Posterolateral Knee Pain Research Articles

Lateral Femoral Condyle Stress Fracture in an Ultramarathoner: A Case Report.

A 62-year-old ultramarathon athlete presented to the clinic with right posterolateral knee pain for 3 to 4 weeks and muscle tightness. Magnetic resonance imaging demonstrated a right lateral femoral condyle fracture. The fracture was treated conservatively, with return full Ironman competition 14 months later. Femoral condyle fractures should be suspected in endurance athletes with nonspecific knee pain to prevent further injury. These fractures are rare, and more studies are needed to determine risk factors, risk classification, and optimal treatment protocol. With rising popularity of ultraendurance events, sports medicine physicians must educate patients on injury recognition and mitigation strategies.

X-ray Imaging Versus Anatomical Dissection for Identification of the Fabella.

Reported prevalence rates of the fabella sesamoid bone vary widely, particularly between studies based on either X-ray imaging or anatomical dissection approaches. The purpose of this study was to directly compare these two methodologies in their detection of fabellae and investigate whether variability in the density of fabellae could explain any discrepancies. Fifty cadaveric knee segments were examined for the presence of a fabella by both X-ray imaging and anatomical dissection. The relative density of each excised fabella specimen was then quantified using a separate set of radiographs. Results: Fabellae were detected in 40% of the sample knees via a manual dissection approachbut in just 12% of those same specimens using X-ray imaging. Relative density measurements confirmed that fabellae identifiable only via dissection were significantly less dense than fabellae visible in whole knee radiographsbut denser than the surrounding tissue. Radiology cannot reliably detect cartilaginous or incompletely ossified fabellae, which were found in 28% of the study population. Clinicians should consider the potential occurrence of a fabella when diagnosing posterolateral knee pain, even if it may not be visible via X-ray.

Fabella fracture: An uncommon cause of posterolateral knee pain: Case report

Fabella fracture: An uncommon cause of posterolateral knee pain: Case report

Deep Infection After Anterior Cruciate Ligament Reconstruction Diagnosed by Intratunnel Suspensory Fixation Device Migration: A Case Report.

A 43-year-old woman sustained an anterior cruciate ligament injury while kickboxing and underwent anterior cruciate ligament reconstruction with hamstring autograft with suspensory fixation. Lateral thigh wound was superficially infected at 2 weeks postoperatively with resolution of signs and symptoms after debridement. Three months later, posterolateral knee pain developed and radiographs revealed intratunnel migration of the device. That observation with abnormal magnetic resonance imaging and serology results led to the diagnosis of deep infection. Immediate device removal and debridement were performed. Consequently, the grafts were preserved, and the patient could perform kickboxing 2 years thereafter. Intratunnel migration of suspensory fixation devices can support a diagnosis of infection.

Arthroscopic popliteal tenotomy grants satisfactory outcomes in total knee arthroplasty with persistent localised posterolateral pain and popliteus tendon impingement.

The purpose was to estimate the prevalence of popliteus tendon impingement following TKA, and to describe the characteristics and the differential diagnosis protocol for this rare condition. The hypothesis was that arthroscopic popliteal tenotomy in TKA patients with suspected popliteus tendon impingement would relieve pain and improve satisfaction. Of 741 TKAs performed over three years, eight (1.1%, all women) had suspected popliteus tendon impingement, of which seven had severe localised posterolateral knee pain and one global knee pain. Upon confirmation of popliteus tendon impingement, arthroscopic popliteal tenotomy was performed, and outcomes (Pain on visual analogue scale (pVAS; best, 0; worst, 10), Oxford Knee Score (OKS; best, 48; worst, 0) and satisfaction (best, 100%; worst, 0%) assessed at mean 18-month follow-up. At four to 30months after TKA, arthroscopic exploration revealed popliteus tendon impingement in all eight knees. Six reported complete pain relief (pVAS, 0) the day following arthroscopic popliteal tenotomy, whilst one reported some residual pain (pVAS, 2). The remaining patient with global pain reported no pain relief, and required revision TKA at 12months. Excluding the revised TKA, OKS was between 19 and 43, and satisfaction was rated ≥ 80% in five of the remaining seven patients. Arthroscopic popliteal tenotomy relieved symptoms in TKA patients with persistentlocalised posterolateral pain and a positive popliteus test. These findings suggest that the popliteus test is reliable to diagnose popliteus tendon impingement following TKA, which could be treated by arthroscopic popliteal tenotomy. Level IV, Small case series.

Fabella Syndrome of Bilateral Knee with Common Peroneal Nerve Compression Neuropathy

Fabella syndrome is a rare, often underdiagnosed cause of recurrent posterolateral knee pain. It can disrupt the common peroneal nerve because of its anatomical location at the lateral head of the gastrocnemius at the lateral femoral condyle, where the nerve typically passes. Far East Asians have been shown to have a higher prevalence of fabella syndrome attributed to their genetic predisposition combined with mechanical causes. Failure to adequately identify a common peroneal nerve neuropathy associated with fabella syndrome can lead to recurrent visits, unnecessary examinations, and surgical procedures. Here, we present a case of a patient presenting with recurrent posterolateral knee pain and a slapping gait. Therefore, a high index of suspicion for fabella syndrome is warranted by a physician to diagnose this condition for the best outcome for the patient.

Fabella Syndrome of Bilateral Knee with Common Peroneal Nerve Compression Neuropathy

Fabella syndrome is a rare, often underdiagnosed cause of recurrent posterolateral knee pain. It can disrupt the common peroneal nerve because of its anatomical location at the lateral head of the gastrocnemius at the lateral femoral condyle, where the nerve typically passes. Far East Asians have been shown to have a higher prevalence of fabella syndrome attributed to their genetic predisposition combined with mechanical causes. Failure to adequately identify a common peroneal nerve neuropathy associated with fabella syndrome can lead to recurrent visits, unnecessary examinations, and surgical procedures. Here, we present a case of a patient presenting with recurrent posterolateral knee pain and a slapping gait. Therefore, a high index of suspicion for fabella syndrome is warranted by a physician to diagnose this condition for the best outcome for the patient.

Sonographic Diagnosis and Treatment of Fabella Syndrome: A Neglected Posterolateral Knee Pain.

Sonographic Diagnosis and Treatment of Fabella Syndrome: A Neglected Posterolateral Knee Pain.

Popliteus Tendon Injuries.

Popliteus tendinopathies are rare injuries that can occur from overuse, trauma, or secondary causes, such as sesamoid bones or calcifications. They present with nonspecific symptoms and should be considered in any patient with posterolateral knee pain, instability, popliteus tenderness, and a positive Garrick test. Diagnosis can be made with magnetic resonance imaging, but arthroscopy remains the criterion standard. For minor popliteus tendinopathies, initial management involves conservative treatment, including rest, activity modification, physical therapy, and quadriceps strengthening. For more severe or refractory disease, corticosteroid injections and arthroscopy should be considered. [Orthopedics. 2023;46(4):e193-e198.].

Effectiveness of X‐ray in Detecting the Fabella Sesamoid Bone

The highly variable prevalence of the fabella, a sesamoid bone located posterior to the lateral condyle of the femur, invites further investigation. A recent meta‐analysis by Berthaume [J. Anat. 2019 Jul; 235(1): 67‐79. doi:10.1111/joa.12994] reports that the incidence rate of the fabella has increased over the past 150 years. Within the data aggregated by that study, there is also a significant difference in detecting the fabella based on the method of detection ‐ anatomical dissection (28.9% prevalence, N = 5723 knees) vs. X‐ray (15.3% prevalence, N = 13665 knees). We sought to investigate whether variation in the density of fabellae could explain both changes in its prevalence over time as well as the discrepancy between methodologies.Our first aim was to directly compare the two methodologies, dissection and X‐ray, within the same set of knees on their determination of fabella prevalence. We hypothesized that fewer fabellae would be detected by X‐ray than dissection. Secondarily we are currently evaluating the hypothesis that some fabellae exist but are not sufficiently dense to be reliably detected via X‐ray.Fifty human knees were isolated by transverse sections through the middle of the upper and lower legs. The knees were obtained from cadavers received through the Saint Louis University Gift Body Program of the Center for Anatomical Science and Education (CASE) with signed, informed consent from the donor. The CASE Gift Body Program abides by all the rules set forth by the Uniform Anatomical Gift Act. An X‐ray generator (AJEX Meditech) emitted rays at 70 kV, 2.0 mAs through the medial or lateral side of each knee into a photo‐sensitive plate. Images from the plate were digitized using TigerView software. Three raters assessed whether a fabella was present in the X‐ray images (e.g. Fig. 1) using inter‐rater agreement, while one individual subsequently performed anatomical dissection.The prevalence rate via X‐ray was 12% (using a standard of 2/3 rater agreement). Fleiss’ kappa was 0.24 for X‐ray ratings, which represents a fair amount of interrater agreement. The prevalence rate based on anatomical dissection was 54%, which is significantly different from that of X‐ray (p < .0001, chi‐square statistic is 19.95).These results confirm that X‐ray imaging underreports the prevalence of fabellae. This is to our knowledge the first study that directly compares X‐ray against dissection within the same subjects for sesamoid identification, which is important for diagnosing conditions such as fabella syndrome on presentation of posterolateral knee pain. The authors continue to analyze the fabellae obtained from anatomical dissection to determine why some sesamoids are not consistently visible under X‐ray.

Open Excision of a Painful Fabella

Fabella syndrome is a relatively rare but potentially debilitating condition that causes posterolateral knee pain and swelling, as well as issues with flexion and/or extension of the knee. Irritation, pain, and cartilage damage ensue as the capsule and fabella make contact with the posterior lateral femoral condyle. This condition should be considered in cases of posterolateral knee pain in which other more common pathologies are not readily identified and when patients present with a positive finding of tenderness on examination at the fabella. Initial treatment consists of activity modification and rest, physical therapy, and potentially cortisone injections. When these fail, surgical excision of the fabella should be considered. Surgery in the posterolateral knee, however, requires careful consideration of the immediate and surrounding anatomic structures and arthroscopy, which can be technically challenging. The objective of this technical note is to describe our open technique for symptomatic fabella excision that is easily reproducible, with pearls to minimize risk to the posterolateral structures of the knee.

Fabella syndrome in a professional football player: A case report and literature review.

Introduction and importanceFabella syndrome is a rare cause of posterolateral knee pain. The definitive diagnosis and management of this syndrome remain unclear.Case presentationWe report a case of a 19-year-old patient who is a Vietnamese professional football player. He presented with persistent pain in the posterolateral aspect of the knee joint for 12 months that was unrelated to trauma. He was treated conservatively for 6 months without any improvement in the previous hospital. He was diagnosed with fabella syndrome and underwent open surgery to remove the bone. Evaluation after surgery 12 weeks revealed the symptoms disappeared and he was able to return to practice.Clinical discussionIn order to diagnose fabella syndrome, the clinicians need to be vigilant and base on the clinical signs as well as imaging to exclude other causes of posterolateral knee pain. Conservative therapy is always the first choice of treatment although the recurrence rate is high, especially in professional athletes. If the initial conservative therapies failed, the fabella surgical removal surgery should be made in athletes.ConclusionFabella syndrome is a rare cause of posterolateral knee pain in professional athletes. The definitive diagnosis and management of this syndrome remain unclear. Our case shows that surgical removal of the bone fragments can be considered if failure after the initial conservative therapies.

Treatment of Fabella syndrome with arthroscopic fabellectomy: a case series and literature review

BackgroundThe fabella is a sesamoid bone in the posterolateral capsule of the human knee joint. In quadrupedal mammals, the fabella is believed to have a role similar to the patella in redirecting extension forces of the knee joint from one point to another. In bipeds, the fabella is not touching the back of the bent knee, and therefore the role in redirecting forces declines. Posterolateral knee pain can be associated with the irritation between the fabella and lateral femoral condyle, a phenomenon also known as fabella syndrome. In cases that are unresponsive to conservative management, surgical fabellectomy can be a successful treatment option. Among the surgical approaches, open resection is most commonly seen. There are also literature reporting arthroscopic-assisted open resection, but seldom mentioned the all-arthroscopic fabellectomy.Case presentationWe present 3 patients with a long history (> 12 month) of posterolateral knee pain under suspicion of different pain origins. The diagnosis of fabella impingement was eventually made by ruling out of other causes. All the patients underwent all-arthroscopic fabellectomy for diagnosis and treatment. Investigations of the resected fabella suggested chronic impingement with apparent osteophyte formation and cartilage wearing of the articular side. All patients have been continually followed up at our outpatient department and reported to be pain free after the procedure.ConclusionsIn the patients presenting posterolateral pain, fabella syndrome cannot be ignored due to its relative higher presence in Asian population. In our experience, the all-arthroscopic fabellectomy offers a smaller wound size, less post-operative pain, fewer days of hospitalization and quicker time to rehabilitation for the patients with chronic posterolateral knee pain caused by fabella syndrome.

Characterization of mononeuropathy of the lateral cutaneous nerve of the calf.

Isolated injuries to the lateral cutaneous nerve of the calf (LCNC) branch of the common peroneal nerve can cause obscure chronic posterolateral knee and upper calf pain and sensory symptoms. Routine examination and electrodiagnostic testing do not detect them because the LCNC has no motor distribution and it is not interrogated by the typical peroneal nerve conduction study. There are only about 10 prior cases, thus scant physician awareness, so most LCNC injuries remain misdiagnosed or undiagnosed, hindering care. We extracted pertinent records from seven patients with unexplained posterolateral knee/calf pain, six labeled as complex regional pain syndrome, to investigate for mononeuropathies. Patients were asked to outline their skin area with abnormal responses to pin self-examination independently. Three underwent an LCNC-specific electrodiagnostic study, and two had skin-biopsy epidermal innervation measured. Cadaver dissection of the posterior knee nerves helped identify potential entrapment sites. Initiating events included knee surgery (three), bracing (one), extensive kneeling (one), and other knee trauma. All pin-outlines included the published LCNC neurotome. One oftwo LCNC-specific electrodiagnostic studies revealed unilaterally absent potentials. Longitudinal, controlled skin biopsies documented profound LCNC-neurotome denervation then re-innervation contemporaneous with symptom recovery. Cadaver dissection identified the LCNC traversing through the dense fascia of the proximolateral gastrocnemius muscle insertion. Isolated LCNC mononeuropathy can cause unexplained posterolateral knee/calf pain syndromes. This series characterizes presentations and supports patient pin-mappings as a sensitive, globally available, low-cost diagnostic aid. Improved recognition may facilitate more rapid, accurate diagnosis and, thus, optimize management and improve outcomes.

A rare etiology of posterolateral pain subsequent to a total knee arthroplasty

This case report illustrates a very rare problematic after Total Knee Arthro-plasty (TKA), yet that you have to think of if posterolateral pain appears. The postoperative outcome of our patient was initially very good, but pain appeared after 6 weeks, in an atypical mode, that couldn’t be attributed to the most common differential diagnosis. The characteristics of the symptoms directed us to a mechanical cause and the solution finally came up by means of a radiography: the images showed an impingement between one of the tibial tuberosity fixation screw’s head and the fibular neck. What couldn’t be seen on the primary images was an irritating callus, that was detected at 3 months postoperatively. The pain disappeared after surgical removal of the screw. Keywords: Total knee arthroplasty; Posterolateral knee pain; Pain after total knee ar-throplasty; Tibial screw impingement.

Relationship between fabella and posterolateral knee pain and common peroneal nerve injury

To analyze the incidence and characteristics of fabella in the Chinese population and its correlation with pain in the posterolateral region of the knee joint and common peroneal nerve palsy. Total 732 patients including 405 males(450 knees) and 327 females(383 knees) who underwent unilateral or bilateral knee MR imaging from September 2015 to July 2019 were retrospectively evaluated. The basic information of all patients was extracted from the hospital's his system. The patient's medical records were checked by telephone follow-up or his system, and the number of patients with posterolateral knee pain and common peroneal nerve paralysis were recorded. The overall prevalence of fabella was 48.38%, 23.53% in men and 24.85% in women, there was no significant difference between them (P>0.05). All the subjects were divided into five age groups. The prevalence of fabella was significantly different among different age groups:6.6% in 20 year-old group, 33.8% in 21 to 34-year-old group, 53.5% in 35 to 44-year-old group, 57.5% in 45 to 59-year-old group and 73.9% in ≥ 60-year-old group, the difference was statistically significant (P<0.001). There was a significant correlation between the prevalence of fabella and the age of patients. With the increase of patients' age, the prevalence of fabella in knee joint also showed an obvious upward trend (P<0.001). According to the presence of fabella in the knee joint, 232 cases of knee joint pain were found, accounting for 57.57% of the patients with fabella, accounting for 27.85% of the total data(P<0.01). The correlation score analysis was R=1.546, P<0.01;when the presence of fabella in the knee joint, a total of 44 cases of common peroneal nerve paralysis occurred in the knee joint, accounting for all knees 28% of the total knee joint, and 29 cases of common peroneal nerve palsy (3.48% of the total knee joint) were found when there was no fabella in the knee joint(P<0.05). The correlation score analysis was performed with R=1.695, P<0.05. The prevalence of fabella us in Chinese population is 48.38%. There is no relationship between the incidence of gastrocnemius and gender, but the incidence of fabella is positively correlated with age, pain in the posterolateral region of the knee joint and the occurrence of common peroneal nerve symptoms.

Prevalence of the fabella and its association with pain in the posterolateral corner of the knee: A cross-sectional study in a Romanian population.

The functions and clinical consequences of the fabella, a sesamoid bone found in the posterolateral aspect of the knee joint, are still a reason of intense debate in the scientific literature. Its incidence was reported to range between 20% and 87% and its presence was usually associated with the persistent pain in the posterolateral region of the knee. The aim of our study was to measure the prevalence, anatomic and clinical features of the fabella within a cross-sectional study, conducted in a Romanian orthopaedic center. Between 2015 and 2017, a consecutive series of 562 patients with knee injuries or persistent knee pain has been examined by radiographs and Magnetic Resonance Imaging and a set of anatomical and clinical parameters have been recorded. Collected data was evaluated with RadiANT DICOM Viewer and statistically analyzed with GraphPad Prism 7. The level of significance was set at P <.05. The incidence of the fabella in our study group was 16.93%, lower than previously reported for Caucasian populations. We found statistically significant differences regarding the possible association of the fabella with pain in the posterolateral corner of the knee (P = .04) and the 2 dimensions of the bone according to gender (P = .03 respectively P = .01), but the prevalence was not influenced by gender (P = .6). The anatomic characteristics could be important in differentiating this sesamoid bone from calcifications or loose bodies located in the knee joint region. Due to the high association with the posterolateral knee pain, the fabella should be recorded during knee examination as a differential diagnosis, before any surgical procedure.

Fabella Syndrome Following De-Rotation Surgery to Correct a Femoral Malunion

Background:The fabella is a sesamoid bone situated within the lateral head of the gastrocnemius tendon, close to the lateral femoral condyle, and adjoined to the fabellofibular ligament. It is a normal variant, found in up to 87% of patients. Fabella Syndrome describes traditionally posterolateral knee pain, occurring due to biomechanical pressure of the fabella against the lateral femoral condyle. Given its rarity, its diagnosis is often overlooked. We present a case of Fabella Syndrome with a modified surgical excision technique and review of the literature.Methods and Results:A thirty-four-year-old man presented with posterolateral knee pain following de-rotation surgery to correct a femoral malunion, from a previous femoral shaft fracture. Due to the patient’s complex orthopaedic history, Fabella Syndrome was not initially diagnosed. Fabellectomy eliminated all symptoms of knee pain, with no limitations in knee function.Conclusion:Review of the literature identified ten publications (evidence level IV) describing Fabella Syndrome. This is the first reported case of Fabella Syndrome secondary to femoral de-rotation surgery. The authors recommend fabellectomy as a definitive treatment for Fabella Syndrome, in keeping with published literature.

Diagnosing and Treating Popliteal Tendinopathy After Total Knee Arthroplasty

The following office tip describes four patients that underwent primary total knee arthroplasty and developed posterolateral knee pain at a mean follow-up duration of 1.6 months postoperatively. The first patient in this series noted substantial pain lying in bed (in a lateral decubitus position with the operative leg up) while attempting to abduct her leg to adjust her sheet in bed. A thorough clinical and radiographic work-up was performed. This patient’s posturing in bed (and subsequent physical exam maneuver) led to a presumptive diagnosis of popliteal tendinopathy. The diagnosis was confirmed arthroscopically by identifying a frayed and inflamed popliteal tendon. After undergoing arthroscopic popliteal tendon release, the patient noted complete pain relief while retaining coronal stability in both flexion and extension. The following office tip defines a previously undescribed clinical diagnostic examination for popliteal tendinopathy that was identified based on a patient’s symptomatology and subsequently utilized to identify three additional cases of arthroscopically confirmed popliteal tendinopathy.

Arthroscopy-Assisted Fabella Excision: Surgical Technique

The fabella is an anatomic variant not seen in all individuals and can potentially be a source of chronic knee pain due to chondromalacia, osteoarthritis, fractures, or biomechanical pressure against the lateral femoral condyle. It is situated intra-articular, close to the lateral femoral condyle, the lateral gastrocnemius head tendon, and the fabellofibular ligament. Given its rarity, the diagnosis of a symptomatic fabella is often overlooked when evaluating patients with persistent posterolateral knee pain. However, this diagnosis should always be considered, especially in high-performance runners, bikers, and triathletes. Although nonoperative management can potentially resolve symptoms associated with this condition, fabella excision via arthroscopically assisted surgery is a reliable and safe alternative to treat patients who do not benefit from nonsurgical treatment. We present our technique detailing fabella excision for treatment of posterolateral knee pain, which includes an arthroscopic evaluation of the fabella to assess damage to the femoral condyle and minimize over-resection and potential damage to surrounding structures.