Posterior Tibial Displacement Research Articles

Comparison of the Kinematics and Laxity of Total Knee Arthroplasty Bearing Designs Stabilized With Specimen-Specific Virtual Ligaments on a Joint Motion Simulator.

A variety of total knee arthroplasty (TKA) designs offer increased congruency bearing options, primarily to compensate for a loss of posterior cruciate ligament (PCL) function. However, their efficacy in providing sufficient stability under different circumstances requires further investigation. The preclinical testing of prosthesis components on joint motion simulators is useful for quantifying how design changes affect joint stability. However, this type of testing may not be clinically relevant because surrounding ligaments are either ignored or greatly simplified. This study aimed to assess the kinematics and stability of TKA joints during various motions using condylar-stabilized (CS) bearings without a PCL versus cruciate-retaining (CR) bearings with an intact PCL. TKA prosthetic components were tested on a joint motion simulator while being stabilized with five different sets of specimen-specific virtual ligament envelopes. In comparison to CR knees, CS knees without a PCL exhibited a greater amount of posterior tibial displacement laxity, with a mean increase of 2.7±2.1 mm (p = 0.03). Additionally, significant differences were observed in the anterior-posterior kinematics of the knee joint during activities of daily living (ADL) between the two designs. These results were consistent with previous cadaveric investigations, which indicated that CS knees without a PCL are less resistant to posterior tibial displacement than CR knees with one. This study employing virtual ligaments confirms previous findings that the raised anterior lip of some CS bearings may not completely compensate for the absence of the PCL; however, as both studies used reduced joint contact forces, the contributions of this design feature may be attenuated.

Intérêt des greffes au tendon peroneus longus deux brins et aux ischio jambiers quatre brins dans la reconstruction du ligament croisé postérieur

IntroductionPosterior cruciate ligament (PCL) injury hampers the rotational stability and stability front to back of the knee joint, seriously affecting the quality of life of patients. Some studies have reported that the peroneus longus tendon (PLT) has sufficient length and strength. HypothesisWe hypothesized that the PLT can be used as a novel appropriate material for PCL reconstruction therapy. Materials and methodsHerein, we systematically analysed the clinical effect of the double-stranded PLT and the four-stranded hamstring tendon in the reconstruction of the PCL and compared the effectiveness and safety of these two surgical approaches in the reconstruction of PCL injury. A total of 48 patients with complete rupture of the PCL were divided into Group A (reconstructed with the double-stranded PLT, 25 cases) and Group B (reconstructed with the four-stranded hamstring tendon, 23 cases). ResultsThe patients were followed up for more than 1 year. The intraoperative time for tendon extraction was significantly shorter in Group A than Group B. Twenty-four months after operation, patients in the two groups showed the alleviated tibial posterior displacement and the increased IKDC score, Lysholm score and Tegner score. Nevertheless, these scores showed no significant differences between the two groups. Additionally, compared with the therapy using the four-stranded hamstring tendon, therapy using the double-stranded PLT is simpler and safer. DiscussionBoth surgical methods are effective in the treatment of PCL injury. The PLT could be a good choice for PCL injury reconstruction material, especially when the four-stranded hamstring tendon is accidentally damaged or ineffective. Our study may provide guidance for the clinical treatment of PCL injury. Level of EvidenceIII, retrospective study.

The promotive effect of grafts with the double-stranded peroneus longus tendon and with the four-stranded hamstring tendon on reconstruction of the posterior cruciate ligament injury

IntroductionPosterior cruciate ligament (PCL) injury hampers the rotational stability and stability front to back of the knee joint, seriously affecting the quality of life of patients. Some studies have reported that the peroneus longus tendon (PLT) has sufficient length and strength. HypothesisWe hypothesized that the PLT can be used as a novel appropriate material for PCL reconstruction therapy. Materials and methods: Herein, we systematically analysed the clinical effect of the double-stranded PLT and the four-stranded hamstring tendon in the reconstruction of the PCL and compared the effectiveness and safety of these two surgical approaches in the reconstruction of PCL injury. A total of 48 patients with complete rupture of the PCL were divided into Group A (reconstructed with the double-stranded PLT, 25 cases) and Group B (reconstructed with the four-stranded hamstring tendon, 23 cases). ResultsThe patients were followed up for more than 1 year. The intraoperative time for tendon extraction was significantly shorter in Group A than Group B. Twenty-four months after operation, patients in the two groups showed the alleviated tibial posterior displacement and the increased IKDC score, Lysholm score and Tegner score. Nevertheless, these scores showed no significant differences between the two groups. Additionally, compared with the therapy using the four-stranded hamstring tendon, therapy using the double-stranded PLT is simpler and safer. DiscussionBoth surgical methods are effective in the treatment of PCL injury. The PLT could be a good choice for PCL injury reconstruction material, especially when the four-stranded hamstring tendon is accidentally damaged or ineffective. Our study may provide guidance for the clinical treatment of PCL injury. Level of EvidenceIII, retrospective study.

Experience in diagnosis and treatment of KD- ⅢM dislocation of knee joint

To explore the effectiveness of one-stage posterior medial corner (PMC) repair or reconstruction combined with anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) reconstruction in treating KD-ⅢM dislocation. The clinical data of 15 patients with knee KD-ⅢM dislocation who met the selection criteria between January 2016 and July 2019 were retrospectively analyzed. There were 9 males and 6 females, aged 22-61 years (mean, 40.3 years). Injuries were caused by violence of flexion, valgus, and external rotation, including 10 cases of traffic accident injuries, 3 cases of crush injuries, 1 case of winch injury, and 1 case of explosion injury. The time from injury to operation ranged from 3 days to 6 months, with an average of 18.5 days. PMC repair combined with PCL+ACL reconstruction was performed in 10 cases in acute stage (within 3 weeks after injury), including 3 cases of irreducible dislocation. PMC+PCL+ACL reconstruction was performed in 5 cases with chronic dislocation. Before operation and at last follow-up, the knee joint function was evaluated by Lysholm score and International Knee Documentation Committee (IKDC) 2000 score. KT-3000 was used to evaluate the forward stability of the knee (calculated the difference of tibial anterior displacement of both knees), the X-ray films of the stress position of the knee joint was used to evaluate the valgus of the knee (calculated the difference of medial joint space width of both knees) and the backward stability (calculated the difference of tibial posterior displacement of both knees), and the internal and external rotation stability was evaluated by knee flexion 30° tibial external rotation and knee flexion 90° tibial internal rotation tests (calculated the difference of tibial internal rotation and the difference of tibial external rotation of both knees). The operation time was 120-240 minutes, with an average of 186.5 minutes. Patients were followed up 24-48 months, with an average of 27.4 months. There was no complication such as infection, deep vein thrombosis, vascular injury, or heterotopic ossification. At last follow-up, the Lysholm score, IKDC2000 score, the difference of tibial anterior displacement of both knees, the difference of medial joint space width of both knees, the difference of tibial posterior displacement of both knees, the difference of tibial internal rotation and the difference of tibial external rotation of both knees significantly improved when compared with preoperative ones ( P<0.05). According to the IKDC2000 valgus stability grading standard, there were 3 cases of grade C and 12 cases of grade D before operation, and 10 cases of grade A and 5 cases of grade B at last follow-up, which was significantly improved when compared with that before operation ( Z=-4.930, P=0.000). At last follow-up, the pivot shift tests of 15 patients were negative. The anterior and posterior drawer tests of 10 patients were negative, 5 patients had mild instability, both the anterior and posterior drawer tests were positive. KD-ⅢM dislocation of the knee joint can lead to the posterior medial and anterior instability. Acute dislocation combined with "dimple sign" requires surgical reduction as soon as possible to repair PMC and reconstruct PCL and ACL. In chronic patients, PMC is difficult to repair, it is recommended to reconstruct PMC, PCL, and ACL at one stage to improve knee joint stability. The early and middle effectiveness are satisfactory.

Tibiofemoral Relationship 3 Weeks After Anatomic Triple-Bundle Anterior Cruciate Ligament Reconstruction With 10 N of Initial Tension Is Closer to Normal Knee Versus That With 20 N of Initial Tension

PurposeThis study aimed to clarify the effect of initial graft tension on the ensuing tibiofemoral relationship and on 2-year clinical outcomes after anatomic triple-bundle anterior cruciate ligament (ACL) reconstruction. MethodsA total of 31 patients with primary unilateral ACL rupture (mean age, 25.1 years) were enrolled. Anatomic triple-bundle ACL reconstruction was performed using semitendinosus tendon autografts, and patients were grouped according to the total initial tension at graft fixation: 20 N for 16 patients between January 2012 and December 2012 and 10 N for 15 patients between January 2013 and December 2013. Three-dimensional computed tomography scans were performed preoperatively and at 3 weeks and 6 months postoperatively. The side-to-side difference of the 3-dimensional tibial position relative to the femur was compared at each time point. The side-to-side difference in anterior laxity was sequentially compared preoperatively, immediately after surgery, and at 6 months and 2 years postoperatively. Clinical outcomes at 2 years were likewise compared. ResultsOne patient in each group was excluded because of secondary ACL injury. At 3 weeks postoperatively, 2.5 ± 1.3 and 1.0 ± 1.3 mm of posterior tibial displacement and 3.8° ± 2.4° and 2.0° ± 1.7° of external rotation were observed in the 20- and 10-N initial tension groups, respectively, with significant differences (P = .006 and .033). At 6 months postoperatively, anterior displacement was 0.1/0.1 mm and external rotation was 0.8°/0.4° in both groups, without any significant differences. The 2-year clinical outcomes were satisfactory, including mean side-to-side difference in anterior knee laxity of 0.5 mm in both groups. ConclusionThe tibiofemoral relationship 3 weeks after anatomic triple-bundle ACL reconstruction with 10 N of initial tension is less constrained than that with 20 N. Six-month tibiofemoral relationship and 2-year clinical outcomes are satisfactory in both groups. Level of EvidenceIII, retrospective comparative trial

Suture Tape–Augmented Posterior Cruciate Ligament Repair Should Be Tensioned and Fixed at Approximately 100° Knee Flexion to Prevent Loss of Full Flexion

PurposeTo evaluate the biomechanics of simulated posterior cruciate ligament injuries (SimPCL) with and without internal brace suture tape augmentation (IBSTA) in cadaver knees.MethodsA total of 20 cadaveric knees were used, all male, with an average age of 65 ± 18 years. Femoral tunnel isometry was evaluated at the 1/11 o’clock and 2/10 o’clock femoral positions. SimPCL were created in 6 knees. IBSTA was performed, and load data were collected through knee range of motion. An additional 6 specimens were evaluated at the 1/11 femoral tunnel position, and load cell recordings were obtained at 10 different knee flexion angles. Cyclic displacement in 8 cadaver knees was assessed using an Instron machine. Load and displacement data were recorded. Testing was performed under 3 conditions for each specimen: intact PCL, SimPCL, and SimPCL/IBSTA using the 1/11 femoral tunnel position.ResultsThere was no difference in isometry when comparing the 1/11 o’clock (7.1 ± 4.0 ft∗lb) femoral position and the 2/10 o’clock (7.6 ± 4.2 ft∗lb) position (P = .467). SimPCL/IBSTA suture tape tension gradually increased with progressive flexion to a peak at approximately 120° of knee flexion. For cycle 100 tibial displacement, there was no difference between intact (4.41 mm) and SimPCL/IBSTA (5.59 mm, P = .391). There was a difference between intact (4.41 mm) and SimPCL (7.19 mm, P = .006) , but there was no significant difference between SimPCL/IBSTA (5.59 mm) and SimPCL (7.19 mm, P = .140). There was a difference in cycle 1 stiffness between intact (62.3 N/mm) and Sim2PCL (37 N/mm, P = .005). There was no difference between other groups.ConclusionsIn this cadaver study, there was a 1.18-mm average difference in posterior tibial displacement when comparing intact and SimPCL/IBSTA. The internal brace construct should be tensioned and fixed at approximately 100° of knee flexion to prevent loss of full flexion.Clinical RelevanceThe presented biomechanical data for internal bracing of PCL injuries may lead to improved surgical techniques.

Clinically Reliable Knee Flexion Angle Measured on Stress Radiography for Quantifying Posterior Instability in Posterior Cruciate Ligament Injury.

Background:After posterior cruciate ligament injury, stress radiography is a common method of quantifying posterior instability, defined as the side-to-side difference in posterior tibial displacement (PTD) between the injured knee and contralateral noninjured knee. However, no study has evaluated the reliability of PTD according to knee flexion angle (KFA) measurements on stress radiographs.Purpose:To evaluate the test-retest reliability of stress radiographic measurements of the KFA in the noninjured knee. In addition, we established a reliable range of KFAs to indicate posterior instability by comparing results with the instability measured at 90° KFA, which is considered the gold standard.Study Design:Cohort study (diagnosis); Level of evidence, 3.Methods:We evaluated patients who had undergone bilateral stress radiographic examinations at least 5 times for ligament injuries between January 2013 and November 2019. All examinations were performed on a Telos device with a 150-N posterior load. A total of 120 knees and 644 stress radiographs were enrolled. We measured the KFA and PTD on stress radiographs and evaluated the reliability of repeated PTD measurement and the correlation between KFA and PTD.Results:The distribution of the actual noninjured knee KFA ranged from 56.9° to 106.7°. Among the 644 radiographs, 155 (24.1%) showed KFAs between 85° and 95°, and 287 (44.6%) showed KFAs between 80° and 85°. A significant correlation was found between KFA and PTD (P < .001), and the intrapatient intraclass correlation coefficient (ICC) was 0.788. A KFA range of 85° to 92° satisfied the criteria of high ICC (0.885) and nonsignificant correlation between KFA and PTD (P = .055) and thus was considered a reliable range of KFAs for quantifying posterior instability. We found no significant risk factors for measurement error, including age (P = .674), sex (P = .328), height (P = .957), weight (P = .248), or body mass index (P = .257).Conclusion:We found high reproducibility of posterior displacement measurements on Telos stress radiography at a KFA of 85° to 92° in noninjured knees.

Comparing the Efficacy of Kneeling Stress Radiographs and Weighted Gravity Stress Radiographs to Assess Posterior Cruciate Ligament Insufficiency

Background: Kneeling posterior cruciate ligament (PCL) stress radiographs are commonly used to evaluate PCL laxity. Patients, however, report significant pain, and the method’s reproducibility may be challenged due to its dependence on patient body weight distribution to produce posterior tibial displacement. Weighted gravity stress radiography may offer better reproducibility and comfort than the kneeling technique, but its efficacy has not been studied. Hypothesis: Weighted gravity PCL stress radiographs will be more comfortable and produce similar measurements of side-to-side difference in posterior tibial displacement when compared with the kneeling technique. Study Design: Cohort study (diagnosis); Level of evidence, 3. Methods: A total of 40 patients with nonoperatively or >6 months postoperatively treated PCL injuries (isolated or multiligamentous) underwent bilateral stress radiographs. Weighted gravity and kneeling stress radiographs were acquired, in random order, for each patient, as well as side-to-side difference in posterior tibial displacement between each knee, patient-reported visual analog scale knee pain (100 mm), time to acquire the images, and patient preference for technique. Paired t tests were used to compare the side-to-side difference, pain score, and time to complete the radiographs. Results: There was no difference between the 2 radiographic methods in the mean side-to-side difference (gravity: 6.45 ± 4.61 mm, kneeling: 6.82 ± 4.60 mm; P = .72), time required to acquire radiographs (kneeling: 307.3 ± 140.5 seconds, gravity: 318.7 ± 151.1 seconds; P = .073), or number of radiographs taken to obtain acceptable images (kneeling: 3.6 ± 1.6, gravity: 3.7 ± 1.7; P = .73). Patients reported significantly less knee pain during the weighted gravity views (kneeling: 31.8 ± 26.6, gravity: 4.0 ± 12.0; P < .0001). Of the patients, 88% preferred the weighted gravity method. Conclusion: Weighted gravity stress radiographs produce similar side-to-side differences in posterior tibial translation compared with the kneeling stress technique, but do not rely on patient weightbearing and provide significantly better patient comfort. Clinicians should therefore consider the use of weighted gravity stress radiographs in clinical practice to minimize the pain associated with stress radiography while allowing for accurate decision making.

Influence of the posterior cruciate ligament on kinematics of the knee during experimentally simulated clinical tests and activities of daily living

Clinical outcomes following posterior cruciate ligament (PCL) reconstruction are often suboptimal. A better understanding of the biomechanical contributions of the PCL to knee stability under physiologic, clinically-relevant loading conditions could improve reconstruction techniques and outcomes. We employed a servohydraulic joint motion simulator to investigate the kinematics of intact and PCL-deficient knees during simulated clinical tests and activities of daily living(ADL), including gait, stair ascent and descent. PCL transection caused the tibia to be displaced posterior, relative to the intact joint, throughout flexion. PCL transection also increased the amount of posterior tibial displacement measured during posterior laxity testing by up to 9.6 ± 1.7 mm at 75° (p = 0.001). During internal-external rotational laxity testing, PCL transection increased the allowable internal and external rotation of the tibia, by up to 2.9 ± 0.5°at90° (p = 0.001) and 1.0 ± 0.2° at45°(p = 0.001), respectively. PCL transection did not have a significant effect on abduction–adduction kinematics or laxity, regardless of flexion angle. PCL transection resulted in a relative posterior displacement of the tibia during the stance phase of gait when the knee was extended (2.2 ± 2.2 mm, p = 0.045), and when the knee was flexed during stair ascent (2.4 ± 2.2 mm, p = 0.035) and descent (1.6 ± 1.4 mm, p = 0.037). Our results support previous studies of the role of the PCL on neutral joint kinematics and laxity, and provide new data quantifying the effect of PCL transection on AP kinematics during simulated ADL.

Adoption of a new gait system to evaluate the clinical effects of minimally invasive needle-knife scope therapy for the treatment of rheumatoid arthritis of the knee joint.

The purpose of this study was to use kinematic gait analysis, to evaluate the clinically curative effects of minimally invasive needle-knife scope therapy in the treatment of rheumatoid arthritis (RA) of the knee joint. A total of 32 patients with RA of the knee joint were treated with minimally invasive needle-knife scope therapy. All patients were assessed with a kinematic gait analysis system, and then analyzed and compared the measurements with the kinematic gait performances of 28 healthy middle-aged and elderly participants. Before receiving the therapy, the ranges of motion (ROMs) of the patients' tibial inward and outward rotation, flexion and extension, anterior and posterior displacement of the tibia, and tibial upward and downward movement were all smaller than those of the healthy middle-aged and elderly group (P<0.05). After receiving the therapy, the patients' knees had a remarkably larger ROM. After one month of this therapy, they had a noticeably greater ROM in flexion and extension, tibial inward and outward rotation, and upward and downward movement of the tibia (P<0.05). After 1 month of therapy, the patients' maximum flexion angle and tibial posterior displacement angle were noticeably greater than beforehand (P<0.01). After 1 year of therapy, the patients' flexion and extension range became remarkably greater than it was after 1 month of the therapy (P<0.01). Their ranges of DOF reflected no apparent difference to the healthy middle-aged and elderly group, which remained smaller than the latter (P<0.05). After 1 year of therapy, the maximum values of the patients' flexion angle, tibial internal rotation angle, tibial posterior displacement angle, and tibial downward movement angle were remarkably higher than before commencing treatment (P<0.05). Minimally invasive needle-knife scope therapy enables a good recovery of function for patients with RA and remarkably improves the DOF of knees. Gait analyses are more objective, accurate, and quantitative than other indexes, and thus may become a new means to assess the changes in knee joint functions.

Arthroscopic reduction and internal fixation (ARIF) versus open reduction internal fixation (ORIF) to elucidate the difference for tibial side PCL avulsion fixation: a randomized controlled trial (RCT).

To compare the clinical, radiological outcomes, economic and technical differences for ORIF by cancellous screw fixation versus ARIF by double-tunnel suture fixation for displaced tibial-side PCL avulsion fractures. Forty patients with displaced tibial-sided PCL avulsions were operated upon after randomizing them into two groups (20 patients each in the open and arthroscopic group) and followed up prospectively. Assessment included duration of surgery, cost involved, pre- and post-operative functional scores, radiological assessment of union, and posterior laxity using stress radiography and complications. The mean follow-up period was 33months (27-42) (open group) and 30months (26-44) (arthroscopic group). The duration of surgery was significantly larger in the arthroscopic group (47.8 ± 17.9min) as compared to the open group (33.4 ± 10.1min). The costs involved were significantly higher in the arthroscopic group (p- 0.01). At final follow-up, knee function in the form of IKDC (International Knee Documentation Committee) evaluation (89.9 ± 4.8-open and 89.3 ± 5.9-arthroscopic) and Lysholm scores (94.2 ± 4.1-open and 94.6 ± 4.1-arthroscopic) had improved significantly with the difference (n.s.) between the two groups. The mean posterior tibial displacement was 5.7 ± 1.8mm in the open group and 6.3 ± 3.1mm in the arthroscopic group which was (n.s.). There were two non-unions and one popliteal artery injury in the arthroscopic group. Both ARIF and ORIF for PCL avulsion fractures yield good clinical and radiological outcomes. However, ORIF was better thanARIF in terms of cost, duration of surgery, and complications like non-union and iatrogenic vascular injury. II.

Early effectiveness of minimally invasive open reduction and internal fixation versus arthroscopic double-tunnel suture fixation for tibial avulsion fracture of posterior cruciate ligament

To compare the early effectiveness of minimally invasive open reduction and internal fixation via posterior median approach versus arthroscopic double-tunnel suture fixation in treatment of tibial avulsion fracture of the posterior cruciate ligament (PCL). A clinical data of 31 patients with the tibial avulsion fracture of the PCL and met the criteria between January 2015 and January 2019 was retrospectively analyzed. Nineteen patients (group A) were treated with open reduction and internal fixation with cannulated screw via posterior median approach. The other 12 patients (group B) were treated with arthroscopic double-tunnel suture fixation technique. There was no significant difference between the two groups ( P>0.05) in the gender, age, side of effected limb, the injury cause, the time from injury to operation, the combined meniscus injury, Meyers & McKeever classification and preoperative Lysholm score, Tegner score, International Knee Documentation Committee (IKDC) score, and the difference of tibial posterior displacement between bilateral knees. The operation time, postoperative complications, fracture healing, and the difference of tibial posterior displacement between bilateral knees, Lysholm score, Tegner score, and IKDC score were recorded. Group B spent significantly longer operation time than group A ( t=7.347, P=0.000). No postoperative complication occurred in group B, and 1 patient in group A had a screw breakage. All patients were followed up 6-36 months (mean, 22 months). X-ray films showed that all fractures healed at 3 months after operation. At last follow-up, there was no significant difference in the patients with normal knee range of motion between the two groups ( P=0.510). At last follow-up, the difference of tibial posterior displacement between bilateral knees, Lysholm score, Tegner score, and IKDC score in the two groups were superior to those before operation ( P<0.05); while there was no significant difference between the two groups ( P>0.05). For the tibial avulsion fracture of PCL, the minimally invasive open reduction and internal fixation and arthroscopic double-tunnel suture fixation can obtain similar early effectiveness. However, arthroscopic surgery has the advantages of being able to simultaneously deal with intra-articular combined injuries, avoiding internal fixator complications, and eliminating the need for secondary operation.

Comparing the Efficacy of Kneeling Stress Radiographs and Weighted Gravity Stress Radiographs to Assess Posterior Cruciate Ligament Insufficiency

Objectives: Kneeling stress radiographs are commonly used to evaluate posterior cruciate ligament (PCL) laxity. Patients, however, report significant pain, and reproducibility is challenged due to its dependence on patient body weight distribution to produce posterior tibial displacement (PTD). Weighted gravity stress radiographs may offer better reproducibility and comfort than the kneeling technique, but its efficacy has not been studied. Hypothesis: weighted gravity radiographs will be more comfortable and produce similar PTD measurements when compared to the kneeling technique. Methods: Patients 18-70 years old with non-operatively or &gt;6 months post-operatively treated PCL injuries (isolated or multi-ligamentous) were recruited from two academic level one trauma centers to undergo bilateral PCL stress radiographs. Exclusions: open/bilateral injuries, fractures. Patients underwent PCL stress radiographs by two randomly ordered methods. Kneeling stress views: patients knelt on padded scales (separate for each knee) with the padding distal to the tibial tubercle. Patients were verbally encouraged to place equal weight on both knees (scale outputs not visible to the patient). A digital radiography plate was placed between the legs to acquire bilateral lateral radiographs. Weighted gravity stress views: Patients lay supine with their hip and knee at 90°with the heel supported. A 20 lb weight was placed on the anterior tibia just distal to the tibial tubercle. A lateral radiograph was taken and then repeated on the contralateral leg. Images were anonymized and uploaded to PACS for measurement. Outcomes: side to side difference (SSD) in translation of the posterior tibial condyles relative to the posterior femoral condyles (primary outcome); patient-reported VAS knee pain (100 mm) during the radiographs; time required to acquire the images; patient preference for technique. Statistics: sample size = 31 patients to detect a 2 mm difference (α=0.05, power 80%, SD = 2.8 mm [Jung, 2006]). Paired t-tests were used to compare the SSD between the kneeling and weighted gravity methods, VAS pain, and time to complete the radiographs. Results: 40 patients (77.5% male, 34.5 ± 12.8yrs old, 65% left knee) were recruited. 42.5% had undergone PCL reconstruction. There was no difference between the two radiographic methods in the mean SSD (kneeling = 6.29 ± 4.58 mm, gravity = 6.82 ± 4.60 mm, p= 0.61). There was no difference in the total time required to perform the radiographs (kneeling = 307.3 s ± 140.5 s, gravity = 318.7 s ± 151.1 s, p= 0.73) or the number of radiographs taken to obtain acceptable images (kneeling = 3.6 ± 1.6, gravity = 3.7 ± 1.7, p= 0.73). The amount of weight placed on each knee during the kneeling views differed slightly but was not significant (affected = 21.5 ± 11.3 kg, unaffected = 26.1 ± 12.1 kg, p= 0.09). There was significantly less knee pain reported for the gravity views (kneeling = 31.8 ± 26.6, gravity = 4.0 ± 12.0, p &lt; 0.0001). 94.6% of patients preferred the gravity method. Conclusion: Weighted gravity PCL stress radiographs should be considered for use in clinical practice as they produce similar posterior tibial translation values to the kneeling technique, do not rely on patient weightbearing, and provide significantly better patient comfort.

THE EFFECTS OF POSTERIOR TIBIAL MOBILIZATION ON MENISCAL MOVEMENT: AN IN-SITU INVESTIGATION

Anterior knee pain during knee extension may be related to a meniscal movement restriction and increased meniscal load during function. One method of treatment involves the use of manual posterior mobilization of the tibia to specifically target the meniscotibial interface of the knee joint. The purpose of this study was to measure motion at a cadaveric medial meniscus anterior horn during a posterior tibial mobilization. Prospective, multifactorial, repeated-measures laboratory study. Eight unembalmed cadaveric knee specimens were mounted in a custom apparatus and markers were placed in the medial meniscus, tibia and femur. The tibia was posteriorly mobilized in two randomized knee positions (0 degrees and 25 degrees) using three randomly assigned loads (44.48N, 88.96N, and 177.93N). Markers were photographed and digitally measured and analyzed. All load x position conditions produced anterior displacement of the meniscus on the tibia, where the displacement was significant [t (7) = -3.299; p = 0.013] at 0 degrees loaded with 177.93N (mean 0.41 ± 0.35 mm). The results of 2(position) x 3(load) repeated measures ANOVA for meniscotibial displacement produced no significant main effects for load [F (2,14) = 2.542; p = 0.114) or position [F (1,7) = 0.324, p = 0.587]. All load x position conditions produced significant posterior tibial and meniscal displacement on the femur. The 2(position) x 3(load) repeated measures ANOVA revealed a significant main effect for load for both femoral marker displacement relative to the tibial axis [F (2,14) = 77.994; p < 0.001] and meniscal marker displacement relative to the femoral marker [F (2,14) = 83.620; p < 0.001]. Use of a mobilization technique to target the meniscotibial interface appears to move the meniscus anteriorly on the tibia. It appears that this technique may be most effective at the end range position. 2 (laboratory study).

The role of menisci in knee contact mechanics and secondary kinematics during human walking

BackgroundMeniscectomy is likely to result in an increase of joint loading on articular cartilage and initiates cartilage damages. However, the induced alterations in knee contact mechanics and secondary kinematics after the meniscal removal are still unclear during a walking gait. In this study, the role of menisci on the knee contact mechanics and secondary kinematics were investigated during a walking simulation. MethodsTwo natural knee models with or without menisci were established using a musculoskeletal multibody dynamics framework. Walking simulation were performed to qualify the knee contact forces and secondary kinematics, and ligament forces in these models. FindingsAfter the meniscal removal, the redistributed contact forces on the medial tibial cartilage increased by twofold, while the contact area remained almost the same. The subsequent increase of contact pressure suggested potential cartilage damages. In terms of the kinematic alterations, the tibia moved more posteriorly and internally with respect to the femur. And, the displacement in the medial-lateral direction reversed. In addition, the sharp force increase in the anterior cruciate ligament explained the reason why meniscal and anterior cruciate ligament injuries always happened concurrently. And, the anterior lateral ligament may act as the stabilizer in the tibial posterior displacement and varus rotation. InterpretationThis study shows that menisci served as the joint load distribution, and also as the kinematics constraints in the posterior and medial-lateral direction, which is beneficial to the rehabilitation plan-making of meniscal injuries.

Mechanisms of anterior-posterior stability of the knee joint under load-bearing

The anterior-posterior (AP) stability of the knee is an important aspect of functional performance. Studies have shown that the stability increases when compressive loads are applied, as indicated by reduced laxity, but the mechanism has not been fully explained. A test rig was designed which applied combinations of AP shear and compressive forces, and measured the AP displacements relative to the neutral position. Five knees were evaluated at compressive loads of 0, 250, 500, and 750N, with the knee at 15° flexion. At each load, three cycles of shear force at ±100N were applied. For the intact knee under load, the posterior tibial displacement was close to zero, due to the upward slope of the anterior medial tibial surface. The soft tissues were then resected in sequence to determine their role in AP laxity. After anterior cruciate ligament (ACL) resection, the anterior tibial displacement increased significantly even under load, highlighting its importance in stability. Meniscal resection further increased displacement but also the vertical displacement increased, implying the meniscus was providing a buffering effect. The PCL had no effect on any of the displacements under load. Plowing cartilage deformation and surface friction were negligible. This work highlighted the particular importance of the upward slope of the anterior medial tibial surface and the ACL to AP knee stability under load. The results are relevant to the design of total knees which reproduce anatomic knee stability behavior.

Does a third condyle TKA restore normal gait kinematics in varus knees? In vivo knee kinematic analysis.

Patients with knee osteoarthritis tend to modify spatial and temporal parameters during walking to reduce the pain. Total knee arthroplasty (TKA) is considered the gold standard treatment for end-stage knee osteoarthritis. However, reduced physical function of the knee is partly, but apparently not fully, remedied by surgery. The purpose of this study was to investigate the in vivo, three dimensional knee kinematics during gait at the patients with knee osteoarthritis and the influence of "third condyle" psoterior stabilized (PS) total knee arthroplasty on restoration of normal kinematics. Twenty patients with medial knee osteoarthritis and a control group with age-matched subjects were prospectively collected for this study. The same group of 20 patients were re-assessed 10months after total knee arthroplasty with "third condyle" PS prosthesis. All subjects were assessed with a 3D, optoelectric knee assessement device, while walking on a treadmill at a self-selected speed. For each participant, knee flexion-extension, abduction-adduction, internal-external rotation and anterior-posterior displacement, were calculated. The range of flexion/extension was improved significantly (39.9°±5.5° vs 44.8°±5.1°, p < 0.05) after TKA but it still remained lower than control group (6.9°±5.5° vs 2.2°±3.9°, p < 0.05). The range of motion in internal-external rotation did not change pre- and post-arthroplasty, but remained lower than the matched control group (6.7°±2.4° vs 9.3°±2.4, p < 0.05). The maximum posterior displacement during swing phase was significantly higher at post-arthroplasty group comparing with control group (-9.5 ± 2.2 vs -5.7 ± 3mm, p < 0.05). Following "third condyle" PS-TKA, patients had better clinical, spatiotemporal and kinematic parameters. Despite improvements, the knee kinematics during gait in TKA group differed from healthy control group. TKA group had a lower extension lower range of axial rotation and an increased tibial posterior displacement.

Posterior tibial tendon displacement behind the tibia and its interposition in an irreducible isolated ankle dislocation: a case report and literature review.

Isolated posteromedial ankle dislocation is a rare condition thanks to the highly congruent anatomical configuration of the ankle mortise, in which the medial and lateral malleoli greatly reduce the rotational movement of the talus, and the strength of the ligaments higher than the malleoli affords protection against fractures. However, other factors, like medial malleolus hypoplasia, laxity of the ligaments, peroneal muscle weakness and previous ankle sprains, could predispose to pure dislocation. In the absence of such factors, only a complex high-energy trauma, with a rotational component, can lead to this event. Irreducibility of an ankle dislocation, which is rarely encountered, can be due to soft tissue interposition. Dislocation of the posterior tibial tendon can be the cause of an irreducible talar dislocation; interposition of this tendon, found to have slid posteriorly to the distal tibia and then passed through the tibioperoneal syndesmosis, is reported in just a few cases of ankle fracture-dislocation.

Posterior tibial displacement in the PCL-deficient knee is reduced compared to the normal knee during gait.

Most individuals with an isolated posterior cruciate ligament (PCL) injury do not complain of disability even if posterior instability is objectively revealed by a static physical examination, such as the posterior drawer test. This suggests it is insufficient to only evaluate posterior instability under static conditions. Therefore, we have investigated the effect of isolated PCL injury on the detailed kinematics of the knee in a dynamic environment such as during gait. Eight unilateral PCL-deficient males and eight healthy control volunteers participated in this study. Isolated PCL injury was diagnosed by clinical examination. Stress X-ray imaging showed an average side-to-side difference of 12.7 ± 3.5 mm. Knee kinematics including anteroposterior tibial displacement were analysed during walking using the point cluster technique. Posterior tibial displacement from initial contact was significantly smaller during 9-22 % of the gait cycle by an average of 0.4 cm in the PCL group, compared to controls. In the PCL-deficient knee, the external rotational angle increased by an average of 3.3° at the loading response during 3-11 % of the gait cycle and the varus angle from initial contact increased by an average of 2.0° during 28-52 % of the gait cycle, compared to controls. Dynamic changes in the rotation and posterior translation patterns were seen after isolated PCL injury, suggesting the kinematics of PCL-deficient knees might be different to normal knees. These factors may contribute to long-term osteoarthritic change. Consequently, when choosing conservative treatment for PCL injury, these changes should be considered to prevent osteoarthritic change. III.

Effect of posterior cruciate ligament creep on muscular co-activation around knee: A pilot study

The effect of posterior cruciate ligament (PCL) on muscle co-activation (MCO) is not known though MCO has been extensively studied. The purpose of the study was to investigate the effect of PCL creep on MCO and on joint moment around the knee. Twelve males and twelve females volunteered for this study. PCL creep was estimated via tibial posterior displacement which was elicited by a 20kg dumbbell hanged on horizontal shank near patella for 10min. Electromyography activity from both rectus femoris and biceps femoris as well as muscle strength on the right thigh was recorded synchronically during knee isokinetic flexion–extension performance in speed of 60deg/s as well as 120deg/s on a dynamometer before and after PCL creep. A one-way ANOVA with repeated measures was used to evaluate the effect of creep, gender and speed. The results showed that significant tibial posterior displacement was found (p=0.01) in both male and female groups. No significant increase of joint moment was found in flexion as well as in extension phase in both female and male groups. There was a significant effect of speed (p=0.036) on joint moment in extension phase. Co-activation index (CI) decreased significantly (p=0.049) in extension phase with a significant effect of gender (p⩽0.001). It was concluded that creep developed in PCL due to static posterior load on the proximal tibia could significantly elicit the increase of the activation of agonist muscles but with no compensation from the antagonist in flexion as well as in extension phase. The creep significantly elicited the decrease of the antagonist–agonist CI in extension phase. MCO in females was reduced significantly in extension phase. It was suggested that PCL creep might be one of risk factors to the knee injury in sports activity.