee pain

BackgroundObesity is a mechanical risk factor for osteoarthritis. In individuals with obesity, knee joint pain is prevalent. Weight loss reduces joint loads, and therefore potentially delays disease progression; however, how the knee joint responds to weight loss in individuals with obesity and knee pain is not clear.Research questionTo assess the effect of weight loss on knee joint kinematics during gait in individuals with obesity and knee pain.MethodsWe recruited individuals with obesity (BMI ≥ 35) and knee pain who were participating in a weight loss program which included bariatric surgery or medical management. At baseline and 1 year follow-up, participants walked on a treadmill, and their knee joint kinematics were assessed using a dual-fluoroscopic imaging system and subject-specific magnetic resonance imaging knee joint models. Gait changes were represented by change in range of tibiofemoral motion, i.e., excursions in flexion-extension, adduction-abduction, internal-external rotation, anterior-posterior translation, medial-lateral translation, and superior-inferior translation during gait.ResultsTwelve individuals with obesity and knee pain completed the gait analysis at baseline and 1 year follow-up. Participants lost on average 10.4% (standard deviation: 17.2%) of their baseline body weight. Reduction in body weight was associated with increased range of flexion-extension (r = -0.75, p < 0.01) and decreased range of adduction-abduction (r = 0.60, p = 0.04) during gait. The reduction in body weight was also associated with self-reported pain decrease (r = 0.62, p = 0.04); however, the change in pain was not significantly associated with kinematic changes.SignificanceWeight loss was associated with improved gait kinematics in the sagittal and frontal planes. The change in gait pattern in individuals with obesity and knee pain was not associated with the change in pain given a reduction in body weight.     

Popliteus tendon tenosynovitis

This case report highlights an unusual cause of anterolateral knee pain. The popliteus muscle arises from three origins--that is, the lateral femoral condyle, the fibula head, and the lateral meniscus--and inserts into the proximal tibia above the soleal line. It may be subjected to a number of pathologies including tenosynovitis, acute calcific tendonitis, rupture, and even avulsion. In this case, the diagnosis of popliteus tendon tenosynovitis was not made from magnetic resonance imaging findings, but was confirmed and successfully treated during arthroscopic examination.     

Foreign bodies.

Foreign bodies are uncommon, but they are important and interesting. Foreign bodies may be ingested, inserted into a body cavity, or deposited into the body by a traumatic or iatrogenic injury. Most ingested foreign bodies pass through the gastrointestinal tract without a problem. Most foreign bodies inserted into a body cavity cause only minor mucosal injury. However, ingested or inserted foreign bodies may cause bowel obstruction or perforation; lead to severe hemorrhage, abscess formation, or septicemia; or undergo distant embolization. Motor vehicle accidents and bullet wounds are common causes of traumatic foreign bodies. Metallic objects, except aluminum, are opaque, and most animal bones and all glass foreign bodies are opaque on radiographs. Most plastic and wooden foreign bodies (cactus thorns, splinters) and most fish bones are not opaque on radiographs. All patients should be thoroughly screened for foreign bodies before undergoing a magnetic resonance imaging study.     

MR imaging of a meniscal ossicle

We report the MR appearance of a meniscal ossicle, which is an unusual etiology for knee pain. The role of MR in differentiating a meniscal ossicle from a loose body is presented. The MR images also demonstrated associated tibial cartilage thinning and a possible meniscal tear. These MR findings led to arthroscopic treatment rather than conservative management. A review of the literature on meniscal ossicles is also presented.     

骨良性纤维病变的影像与病理学分析

目的 提高对骨内良性纤维性病变的影像诊断和鉴别诊断能力. 资料与方法 对96例纤维性骨皮质缺损(FCD)、非骨化性纤维瘤(NOF)、骨化性纤维瘤(OF)和骨纤维异常增殖症(FD)患者的临床、影像学和病理学资料进行比较分析. 结果 FCD和NOF均好发于膝周骨,病理均为无成骨的纤维组织,X线和CT上表现为局限于皮质内和皮质内偏心性膨胀累及髓腔的均匀软组织密度影,MRI上主要为等T1、等T2异常信号.OF和FD病理表现交叉重叠,但OF中成骨细胞镶边现象明显多于FD.OF常见于颅面骨髓腔和胫骨前侧皮质下,表现为单骨内边界清楚的膨胀性不均匀钙质样密度.FD表现为单骨局灶性、弥漫性或多骨囊状膨胀性磨玻璃样改变,MRI上主要为等T1信号,等高混杂T2信号,局灶性FD边缘清楚伴有硬化边,弥漫性FD边界不清. 结论 FCD和NOF因具有相同的好发部位和组织学表现而可将影像学上病变局限于骨皮质者视为FCD,膨胀侵及髓腔者视为NOF.OF和FD的影像学鉴别点在于病变部位、边界和累及范围.