BACKGROUND: The objective of this investigation is to evaluate the consistency of intra-rater and inter-rater assessments utilizing ultrasound elastography to examine the muscle stiffness of the popliteus and gastrocnemius (medial and lateral heads) in patients with knee osteoarthritis accompanied by myofascial trigger points.
METHODS: Thirty individuals with knee osteoarthritis accompanied by myofascial trigger points were assessed. Two examiners independently measured the muscle stiffness levels of the popliteus and gastrocnemius (medial and lateral heads) three times using ultrasound elastography in the first session. The second session was conducted one week later.
RESULTS: In the initial test session, the mean shear modulus values for the popliteus and gastrocnemius (medial and lateral heads) muscles were measured as follows for tester 1 (12.75, 13.72, 14.13 kPa) and tester 2 (11.66, 12.81, 13.17 kPa). During the retest session, the previously measured variables by tester 1 and tester 2 yielded the following values: (12.61, 13.43, 14.26 kPa) and (11.62, 12.87, 13.30 kPa) respectively.\" Good to excellent intra-rater reliability (ICC = 0.912-0.986) and inter-rater reliability (ICC = 0.766-0.956) were reported for the shear moduli of the popliteus, medial and lateral gastrocnemius muscles.
CONCLUSIONS: The assessment of muscle stiffness in the popliteus and gastrocnemius (medial and lateral heads) using ultrasound elastography is a reliable method in patients with knee osteoarthritis accompanied by myofascial trigger points.

Arthroscopic lateral meniscus repair is performed in the \"figure-of-4 position\" (supine, with the affected knee flexed and the lower leg crossed over the extended contralateral leg), and anchorage is often on the popliteal tendon. Extending the limb at the end of the procedure alters the relations between the popliteal tendon and the repaired meniscus. The present study aimed to assess lateral meniscal suture fixation on the popliteal tendon after a cycle of flexion-extension.
Extending the knee can induce suture release.
Cadaver study.
Twenty-two fresh adult human cadaver knee specimens were used. Under arthroscopy with all-inside implants, a vertical suture onto the popliteal tendon was performed through the lateral meniscus. Suture status was assessed under arthroscopy after a cycle of flexion-extension, and deemed defective if the suture was sufficiently loose for the arthroscope to be able to be passed through the popliteal hiatus, if the stitch had passed through the meniscus, or if the suture was broken.
Thirteen sutures (59.1%) remained well fixed, and 9 (40.1%) were defective: 4 (18.2%) were loose, in 4 (18.2%) the stitch had passed through the meniscus, and in 1 (4.5%) the suture had broken.
In a population of elderly cadaver knee specimens, arthroscopic suture of the lateral meniscus to the popliteal tendon was defective after flexion-extension in 40% of cases. Stress seems to be exerted on the suture when extension is resumed. Thus, a single stitch seems insufficient for stable lateral meniscus repair.
Suture of the lateral meniscus to the popliteal tendon undergoes stress when extension is resumed, potentially causing failure of lateral meniscus repair.
IV.

The popliteus tendon is a useful anchor point to repair the posterior horn of the lateral meniscus. We describe a new, economical technique that does not violate the neurovascular structures, using an antegrade suture passer and a 2-0 fiberwire to repair the posterior segment including posterior horn of the lateral meniscus taking bites through the capsule and meniscus or the popliteus tendon and meniscus with no anchors in the capsule or popliteus. 9 patients were operated upon using this technique and the mean IKDC score improved from 24.2 to 84, p < 0.01, mean pre op Tegner improved from 1.88 to 6.63 p < 0.01, median hop test from 0 to 4, p = 0 at a mean 15.2 months post surgery. 8 patients had a negative Lachman and 1 grade 2 Lachman at 12 months follow up but was asymptomatic. The Barret\'s criteria was negative for all 9 patients at latest follow up.

For iliotibial band (ITB) lateral extra-articular tenodesis or anterolateral ligamentous/capsular reconstruction with anterior cruciate ligament reconstruction, a clear understanding of the referenced anterolateral knee anatomy is critical-especially given the risk of injury to the physis or key anterolateral structures in the paediatric population, which is at high-risk for primary and secondary anterior cruciate ligament injury. The purpose of this study was to quantitatively assess the anatomy of the knee physes, paediatric lateral collateral ligament (LCL) origin, popliteus origin and ITB tibial insertion.
Nine paediatric cadaveric knee specimens with average age 4.2 years (range 2 months-10 years) underwent dissection to identify the LCL\'s and popliteus\' femoral origins and the ITB\'s tibial insertion. Metallic marking pins demarcated precise anatomic attachment sites, and subsequent computerised tomography scans enabled quantified measurements among them.
LCL & Popliteus: On the femur, the popliteus origin lay consistently deep to the LCL and inserted both distally and anteriorly to the LCL, a mean distance of 4.6 mm (range 1.9-7.6; standard deviation 2.0). From the joint line, the LCL lay a mean distance of 12.5 mm proximally while the popliteus measured a mean of 8.2 mm. Both were consistently distal to the physis. The LCL was a mean distance of 4.4 mm (range 1.0-9.5) and the popliteus was a mean distance of 8.2 (range 1.7-12.5) from the physis. ITB insertion: The ITB insertion at Gerdy\'s tubercle had an average footprint measuring 28.2 mm2 (range 10.3-58.4) and the ITB centre lay proximal to the physis in 6 specimens (mean age 4.2 years, median 2.5 years) and distal in 3 specimens (mean age 1.5 years, median 4 months). Mean distance from the footprint centre to the physis was 1.6 mm proximal (range 7.1 proximal - 2.2 distal).
This study describes relative and quantitative positions of the femoral LCL and popliteus origins and tibial ITB attachment and their respective physeal relationships. Knowledge of paediatric anterolateral knee anatomy will help guide essential future research and procedures providing extra-articular anterolateral rotatory stabilisation and may help reduce iatrogenic physeal injury risk.
N/A (descriptive anatomic study).

BACKGROUND: Injuries to the posterolateral corner of the knee are commonly reported in athletes, although the prevalence of isolated injuries to the popliteus in athletes is largely unknown.
OBJECTIVE: To systematically review the literature to better understand the prevalence, mechanisms, sporting activities, tear characteristics, management, outcomes, and return-to-sport rate and timing in athletes who have sustained isolated popliteus injuries.
METHODS: Systematic review; Level of evidence, 4.
METHODS: Following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, the authors searched the PubMed, OVID, MEDLINE, Biosis Previews, SPORTDiscus, PEDRO, and EMBASE databases for studies from January 1988 to August 2021 on athletes who sustained isolated popliteus injuries during sporting activities.
RESULTS: A total of 19 studies consisting of 27 athletes with isolated popliteus injuries sustained during sport were identified. The mean athlete age was 19.9 ± 10.5 years, while 89% (n = 24/27) were male. Traumatic/contact mechanisms were reported in 67% (n = 18/27) of injuries, with American football and soccer being the most common sports. Lateral-sided knee pain was the most frequent complaint, with 85% (n = 23/27) of athletes reporting swelling. Avulsion injuries off the lateral condyle were present in 67% (n = 18/27) of cases. Nonoperative management was performed in 52% (n = 14/27) of athletes. Operative treatment consisted primarily of arthroscopic or open fixation of the osseous fragment. When reported, all athletes successfully returned to sport at a mean of 10.8 ± 8.2 weeks after injury.
CONCLUSIONS: Isolated injuries to the popliteus remain rarely reported in athletes, and athletes are typically evaluated after they experience forced external rotation of the tibia relative to the femur, present with lateral-sided knee pain and effusion, and undergo a stable ligamentous examination. Injuries occurred primarily in male athletes and were the result of traumatic/contact mechanisms, most commonly involving avulsion injuries off the lateral femoral condyle.

Popliteus tendon injuries most often occur in a traumatic setting with damage to multiple other knee structures. Isolated popliteal injuries, however, are rare. To our knowledge, there are no cases of a female pediatric patient with an intrasubstance popliteal tendon rupture in the current literature. This case report aims to illustrate symptoms, imaging, and treatment of an isolated popliteal tendon rupture in an adolescent female. An athletic 14-year-old female presented with right knee pain 4 weeks after a basketball injury in which she dove for the ball and fell, twisting and striking her knee. She had diffuse pain on both sides of the right knee for 3 weeks and pain with running, jumping or twisting. The knee exam was otherwise unremarkable. A right knee MRI demonstrated a complete rupture of the popliteal tendon. No other knee injuries were visualized. The patient was treated non-operatively and gradually returned to normal activities and sports at 6 weeks post injury. On 6-year follow up, the patient had no residual pain or instability and was able to play basketball without difficulty. Isolated popliteal tendon ruptures are extremely rare and difficult to diagnose given non-specific clinical exam findings. While these ruptures can be difficult to visualize on MRI, imaging can help to clarify the diagnosis by ruling out other injuries with similar clinical presentations. In the case of this young and active patient, diagnosis and full recovery without limitations were achieved with 6 weeks of conservative management.

Popliteus is an integral component of the posterolateral corner of the knee. We review the anatomy and various pathologies affecting the popliteus.

BACKGROUND: Injuries of the posterolateral corner (PLC) of the knee lead to chronic lateral and external rotational instability and are often associated with PCL injuries. Numerous surgical techniques for repair and reconstruction of the PLC are established. Recently, several arthroscopic techniques have been published in order to address different degrees of PLC injuries through reconstruction of one or more functional structures. The purpose of this systematic review is to give an overview about arthroscopic techniques of posterolateral corner reconstructions and to evaluate their safeness.
METHODS: A systematic review of the literature on arthroscopic reconstructions of the posterolateral corner of the knee according to the PRISMA guidelines was performed using PubMed MEDLINE and Web of Science Databases on June 15th, 2020. Inclusion criteria were descriptions of surgical techniques to reconstruct different aspects of the posterolateral corner either strictly arthroscopically or minimally-invasive with an arthroscopic assistance.
RESULTS: Arthroscopic techniques differ with regard to the extent of reconstructed units (popliteus tendon, popliteofibular ligament, lateral collateral ligament), surgical approach (transseptal, lateral) and biomechanical results (anatomic vs. non-anatomic reconstruction, restoration of rotational instability and/or lateral instability).
CONCLUSIONS: Different approaches to arthroscopic PLC reconstruction are presented, yet clinical results are scarce. Up to now good and excellent clinical results are reported. No major complications are reported in the literature so far.

OBJECTIVE: There has been a recent resurgence in interest in posterolateral instabilities of the knee joint. As this terminology comprises a large variety of pathologies, confusion and ambiguity in communication between surgeons and allied health professionals are generated. Consequently, accurate classification criteria are required to account for thorough preoperative diagnostics, surgical decision-making, and a standardized scientific documentation of injury severity.
METHODS: A working group of five knee surgeons, who retrospect more than 2000 reconstructions of the posterolateral corner (PLC) at the minimum, was founded. An advanced PubMed search was conducted to identify key definitions. After defining an accurate diagnostic work-up, popular consensus was reached on definitions and covariates for a novel classification, rating of injury severity, and the resulting surgical decision-making.
RESULTS: Three columns (lateral instability, cruciate ligament involvement, and relevant covariates), each ranging from A to D with increasing severity and assigning a number of points, were needed to meet the requirements. The generated terminology translated into the Posterolateral Instability Score (PoLIS) and the added number of points, ranging from 1 to 18, depicted the injury severity score.
CONCLUSIONS: The presented classification may enable an objective assessment and documentation of the injury severity of the inherently complex pathology of injuries to the lateral side of the knee joint.
METHODS: V.

BACKGROUND: Current arthroscopic approaches to the caudal pouches of the lateral femorotibial joint are challenging and risk iatrogenic nerve and cartilage injury.
OBJECTIVE: Describe an alternative arthroscopic approach to the caudal pouches of the lateral femorotibial joint in the horse and report intra-articular abnormalities observed during diagnostic stifle arthroscopy of these pouches.
METHODS: Descriptive cadaver anatomical and clinical study.
METHODS: An approach to the caudal pouches of the lateral femorotibial joint was developed during clinical surgery using an arthroscopic portal in the popliteal tunnel of the femorotibial joint. Relevant anatomy of the lateral femorotibial joint was reviewed and the arthroscopic landmarks validated on 19 cadaver limbs. The procedure was then incorporated as part of routine inspection of 38 joints in 33 horses.
RESULTS: Entry and examination of both pouches of the caudal lateral femorotibial joint was consistently achieved using an arthroscopic portal immediately cranial to the lateral collateral ligament in both cadaver and clinical limbs, with no adverse effects noted in the latter. Contrary to published descriptions, the division of the pouches was principally formed by a meniscopopliteal septum derived from the joint capsule in all cases, rather than the popliteus muscle and tendon as previously described. Abnormalities were detected in five cases. The finding of bilateral tearing within the popliteus muscle may represent a previously unrecognised arthroscopic condition.
UNASSIGNED: Limited case numbers.
CONCLUSIONS: An arthroscopic portal immediately cranial to the lateral collateral ligament permitted consistent entry into the popliteal tunnel and both pouches of the caudal lateral femorotibial joint.