UNASSIGNED: Many studies have shown that injury to the popliteus tendon has little consequence for the static stability of the knee following total knee arthroplasty (TKA). However, very few studies have evaluated the effect of intraoperative iatrogenic popliteus tendon injury on the patient-reported outcome measures (PROMs) following TKA. This study aimed to determine the incidence of iatrogenic popliteus tendon injury in our subset of the population and to find out its effect on PROMs.
UNASSIGNED: 100 consecutive osteoarthritic varus knees with flexion deformities less than 20° were operated upon by a single senior experienced arthroplasty surgeon. Patients were assessed intraoperatively for any iatrogenic popliteus tendon injury, the injury site, and the amount of injury which was quantified and graded. PROMs applied for assessment at 1-year follow-up were Knee Society Score (KSS 1), Knee Function Score (KSS 2), and Western Ontario and McMaster University Osteoarthritis Index (WOMAC).
UNASSIGNED: 17% of cases had an iatrogenic popliteus tendon injury. Thirteen had grade II injuries, whereas four had grade III injuries. There was no statistical significance in post-operative knee mobility and PROMs among those with popliteus tendon injury versus non-injured patients.
UNASSIGNED: The incidence of iatrogenic popliteus tendon injury is higher than what we expected. The tendon injury remains a risk, but it is unclear how the popliteus tendon injury will affect patients after the TKA. In our series, such an injury during knee replacement does not affect the functioning of the knee in the short term; however, a long-term follow-up is warranted.

UNASSIGNED: Drilling the tibial tunnel in tibiofibular-based posterolateral corner (PLC) reconstructions is usually performed with a starting point from Gerdy\'s tubercle. Drilling the tunnel starting from the anteromedial tibial cortex could reduce the risk of popliteal neurovascular (PNV) injury. The purpose of this study is to assess the distance on Magnetic Resonance Imaging Scans (MRI) of the PNV bundle and peroneal nerve (PN) to these two different tunnel trajectories.
UNASSIGNED: A total of 87 MRI scans were assessed. The ideal exit point of the tibial tunnel in PLC reconstructions was marked. We added 10 mm from this point in a straight posterior and in an oblique trajectory, mimicking the two different tunnel trajectories and measured the distance to the PNV bundle and PN from these two points.
UNASSIGNED: The mean distance of the tip of the guide wire drilled with a trajectory from Gerdy\'s tubercle to the PNV bundle and the peroneal nerve was respectively 13.2 mm (SD = 3.96) and 17.7 mm (SD = 4.39). The mean distance of the tip of the guide wire drilled with a trajectory from the anteromedial tibial cortex to the PNV bundle and the PN was respectively 19.6 mm (SD = 4.19) and 12.2 mm (SD = 3.96).). Drilling in a trajectory from the anteromedial tibial cortex significantly increases the distance to the PNV bundle (p < 0.001).
UNASSIGNED: Tibial tunnel drilling in a tibiofibular based PLC reconstruction from the anteromedial tibial cortex significantly increases the distance to the popliteal artery but with a decreased distance to the peroneal nerve.
UNASSIGNED: level IV.

Introduction During total knee arthroplasty (TKA), also referred to as total knee replacement (TKR), patients may experience pain in the posterolateral knee. One possible cause is the impingement between the popliteus tendon and the femoral components. The purpose of this study was to analyze the posterolateral overhang of the femoral component using 3D template software. Methods Preoperative CT scan images of 50 knees (11 males and 39 females) with osteoarthritis of grade 2 or lower according to the Kellgren-Lawrence classification were analyzed. The mean age of the subjects was 73.8±7.6 years (range 52-84 years). The Athena (Soft Cube Co., Ltd., Osaka, Japan) knee 3D image-matching software was used for the analysis. The positions of the two femoral components (symmetrical and asymmetrical) were simulated. In the coronal plane, the component overhang was measured between the resected lateral part of the posterior femur and its corresponding component size, and the two designs were compared in three zones (proximal, central, and distal). Results In the simulated femoral component, the asymmetric design had a significantly lower component overhang than the symmetric design in the proximal zone of the lateral posterior condyle (0.2±1.9 mm vs. 3.5±1.6 mm, p<0.01). In the proximal zone, significant overhang (>3 mm) was observed in 30 knees (60.0%) with the symmetric design, but only three knees (6.0%) had asymmetric designs (p<0.01). Conclusions The posterolateral overhang of the lateral posterior condyle occurs when a symmetrical prosthesis is used. The use of an asymmetric implant with a small, rounded proximal portion of the lateral posterior condyle improves this overhang and is expected to decrease problems such as impingement of the popliteus tendon and improve patient satisfaction.

The posterolateral region of the knee has a complex and diverse anatomy. Hydrarthrosis of the knee can potentially communicate with other parts of the joint space. The joint fluid distribution reflects anatomical communications between synovial spaces. To observe the continuity between the knee joint cavity and the surrounding bursa, we devised a dissection method with a new injection agent, an eosin-containing congealed liquid that spreads uniformly over the entire space. The purpose of this study was to perform a detailed examination of the subpopliteal recess (SPR) where a bursa connects to the knee joint capsule. We also reported the advantages of this new injection agent compared with conventional materials (latex and epoxy resin). Twenty-two formalin-fixed cadavers (34 knees), two N-vinyl-pyrrolidone (NVP)-fixed cadavers (4 knees), and two cadavers (3 knees) fixed by Thiel\'s method were used. After filling the knee joint space and SPR with eosin congealed liquid, the specimens were dissected to investigate the morphology of the SPR. In addition, three different types of injection agents were assessed. The SPR extended distally along the popliteus tendon. The SPR length was 22.64 ± 11.38 mm from the upper end of the lateral tibial condyle to the lower end of the depression. The existence of a fabellofibular ligament made the SPR significantly longer, but abrasion of the femoral articular cartilage did not affect the SPR. Furthermore, the relationship between the popliteus muscle and the SPR was classified into three types (types 1-3). Types 2 and 3 in which the SPR extended to the proximal tibiofibular joint may cause instability of the knee joint. The eosin congealed liquid was highly useful in many aspects, such as fluidity and injection workability. The new dissection method with eosin congealed liquid provides insights into the anatomy of the posterior lateral knee, which are useful for radiological diagnoses and clinical treatments.

OBJECTIVE: To review and update the literature regarding outcomes following surgical management of chronic, grade III posterolateral corner (PLC) injuries, with an emphasis on estimating failure rates based upon objective parameters in light of the 2019 expert consensus, while secondarily comparing the failure rates of anatomic versus non-anatomic reconstruction techniques.
METHODS: A literature search was performed using the PubMed, Embase, MEDLINE, and Cochrane Library databases. Inclusion criteria consisted of level I-IV human clinical studies reporting subjective and objective outcomes in patients following surgical management for chronic (>6 weeks from injury) grade III PLC injuries, with a minimum two-year follow-up. The criterion for objective surgical failure was based on post-operative varus stress radiographs and defined as a side-to-side difference of 3 ​mm or more of lateral gapping.
RESULTS: A total of six studies, consisting of 10 separate cohorts encompassing a total of 230 patients, were identified. PLC reconstruction was performed in all cohorts, with 80 ​% (n ​= ​8/10) of these cohorts utilising an anatomic reconstruction technique. A failure rate ranging from 4.3 ​% to 36 ​% was found. Subgroup analysis revealed a failure rate of 4.3 ​%-24.2 ​% for anatomic reconstruction techniques, whereas a 0 ​%-36 ​% failure rate was found for non-anatomic reconstruction. Arthrofibrosis was the most common complication (range, 0 ​%-12.1 ​%) following surgery. 0 ​%-8 ​% of patients required revision PLC surgery.
CONCLUSIONS: PLC reconstruction yields a wide variability in failure rates according to the side-to-side difference of 3 ​mm or more of lateral gapping on post-operative varus stress radiographs, with low revision rates following anatomic and non-anatomic reconstruction techniques.
METHODS: IV; Systematic Review of Level III and IV studies.

The acute locked knee is a common presentation of meniscal tears or other intra-articular injuries. However, a popliteus tendon tear, an uncommon cause of acute locked knee, is often overlooked as a possible diagnosis. Here, we present the case of a 29-year-old male who experienced an acute locked knee following a sports injury. An arthroscopic examination revealed an intrasubstance tear in the popliteus tendon and a complete anterior cruciate ligament tear, while the menisci remained intact. Due to the extension lag caused by the popliteus tendon tear, the anterior cruciate ligament reconstruction was postponed. The patient then underwent a course of physiotherapy before the anterior cruciate ligament reconstruction and eventually achieved full knee extension after six weeks. Further surgical intervention was then performed to address the ligament injury. Our case highlights the importance of considering a popliteus tendon tear as a possible cause of an acute locked knee. Proper diagnosis and management are crucial for achieving optimal outcomes for patients with an acute locked knee and concomitant ligamentous injury.

OBJECTIVE: The objectives of this prospective study were to evaluate the risk of peroneal nerve (PN) injury in simulated all-inside lateral meniscal repair with sutures placed through the popliteus tendon (PT) and to determine the optimal needle length.
METHODS: Twenty-nine axial magnetic resonance images (MRI) of postoperative knees with infused intra-articular fluid and in a figure-of-four position were used. The cross-sectional length of the PT was divided into four equal parts with measurements performed at the 25%, 50% and 75% points according to their anteroposterior arrangement. Simulated repairs were performed with 14-mm and 18-mm straight needles via the anteromedial (AM) and anterolateral (AL) portals. Distances from the needle tip following full insertion through the PT to the PN and from the anterior PT border to the posterior knee capsule were measured to determine PN injury risk and ideal needle insertion depths at the different landmarks.
RESULTS: Simulated repairs on the 29 knee MRI images resulted in no incidences of PN injury. The average distances from the needle tip to the PN of the 14-mm needle were significantly greater than the 18-mm needle in all the simulated repairs (P < 0.02), except at the 25% point in the AM approach. When using the 14-mm needle, capsule underpenetration was found in three knees (10.3%) at the 25% point during the AM approach, in one knee (3.4%) at the 50% and 75% points in the AM approach, and in all repairs from the AL portal. The average distances from the anterior PT border to the capsule at the 25%, 50%, and 75% division points on the PT in the AM approach were 7.7 ± 2.7 mm, 7.9 ± 2.5 mm and 7.6 ± 2.8 mm, respectively, whilst in the AL approach were 8.4 ± 2.9 mm, 8.1 ± 2.8 mm and 7.6 ± 2.7 mm.
CONCLUSIONS: Simulated all-inside lateral meniscal repair with suture placement through the PT with 14-mm and 18-mm needles was safe. The measurements in this study can be used to determine potential PN injury risk in relation to the PT and the appropriate needle length for safe lateral meniscal repairs.

UNASSIGNED: Injuries to posterolateral corner (PLC) of knee are often neglected. The three key components of PLC are lateral collateral ligament (LCL), popliteofibular ligament (PFL) and popliteus tendon (PT). For adequate reconstruction, anatomic location of these ligaments should be well understood.
UNASSIGNED: Twenty formalin fixed cadaveric knees were dissected. PT and LCL identified. Circumference of the two structures marked with pen just after cutting them close to bone surface. Distance between the centre of LCL and PT was measured along with the measurement of distal femoral medio-lateral dimension (MLD) and Anteroposterior dimension (ALD) of lateral condyle.
UNASSIGNED: The mean distance between PT and LCL measured in 20 specimens was 8.3 ± 0.84 mm, with a range of 7 mm to 10 mm. MLD was 81.0 ± 3.6 mm and APD was 62.7 ± 3.2 mm.
UNASSIGNED: The distance in Indian population is significantly smaller compared to the western. This has clinical implication in drilling the tunnels for PLC reconstruction.

UNASSIGNED: This study aimed to evaluate the effect of arthroscopic treatment of popliteus tendinitis via an auxiliary extreme lateral approach and to investigate the pathogenesis and treatment of popliteus tendinitis.
UNASSIGNED: From 2016 to 2020, arthroscopic popliteus tendon ablation was performed in 15 patients (15 knees) with popliteus tendinitis via an auxiliary extreme lateral approach. Clinical outcomes were assessed using the Lysholm knee scoring scale, the Tegner score, the International Knee Documentation Committee (IKDC) score and the visual analogue scale (VAS) pain score at the 24-month follow-up after surgery.
UNASSIGNED: A total of 15 patients (mean age, 51.1 ± 7.1 years) were included. They had a mean body mass index of 23.8 ± 2.1 kg/m2. The minimum follow-up period was 24 months. Comparing the postoperative state to the preoperative state, the mean postoperative Lysholm score, Tegner score, and IKDC score improved significantly from 70.0 ± 5.0, 3.0 ± 0.9, and 62.3 ± 5.5 to 89.3 ± 4.2, 4.6 ± 0.61, and 80.5 ± 4.4, respectively (p < 0.01). The preoperative VAS score for pain improved from 6.4 ± 0.5 to 0.9 ± 0.4 (p < 0.01). No patients were lost to follow-up.
UNASSIGNED: Following arthroscopic-assisted treatment, all the patients with popliteus tendinitis achieved satisfactory clinical outcomes in terms of pain relief and improved function.
UNASSIGNED: Level IV.

The purpose of this study was to characterize the morphological variations in the distal attachment of the popliteofibular ligament (PFL) and create an accurate classification for use in planning surgical procedures in this area and in evaluating radiological imaging. One hundred and thirty-seven lower limbs of body donors fixed in 10% formalin solution were examined for the presence and course of the PFL. The PFL was present in 88.3% of cases. We propose the following three-fold classification: type I (72.3%), the most common type, characterized by the attachment onto the apex of the head of the fibula, type II (8.7%), characterized by a bifurcation, with the dominant band inserting on the anterior slope of the styloid process of the fibula and the smaller band onto the posterior surface of the styloid process of the fibula and type III (7.3%), characterized by a double PFL: the first PFL (main) originated from the popliteus tendon and inserted onto the anterior slope of the styloid process of the fibula, while the second originated from the musculotendinous junction of the popliteus muscle and inserted on the posterior surface of the styloid process of the fibula. The PFL was characterized by high morphological variation, as reflected in our proposed classification. This variation may present clinical and biomechanical issues for both medical personnel and researchers. Our proposed classification may be valuable for clinicians who evaluate and perform surgical procedures within the knee joint area.