Expanding the clinical phenotype of RASopathies in 38 Turkish patients, including the rare LZTR1, RAF1, RIT1 variants, and large deletion in NF1.

RASopathies are a group of disorders caused by pathogenic variants in the genes encoding Ras/mitogen-activated protein kinase pathway and share overlapping clinical and molecular features. This study is aimed to describe the clinical and molecular features of 38 patients with RASopathies. Sanger or targeted next-generation sequencing of related genes and multiplex ligation-dependent-probe amplification analysis for NF1 were performed. The pathogenic variant detection rate was 94.4%. While PTPN11 was responsible for 50% of 18 patients with Noonan syndrome (NS), SOS1, LZTR1, RIT1, and RAF1 were responsible for the remaining 27.8%, 11.1%, 5.5%, and 5.5%, respectively. Three variants in LZTR1 were novel, of which two were identified in the compound heterozygous state in a patient with intellectual disability and hypertrophic cardiomyopathy, whereas the third variant was found in the heterozygous state in a patient with pulmonary stenosis and normal intelligence. We described pyloric stenosis, knee dislocation, and cleft palate in patients with SOS1, RIT1, and RAF1 variants, respectively, that was not previously reported. We detected a PTPN11 variant in three patients from same family with NS with multiple lentigines. BRAF and MAP2K2 variants were found in eight patients with Cardiofaciocutaneous syndrome. Two variants in HRAS were detected in two Costello syndrome patients, one with a mild and the other with a severe phenotype. While large NF1 deletions were identified in four Neurofibromatosis-NS patients with intellectual disability, intelligence was normal in one patient with missense variant. In conclusion, this study provided three novel variants in LZTR1 and expanded the clinical phenotype of rare RASopathies.

Is There a Disadvantage to Early Physical Therapy After Multiligament Surgery for Knee Dislocation? A Pilot Randomized Clinical Trial.

BACKGROUND: Multiligament knee injuries, though rare, can be profoundly disabling. Surgeons disagree about when to initiate rehabilitation after surgical reconstruction due to the conflicting priorities of postoperative stability and motion. QUESTIONS/PURPOSES: (1) Does early or late initiation of physical therapy after multiligament knee surgery result in fewer postoperative manipulations? (2) Does early versus late physical therapy compromise stability postoperatively? (3) Does early initiation of physical therapy result in improved patient-reported outcomes, as measured by the Multi-ligament Quality of Life (ML-QOL) score? METHODS: Between 2011 and 2016, 36 adults undergoing multiligament repair or reconstruction were prospectively enrolled in a randomized controlled trial and randomized 1:1 to either early rehabilitation or late rehabilitation after surgery. Eligibility included those with an injury to the posterior cruciate ligament (PCL) and at least one other ligament, as well as the ability to participate in early rehabilitation. Patients who were obtunded or unable to adhere to the protocols for other reasons were excluded. Early rehabilitation consisted of initiating a standardized physical therapy protocol on postoperative day 1 involving removal of the extension splint for quadriceps activation and ROM exercises. Late rehabilitation consisted of full-time immobilization in an extension splint for 3 weeks. Following this 3-week period, both groups engaged in the same standardized physical therapy protocol. All surgical reconstructions were performed at a single center by one of two fellowship-trained sports orthopaedic surgeons, and all involved allograft Achilles tendon PCL reconstruction. When possible, hamstring autograft was used for ACL and medial collateral ligament reconstructions, whereas lateral collateral ligament and posterolateral reconstruction was performed primarily with allograft. The primary outcome was the number of patients undergoing manipulation during the first 6 months. Additional outcomes added after trial registration were patient-reported quality of life scores (ML-QOL) at 1 year and an objective assessment of laxity through a physical examination and stress radiographs at 1 year. One patient from each group was not assessed for laxity or ROM at 1 year, and one patient from each group did not complete the ML-QOL questionnaires. No patient crossover was observed. RESULTS: With the numbers available, there was no difference in the use of knee manipulation during the first 6 months between the rehabilitation groups: 1 of 18 patients in the early group and 4 of 18 patients in the late group (p = 0.34). Similarly, there were no differences in knee ROM, stability, or patient-reported quality of life (ML-QOL) between the groups at 1 year. CONCLUSION: With the numbers available in this study, we were unable to demonstrate a difference between early and late knee rehabilitation with regard to knee stiffness, laxity, or patient-reported quality of life outcomes. The results of this small, randomized pilot study suggest a potential role for early rehabilitation after multiligament reconstruction for knee dislocation, which should be further explored in larger multi-institutional studies. LEVEL OF EVIDENCE: Level II, therapeutic study.

Dislocation of modern design rotating hinge total knee arthroplasty : case series and narrative review.

Knee dislocation is an infrequent complication after rotating hinge total knee arthroplasty (RHTKA). The aim of the present study was to describe our experience with dislocating RHTKA in a consecutive prospective large series, its occurrence rate, causative mechanisms and to perform a review of available literature. In total, six dislocations were observed in 303 RHTKA procedures (NexGen RHK, ZimmerBiomet, Warsaw, Indiana, US) at a mean of 10 (range, 2 - 24) months after surgery. This results in a 2% dislocation rate, which is lower than the 3.1% cumulative rate reported earlier in literature. Men and women were distributed equally, with a mean age of 56 years old. The indication for RHTKA among the six dislocations was revision in 4 cases and primary arthroplasty for the other 2 cases. Analysis revealed that the main mechanism of hinge dislocation was forced knee flexion with concomitant extensor mechanism insufficiency (4/6 cases). The second cause was unscrewing of the locking pin (2/6 cases). This is probably caused by the screw home mechanism that results in a counterclockwise torque -and therefore a loosening- effect on locking bolts, specifically in right-sided RHTKA. Obesity probably predisposes to hinge dislocation since 83% of patients in this series were obese (BMI, range 34 to 52). The findings of this study suggest that dislocation of RHTKA is a rare complication that could happen to obsese patients without an adequate extensor mechanism. Level of evidence : IV.

Knee Ligament Instability Patterns: What Is Clinically Important.

The knee dislocation is a severe, complex injury that can be difficult to treat and is fraught with complications. The first step in a successful reconstruction of a multiple ligamentous knee injury is gaining an accurate and thorough understanding of the pattern of instability imparted by the injury. Evaluation begins with a detailed review of radiographic and advanced imaging studies followed by a thorough physical examination, often done under anesthesia, in conjunction with dynamic fluoroscopy. Failure to identify and reconstruct a damaged ligament may place undue stress on adjacent structures, resulting in complications and potential failure of the surgical procedure.

The Biomechanics of Multiligament Knee Injuries: From Trauma to Treatment.

The multiple ligament injured knee is a complex biomechanical environment. When primary stabilizers fail, secondary stabilizers have an increased role. In addition, loss of primary restraints puts undue stress on the remaining intact structures of the knee. Treatment of these injuries requires accurate diagnosis of all injured structures, and careful consideration of repairs and reconstructions that restore the synergistic stability of all ligaments in the knee.

Association of Injury Energy Level and Neurovascular Injury Following Knee Dislocation.

OBJECTIVE: To describe the associations between mechanism of injury energy level and neurovascular injury (NVI) following knee dislocation (KD) using a large representative sample of trauma patients and to examine risk factors within these groups. DESIGN: Retrospective cohort study. SETTING: Trauma centers participating in the American College of Surgeons National Trauma Data Bank. PARTICIPANTS: Adult patients with KD without lower extremity fracture. INTERVENTION: Patients were grouped as ultra-low, low, or high-energy based on injury mechanism. Univariate/multivariate analyses assessed associations of energy level with NVI and of patient characteristics with NVI within energy-level groups. MAIN OUTCOME MEASUREMENTS: Rate of nerve and blood vessel injury. RESULTS: One hundred twenty-four patients with KD were identified; 181 sustained ultra-low-energy mechanisms, 275 low-energy, and 868 high-energy. Nerve injury occurred in 6% of ultra-low-energy injuries, 7% in low-energy, and 3% in high-energy (P = 0.03). Vessel injury occurred in 21% of ultra-low-energy injuries, 17% in low-energy, and 13% in high-energy (P = 0.01). On multivariate analyses, obesity was associated with nerve injury in the ultra-low-energy group (OR 4.9; 95% CI 1.0-24.0) but not with other energy levels. Obesity was also associated with vessel injury in the ultra-low-energy group (OR 4.0; 95% CI 1.6-9.7). Smoking, hypertension, and diabetes were not associated with NVI. CONCLUSIONS: NVI following KD is more common after lower energy-level mechanisms. Obesity is associated with NVI in lower energy-level mechanisms. Physicians should be vigilant in screening for NVI in the setting of KD even with seemingly benign mechanisms of injury, especially in patients with obesity. LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Epidemiology and outcomes of traumatic knee dislocations: Isolated vs multi-trauma injuries.

BACKGROUND AND PURPOSE: Traumatic dislocation of the knee (TKD) is a rare injury, accounting for approximately 0.02% of orthopaedic injuries. They are a challenging entity for orthopaedic surgeons to manage, and can have devastating consequences. The aim of this study was to describe the epidemiology of traumatic knee dislocations (TKD'S) and contrast the incidence of neurovascular injury between isolated and multi-trauma dislocations as well as key patient reported outcomes achieved between these groups. MATERIAL AND METHODS: Patients who had a traumatic disruption of the tibiofemoral articulation between March 1 2007 and February 31, 2015 were identified from the Victorian Orthopaedic Trauma Outcomes Registry (VOTOR). Data was cross-checked with medical records and radiological reports to confirm true multi-ligamentous dislocation. VOTOR collects information pertaining to orthopaedic injuries, treatment, complications and outcomes from four adult hospitals in Victoria, Australia, including the major trauma centers. Patient-reported outcomes are collected by VOTOR at 12 months post-injury including the EQ-5D-3L (EQ-5D) and Glasgow Extended Outcome Scores (GOS-E) and return to work status. Patient reported functional and quality of life outcomes at 12 months after injury were analysed. RESULTS: A cohort of 88 patients were identified that fit the inclusion criteria for the study, and at 12 months post-injury there was data available for 80 patients (90.9%). There were 38 (42.9%) patients who experienced an isolated traumatic knee dislocation and 52 (57.1%) who experienced a traumatic knee dislocation in association with another injury. Of the 88 patients identified as eligible for the study, two had bilateral knee dislocations, hence there were 90 multi-ligamentous knee injuries. Those who were injured at a higher velocity were more likely to have additional injuries. Dislocations that occurred at a lower velocity were shown to have better overall outcomes, as did dislocations that occurred in isolation. CONCLUSIONS: Traumatic knee dislocations that occur in isolation typically result in better outcomes than those that occur with associated injuries. TKD's are a rare but severe injury that requires further research in order for functional outcomes to be optimized.

Poly-traumatic multi-ligament knee injuries: is the knee the limiting factor?

PURPOSE: Multi-ligament knee injuries (MLKI) from a high-velocity accident are rare but potentially devastating. This matched cohort analysis compares knee functional outcomes after multiple ligament reconstruction in poly-trauma patients to those that occurred in isolation. METHODS: Sixty-two patients with MLKI that occurred either as a component of polytrauma or had occurred in isolation were matched according to age, sex, and knee dislocation grade. Functional outcomes and knee physical examination were assessed at a 2-year follow-up. New Injury Severity Score (NISS) was calculated based on the poly-traumatic injury pattern. Risk factors for worse outcomes in the poly-trauma cohort were analyzed. RESULTS: The mean IKDC, Lysholm, and NISS scores in the polytrauma cohort were 57.2 ± 21.9, 62 ± 22, and 40.9 ± 20.4, respectively, at a mean of 67 months (range 24-220). The isolated knee injury group was followed for a mean of 74 months (range 24-266) with mean IKDC and Lysholm scores of 71.1 ± 26.5 and 78 ± 23, respectively. Patients in the control cohort had significantly higher IKDC (p = 0.01) and Lysholm scores, (p = 0.003). There were no major differences between the two groups in regards physical examination findings at final follow-up. None of the analyzed risk factors was predictive of poor outcome. CONCLUSION: When comparing knees with similar multi-ligament and neurovascular injury patterns, patients who sustained their injury as a result of poly-trauma demonstrated significantly lower functional scores following reconstruction. This is despite restoration of similar knee stability and range of motion. The functional outcomes following MLKI reconstruction in poly-traumatized patients are influenced by factors other than the knee including concomitant injuries and psychosocial factors. LEVEL OF EVIDENCE: Therapeutic Level III.

Effect of Vascular Injury on Functional Outcome in Knees with Multi-Ligament Injury: A Matched-Cohort Analysis.

BACKGROUND: Multi-ligament knee injury (MLKI) associated with knee dislocation can result in vascular injury. The purpose of this study was to compare knee function after MLKI between patients with a vascular injury requiring popliteal artery bypass grafting and patients without vascular involvement. Additionally, factors associated with poor knee function in patients who had MLKI with vascular injury were evaluated. METHODS: This retrospective study identified patients with an MLKI between 1992 and 2014. Each patient who had a concomitant vascular injury requiring bypass grafting (vascular cohort, n = 16; mean age, 30.3 years) was matched to 2 patients without a vascular injury (control cohort, n = 32; mean age, 31.4 years) on the basis of age, knee dislocation (KD) grade, and peroneal nerve status. Fifteen patients in the vascular cohort and 26 patients in the control cohort had an isolated knee injury. Functional outcomes were assessed with physical examination of range of motion and ligamentous stability as well as patient-reported outcome scores. RESULTS: The vascular cohort had a mean Lysholm score of 62.5 points (range, 16 to 100 points) and a mean International Knee Documentation Committee (IKDC) score of 59.7 points (range, 14.9 to 100 points) at a mean (and standard deviation) of 8.3 ± 5.0 years after surgery. The control cohort had a mean Lysholm score of 86.4 points (range, 51.0 to 100.0 points) and a mean IKDC score of 83.8 points (range, 35.6 to 100.0 points) at a mean of 6.0 ± 4.0 years. The vascular cohort had significantly lower Lysholm (p = 0.001) and IKDC (p = 0.002) scores than the control cohort. A body mass index (BMI) of >30 kg/m was predictive of lower IKDC (p = 0.0009) and Lysholm (p = 0.0008) scores. CONCLUSIONS: Patients who sustain an MLKI with an associated popliteal artery injury requiring bypass grafting have significantly lower knee function scores than patients without vascular involvement. This information can be used to help counsel patients with combined multiple ligament and popliteal artery injuries. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Clinical and Functional Results of 119 Patients With Knee Dislocations.

OBJECTIVES: To describe clinical results and functional outcomes of knee dislocations treated with a consistent strategy within our institution. DESIGN: Retrospective case series. SETTING: Level 1 trauma center. PATIENTS: One hundred nineteen patients were treated at one institution between 2000 and 2014 for knee dislocation. MAIN OUTCOME MEASUREMENTS: Knee range of motion, functional instability, and complications were recorded. Musculoskeletal Function Assessment (MFA) and Lysholm scores were obtained after minimum of 1 year. RESULTS: Sixty-three early complications were noted in 36 patients (32%), with an overall amputation rate of 9.2% (8 early and 3 late amputations). Of the patients who retained their limb, 4.5% reported instability. Open knee dislocations were associated with amputation (26% vs. 1.3%, P < 0.001). Popliteal arterial injuries were associated with more amputation (31% vs. 3.2%, P = 0 < 0.001), infection (37% vs. 8%, P = 0.002), and deep venous thrombosis (32% vs. 8.8%, P = 0.014). Patients with wound infection were more likely to develop heterotopic ossification (36% vs. 9.4%, P = 0.017) and less knee motion (77.5 vs. 117 degrees P = 0.049). Knee motion improved over time for all patients with a mean arc of 86 degrees at 3 months, 109 degrees at 6 months, and 115 degrees at 12 months. An Injury Severity Score of ≥20 was associated with less knee motion (97 vs. 121 degrees P = 0.029). Mean Lysholm score was 86.7, and mean MFA score was 35.7 after mean follow-up of 90 months and 82 months, respectively. CONCLUSIONS: Few patients (4.5%) experienced functional instability. However, early complications occurred frequently (32%) as expected, particularly in patients with open injuries and/or arterial injury. Limitations in knee motion were associated with high Injury Severity Score, infection, and heterotopic ossification. Mean knee scores were good, consistent with reasonable knee function, although MFA scores suggest a lower level of generalized function. LEVEL OF EVIDENCE: Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Traumatic Anterior Knee Dislocation with Popliteal Artery Injury: The Importance of a Prompt Diagnosis and Treatment to Obtain Lower Limb Salvage.

We report a case of traumatic anterior dislocation of the left knee in association with disruption of the soft tissues including knee ligaments, popliteal artery, and common peroneal nerve, resulting in lower limb acute ischemia. All components of this complex trauma were recognized and treated promptly. First, he was submitted to closed reduction of the dislocated knee under general anesthesia; right after he underwent superficial femoro-tibioperoneal trunk bypass using a reversed saphenous contralateral vein recurring to a posterior approach through a popliteal S-shaped incision; rehabilitation program was initiated early; a second and final reconstructive orthopedic operation was carried out in a different center. The present case is important in 2 aspects. First, it reports a very rare occurrence of simultaneous anterior dislocation of the knee associated with vascular insult and common peroneal nerve injury, which was rarely reported in the current literature; second, it highlights that with timely intervention and a team approach, excellent results could be achieved.

Total joint replacement for neglected posterior knee dislocation following septic arthritis after arthroscopy.

This report presents the first case of a knee dislocation following septic arthritis after arthroscopy. A 65-year-old woman had an arthroscopy with irrigation and debridement (I&D) of the joint and microfracture for the chondral lesions. She had complaints of postarthroscopic infection but non-steroidal anti-inflammatory medication and local ice compression was recommended. She revisited her physician twice and at the last visit she had a large purulent effusion in her knee. The gram stain of the joint fluid aspirate demonstrated gram-positive cocci and the cultures grew methicilline-sensitive Staphylococcus aureus. She underwent arthroscopic assisted I&D and received intravenous antibiotics. I&D was repeated after two weeks. Intravenous antibiotherapy was continued for one more week and was changed to oral antibiotherapy for six weeks. At the third month visit's physical examination, a deformity at the knee was noticed and was referred to us for further treatment. A posterior knee dislocation with no neurovascular deficit was detected. The patient had a history of knee sprain but did not seek medical advice immediately. The blood samples showed no abnormality. The patient underwent a surgery with a cemented hinged revision total knee prosthesis following the exclusion of the active knee joint infection. Intraoperative frozen sections were also taken to exclude the active infection. The patient's knee is pain-free with full range of motion after 3 years. The objective of this report was to highlight the importance of early diagnosis, prompt appropriate treatment of septic arthritis following arthroscopy and the awareness of the knee dislocation as a rare dreadful complication of postarthroscopic infection particularly in elderly patients.

Knee Dislocation in the Morbidly Obese Patient.

Though a relatively rare orthopedic injury, knee dislocation in the morbidly obese population has been increasingly reported in the literature. These injuries are often referred to as "ultralow-velocity knee dislocations" since they commonly occur after a seemingly trivial injury, such as a ground level fall. As a result, these injuries are often underappreciated and initially misdiagnosed. Even though these injuries are low-velocity, they should still be regarded as a high energy injury because of the large amount of mass contributing to the dislocating force. Knee dislocations in the morbidly obese are associated with a particularly high rate of neurovascular injury. A timely and accurate diagnosis is crucial to avoid serious limb-threatening complications, including the need for amputation. Therefore, evaluating physicians should maintain a high suspicion for a knee dislocation in any morbidly obese patient who presents with knee pain following a seemingly innocuous injury. Management of these injuries is controversial. Associated vascular injuries must be identified promptly and appropriately managed by a vascular surgery team. There is no consensus on the ideal orthopedic treatment of knee dislocations in the morbidly obese patient. Operative treatment can be fraught with complications, including a higher rate of neurovascular injury, increased surgical complications, and poor subjective patient outcome scores compared with nonobese patients sustaining a high-velocity knee dislocation. It is paramount that treating physicians are familiar with the unique challenges of treating knee dislocations in the morbidly obese patient when discussing risks and benefits of treatment options. This article presents a review of the existing literature on knee dislocations in the morbidly obese population, including diagnosis, management, and outcomes.

Extensor Mechanism Disruption in Knee Dislocation.

Disruption of the knee extensor mechanism is a challenging injury with no clear consensus on optimal treatment. Although rare in the setting of knee dislocations, these injuries should not be overlooked. Acute, complete rupture of either the quadriceps or patellar tendon necessitates primary repair with or without augmentation. Surgical management may also be required in the setting of a partial tear if a significant extensor lag is present or nonoperative treatment has failed. Tendon augmentation is used during primary repair if the native tissue is inadequate or after a failed primary repair. The purpose of this study is to evaluate extensor mechanism disruption incidence, injury patterns, associated injuries, and surgical options, including a novel tendon augmentation technique. This procedure consists of primary patellar or quadriceps tendon repair with semitendinosus autograft augmentation utilizing a distal or proximal patellar socket. Advantages of repair with tendon augmentation include accelerated rehabilitation, decreased risk of patellar fracture from transverse or longitudinal bone tunnels, and less hardware complications. We recommend consideration of this technique for selected cases of acute extensor mechanism disruption in the setting of tibiofemoral dislocation.

Computational modelling of mobile bearing TKA anterior-posterior dislocation.

Anterior-posterior stability in an unconstrained mobile-bearing total knee arthroplasty (TKA) and one with rotational constraints is compared in a computational model based on an ASTM test. Both TKA designs dislocate at loads greater than reported maximum in vivo forces. The posterior drawer forces (mean: 3027 N vs. 1817 N) needed to induce subluxation increase with a greater anterior jump distance (12 mm vs. 7 mm; refers to the vertical height of the anterior or posterior border of the tibial insert's articulating surface). The posterior jump distance for both tested TKA differed by 1.5 mm and had minimal effect on the magnitude of the anterior drawer forces at dislocation in mid-flexion (unconstrained vs. constrained: 445 N vs. 412 N). The unconstrained insert dislocated by means of spin-out whereas in the constrained TKA the femur dislocated from the bearing during posterior drawer and the bearing from the baseplate during anterior drawer. MCL function is an important consideration during ligament balancing since a ± 10% variation in MCL tension affects dislocation forces by ± 20%. The simulation platform provided the means to investigate TKA designs in terms of anterior-posterior stability as a function of knee flexion, collateral ligament function and mechanical morphology.

Pediatric Knee Dislocations and Physeal Fractures About the Knee.

Given the high incidence of vascular and neurologic injury associated with pediatric knee dislocations and displaced physeal injuries about the knee, a thorough understanding of the clinical and radiographic signs associated with these injuries, relevant anatomy, workup, reduction techniques, and surgical management is crucial. A higher incidence of these injuries in children is anticipated because of increased participation in high-energy activities that result in contact or collision during sports or recreation. Complications, such as vascular and nerve injuries and compartment syndrome, can be diagnosed early in the workup to prevent catastrophic outcomes. The clinical examination should include evaluation of the motor and sensory status of the limb, palpation of pulses, and measurement of ankle brachial indices. Radiographic examination should include plain radiography and supplemental advanced imaging, if indicated. Vascular imaging or expert consultation should be considered when the pulse or ankle brachial index is abnormal on clinical examination. Selection of nonsurgical or surgical treatment depends on the fracture pattern and stability.

Does age predict outcome after multiligament knee reconstruction for the dislocated knee? 2- to 22-year follow-up.

PURPOSE: The purpose of this study is to determine whether age is a predictor of clinical and functional outcomes in patients who sustained a knee dislocation (KD) and underwent multiligament knee reconstruction. It was hypothesized that increasing age will negatively affect patient outcome. METHODS: In total, 125 multiligament knee injuries (MLKI) associated with KD were surgically reconstructed between 1992 and 2013 and evaluated with IKDC and Lysholm scores at a median follow-up of 5 (range 2-22) years. Patient demographics including age were then analysed with respect to IKDC and Lysholm scores using rank sums and pair-wise rank sums analysis for continuous variables and Chi-square analysis for categorical variables. RESULTS: In total, 125 patients (96 males and 29 females) with a median age of 31 (range 11-62) years at the time of surgery were included. At final follow-up, patients ≤30 years old compared to >30 years old obtained higher IKDC (73.3 vs. 61.9; p = 0.01) and Lysholm scores (76.9 vs. 68.5; p = 0.04). No confounding variables including gender, injury mechanism, injury pattern, injuries to the peroneal nerve, popliteal artery, meniscus, or cartilage accounted for differences in outcome scores between the two groups. CONCLUSION: Based on current available literature, this study represents the largest cohort with the longest follow-up reported on MLKI to date. At intermediate- to long-term follow-up, patients >30 years of age that undergo multiligament knee reconstruction for KD have inferior IKDC and Lysholm scores compared to those ≤30 years of age. However, successful multiligament knee reconstruction can still be obtained in this age group. LEVEL OF EVIDENCE: IV.

Effect of anteromedial and posterolateral anterior cruciate ligament bundles on resisting medial and lateral tibiofemoral compartment subluxations.

PURPOSE: This study analyzed the interaction of the anteromedial and posterolateral portions of the anterior cruciate ligament (ACL) in resisting medial and lateral tibiofemoral compartment subluxations under multiple loading conditions. METHODS: By use of a 6-df robotic simulator, 10 human cadaveric knees were tested in 3 states: intact ACL, partial ACL (loss of either the anteromedial bundle [AMB] or posterolateral bundle [PLB]), and deficient ACL. The testing profile involved anterior-posterior translation and internal-external rotation, as well as 3 pivot-shift loading conditions with varying internal rotation torque (1- or 5-Nm) and coupled anterior force (35- or 100-N). Digitization of anatomic landmarks provided tibiofemoral compartment translations and centers of tibial rotation. RESULTS: During pivot-shift testing (100-N anterior force, 1-Nm internal rotation torque, and 7-Nm valgus), the lateral and medial compartment anterior translation increased by a mean of 2.5 ± 0.8 mm (P = .016) and 3.4 ± 2.0 mm (P = .001), respectively, on AMB sectioning and 1.3 ± 0.9 mm (P = .329) and 0.6 ± 0.7 mm (P = .544), respectively, on PLB sectioning. Higher internal rotation torque (5 Nm v 1 Nm) on pivot-shift testing reduced central and medial anterior translation after ACL sectioning. There was no change in internal rotation on AMB or PLB sectioning. During the Lachman test (100-N), AMB and PLB sectioning increased central translation by 3.6 ± 1.6 mm (P = .001) and 0.7 ± 0.6 mm (P = .498), respectively. CONCLUSIONS: Both ACL bundles function synergistically in resisting medial and lateral compartment subluxations on the Lachman and pivot-shift tests. The AMB provided more restraint to anterior tibial translation during both tests as compared with the PLB. PLB sectioning produced no statistically significant change in anterior translation on the Lachman or pivot-shift test. Neither bundle contributed to resisting internal rotation. CLINICAL RELEVANCE: An ACL graft designed to duplicate the AMB would theoretically resist medial and lateral compartment anterior subluxations under multiple loading conditions. The PLB provides a secondary restraint at low flexion angles. Neither ACL bundle resists internal tibial rotation or allows a positive pivot-shift subluxation.