Disorders of the suprapatellar pouch of the knee

Sex-based differences and relationship with the restricted knee flexion angle due to aging: a comparative study

BACKGROUND

The relationship between inferior patellar mobility (IPM) and knee flexion angle has yet to be elucidated. This study aimed to develop quantitative IPM measurement methods and clarify the relationship between IPM and knee flexion angle in community-dwelling older females.

METHODS

This was a cross-sectional study. Overall, 128 healthy older women (age 65-79 years) were recruited from the community to evaluate the relationship between IPM and knee flexion angle. This study was performed between May 2015 and December 2017. The reference value of and sex differences in IPM were evaluated in 205 healthy young adults aged between 19 and 21 years. IPM was compared between healthy older and young women and was objectively measured using our specially designed patellofemoral arthrometer (PFA). Patellar mobility was calculated by normalization to body height. IPM reliability was assessed before all measurements.

RESULTS

Intraclass correlation coefficients for intratester and intertester reliabilities varied from 0.87 to 0.99. The normal range based on two standard deviations of inferior patellar displacement/body height was 5.9-13.5% (young men), 5.1-14.3% (young women), and 1.2-8.8% (older women). IPM was significantly lower in older than young women (P < 0.001). There was a significant positive correlation (r = 0.72 and P < 0.01) between IPM and knee flexion angle in healthy older women unable to flex the knee joint fully.

CONCLUSIONS

Our PFA has good intratester and intertester reliability. The results suggest that IPM decreases with aging in women. IPM and knee flexion angle are correlated among older women unable to flex the knee joint fully.

CLINICAL TRIAL REGISTRATION

Not applicable.

Recurrent Hemarthrosis following Resections of Benign Bone Tumors: A Case Report of Two Pediatric Cases

Introduction/Cases. Two pediatric patients presenting with benign bone tumors of the distal femur at the level of the suprapatellar fat pad developed late onset recurrent knee hemarthrosis following surgical treatment of the lesions. A sinus tract from the intramedullary bone to the knee capsule was discovered in both patients during surgical exploration. Resection of the sinus tract and full closure of the knee capsule resulted in no further recurrence. Conclusion. Postoperative knee effusions in patients following resection near the distal femur could represent hemarthrosis that require additional workup and treatment. Resection of the sinus tract successfully treats the hemarthrosis.

Possible case of pressure resorption associated with osteoarthritis in human skeletal remains from ancient China

Osteoarthritis, one of the most common pathological conditions observed in human skeletal remains, is traditionally thought to only affect the structures within the joint capsule. We examined the osteoarthritic distal femora of an individual from Ancient North China, ca. 475-221 BCE. The standard signs of osteoarthritis, marginal lipping and extensive eburnation, were observed in the patellofemoral compartment of the knee joint. In addition however were bilateral pressure-caused fossae on the extra-articular anterior surfaces of the distal femora 10 mm proximal to the large osteophytes at the apex of the patellar surfaces. Anatomy and possible pathogenesis of knee arthritis are explored in order to come to a tentative aetiology of the extra-articular lesions. These lesions are suggested to be a new criterion for identifying severe knee arthritis. The osteological phenomenon is then placed into archaeological context of the Warring States period of ancient China.

Intraarticular arthrofibrosis of the knee alters patellofemoral contact biomechanics

BACKGROUND

Arthrofibrosis in the suprapatellar pouch and anterior interval can develop after knee injury or surgery, resulting in anterior knee pain. These adhesions have not been biomechanically characterized.

METHODS

The biomechanical effects of adhesions in the suprapatellar pouch and anterior interval during simulated quadriceps muscle contraction from 0 to 90° of knee flexion were assessed. Adhesions of the suprapatellar pouch and anterior interval were hypothesized to alter the patellofemoral contact biomechanics and increase the patellofemoral contact force compared to no adhesions.

RESULTS

Across all flexion angles, suprapatellar adhesions increased the patellofemoral contact force compared to no adhesions by a mean of 80 N. Similarly, anterior interval adhesions increased the contact force by a mean of 36 N. Combined suprapatellar and anterior interval adhesions increased the mean patellofemoral contact force by 120 N. Suprapatellar adhesions resulted in a proximally translated patella from 0 to 60°, and anterior interval adhesions resulted in a distally translated patella at all flexion angles other than 15° (p < 0.05).

CONCLUSIONS

The most important finding in this study was that patellofemoral contact forces were significantly increased by simulated adhesions in the suprapatellar pouch and anterior interval. Anterior knee pain and osteoarthritis may result from an increase in patellofemoral contact force due to patellar and quadriceps tendon adhesions. For these patients, arthroscopic lysis of adhesions may be beneficial.

Nonligamentous Soft Tissue Pathology About the Knee: A Review

Knee pain is one of the most frequent complaints evaluated by orthopedic surgeons. It encompasses a broad range of pathology and can present in a variety of ways. Most of this pain can be attributed to essential structures of the knee, including the menisci, cruciate or collateral ligaments, and articular cartilage. However, there are underrecognized structures in and around the knee that can frequently be a cause of knee pathology and pain. Knee pain stemming from these structures may be missed or incorrectly diagnosed, and these patients often present for second and third opinions because of failure to diagnose and treat the underlying pathology. The synovial plica, suprapatellar pouch, lateral retinaculum, infrapatellar fat pad, and infrapatellar branch of the saphenous nerve are less common but still significant causes of knee pain. Although initial treatment involves various nonoperative modalities, operative treatment is often warranted. Operative and nonoperative management of these soft tissue structures may occur in isolation or with concomitant procedures, including knee ligament reconstruction, total knee arthroplasty, tibial tuberosity osteotomy, or lysis of adhesions. With proper recognition of the role of these structures in knee pain, the orthopedic surgeon can offer a valuable primary or adjunctive treatment option for patients with knee pain, especially those without localizing signs of meniscal, ligamentous, or cartilage damage.

Clinical characteristics of pain originating from intra-articular structures of the knee joint in patients with medial knee osteoarthritis

Purpose

Although disease progression of osteoarthritis has been well documented, pain pathophysiology is largely unknown. This study was designed with two purposes: 1) to characterize patients with knee pain predominantly originating from intra-articular structures and 2) to describe the location and pattern of their pain.

Materials and methods

103 patients with medial knee osteoarthritis underwent an intra-articular injection of local anesthetics (joint block). At least 70% pain relief was defined as positive for the joint block, while less than 50% as negative. Pain characteristics in patients positive for joint block were evaluated in detail using a knee pain map.

Results

Sixty three knees (61%) were positive and 33 knees (32%) were negative. Patients negative for the joint block were significantly higher age, suffered for longer time, and complained more diffuse pain. Although pain at anterior medial area during walk was the most common finding, pain characteristics differed among different knee areas.

Conclusion

The characteristics of joint pain are widely variable even in patients with similar radiological features. Extra-articular sources are not negligible especially in older patients with a long history of diffuse pain. Differences in pain characteristics among knee areas should be taken into account when examining the pain source.

MR imaging of anterior knee pain: a pictorial essay

Anterior knee pathology is a frequent cause of joint pain and limitation of function and mobility among patients presenting to an orthopaedic department. Proper recognition and treatment of pathologic conditions depend on the knowledge of normal anatomy and of the various abnormalities, which affect this area of the knee and may present with anterior knee pain. A broad array of benign and malignant processes may be manifested as anterior knee discomfort, and this common clinical entity is among the most frequent indications for MR imaging of the lower extremities. Clinical history and physical examination are also of paramount importance. The disorders can be categorized and differentiated primarily according to their location. Traumatic or non-traumatic disorders of the patella, patellar retinacula, quadriceps and patellar tendons and supra or infrapatellar fat pad can be the source of symptoms. This article includes a comprehensive pictorial essay of the characteristic MR features of common and uncommon disorders causing anterior knee pain. For accurate assessment of the aforementioned clinical problem, a radiologist should be able to identify typical MR imaging patterns that contribute in establishing the correct diagnosis and thus tailoring the appropriate therapy. Level of evidence IV.

Bilateral lipoma arborescens of the knee: a case report

Lipoma arborescens, a diffuse articular lipomatosis, is a rare disorder characterized by marked villiform synovial proliferation and diffuse replacement of the subsynovial tissue by mature adipocytes. Unilateral joint involvement is the usual presentation while bilateral joint involvement is more uncommon. We reported a case of bilateral lipoma arborescens in a male patient with associated marked patellofemoral osteoarthritis and described the MR imaging findings.