Daniel Guenther

Structural Properties of the Anterolateral Capsule and Iliotibial Band of the Knee

Background: The role of the anterolateral capsule in knee stability has recently been advocated by studies reporting that a distinct ligament exists in this area. Defining the structural properties of the anterolateral capsule can provide insight into its contribution to joint stability. The structural properties of the iliotibial band also need to be determined, as it is a common graft used for extra-articular tenodesis. Purpose/Hypothesis: The purpose of this study was to determine the structural properties of the anterolateral capsule and iliotibial band. The hypothesis was that the iliotibial band will have comparable structural properties to the anterolateral capsule because it is generally an accepted graft for extra-articular reconstruction surgeries. Study design: Controlled laboratory study. Methods: Nine human cadaveric knees (average age, 57 ± 10 years) were dissected to assess the presence of a discrete capsular thickness originating from the lateral femoral epicondyle to the lateral tibial plateau between the Gerdy tubercle and the fibular head. For each knee, 2 constructs were prepared: (1) a bone–anterolateral capsule–bone specimen and (2) a strip of iliotibial band attached to the Gerdy tubercle. Structural properties, including ultimate load, ultimate elongation, and stiffness, were determined for the anterolateral capsule and the iliotibial band. After tensile testing, plain radiographs were obtained for evaluation of the Segond fracture. A paired t test was used to compare the structural properties of the anterolateral capsule with the iliotibial band. Significance was set at P < .05. Results: Two of the 9 specimens were found to have a discrete thickening of the anterolateral capsule. The iliotibial band had almost 50% higher ultimate load and nearly 3 times higher stiffness (487.9 ± 156.9 N and 73.2 ± 24.1 N/mm, respectively) compared with the anterolateral capsule (319.7 ± 212.6 N and 26.0 ± 11.5 N/mm, respectively) (P < .05 for both). The anterolateral capsule had about double the ultimate elongation compared with the iliotibial band (15.5 ± 7.3 and 8.6 ± 1.4 mm, respectively; P < .05). Conclusion: The anterolateral capsule demonstrated significantly reduced structural properties compared with the iliotibial band. The anterolateral capsule did not have a higher ultimate load compared with the posteromedial capsule as reported in the literature. Clinical Relevance: The decision to perform an extra-articular reconstruction using an iliotibial band graft should be considered carefully. Unnecessary reconstructions using soft tissue grafts with structural properties that far exceed that of the anterolateral capsule may result in overconstraint of the ACL-reconstructed knee.

Anterolateral ligament of the knee, fact or fiction?

however, an anterolateral ligament (ALL) was never seen in any of the examined species. This suggests a negative selection against this feature in our own evolution. We have also dissected several fetuses aged 18–22 weeks, and again no distinguishable anterolateral ligament was identified within the capsule. When evaluating the macroscopic anatomy, histology and radiology of the anterolateral capsule in adult human cadaveric specimens, only 30 % of the specimens showed a discrete capsular thickening of 2–4 mm on magnetic resonance imaging (MRI), much thinner than, for example, the LCL. During arthroscopic trans-illumination of these same specimens, no thickening of the anterolateral capsule was seen. Interestingly, on further analysis, internal rotation and flexion of the knee caused a fold in the anterolateral capsule, mimicking a thickening. Histology of this capsular thickening was performed and compared with that of the LCL. The LCL showed a clear linear alignment of collagen fibres, while the anterolateral capsule showed some alignment but not pronounced enough to constitute a true ligament [3]. In our experience of evaluating the anatomy of the anterolateral capsule in more than 150 patients with an A heated debate is ongoing regarding the anatomy of the anterolateral capsule of the knee. Current literature provides a multitude of descriptions. Researchers have argued that the capsule contains a true ligament, while others suggest it merely displays a thickening; yet others fail to show any distinguishable capsular structures. Given the recent surge in the literature on the anterolateral capsule of the knee, it is of great importance to be meticulous in evaluating every aspect of it, including the anatomy, histology, biomechanics, kinematics and clinical implication prior to recommending on its repair or reconstruction. While performing anatomic dissections on 24 different animal species, we have consistently found a double lateral collateral ligament (LCL) in three types of primates;

Anterolateral rotatory instability of the knee.

AbstractRecent publications have generated renewed interest in the anatomy of the anterolateral capsule. Knowledge of the biomechanical function of the anterolateral components is lacking. Further research is required to evaluate the influence of the anterolateral capsule on rotatory laxity of the knee. The role of surgical procedures, such as an extra-articular tenodesis or lateral plasty, has to be defined based on quantification of the injury. This article seeks to summarize the current literature and discusses the role of the anterolateral capsule and reconstructive techniques in combined ligamentous knee trauma. Level of evidence V.

Synovial C-reactive protein as a marker for chronic periprosthetic infection in total hip arthroplasty

The aim of this study was to assess the role of synovial C-reactive protein (CRP) in the diagnosis of chronic periprosthetic hip infection. We prospectively collected synovial fluid from 89 patients undergoing revision hip arthroplasty and measured synovial CRP, serum CRP, erythrocyte sedimentation rate (ESR), synovial white blood cell (WBC) count and synovial percentages of polymorphonuclear neutrophils (PMN). Patients were classified as septic or aseptic by means of clinical, microbiological, serum and synovial fluid findings. The high viscosity of the synovial fluid precluded the analyses in nine patients permitting the results in 80 patients to be studied. There was a significant difference in synovial CRP levels between the septic (n = 21) and the aseptic (n = 59) cohort. According to the receiver operating characteristic curve, a synovial CRP threshold of 2.5 mg/l had a sensitivity of 95.5% and specificity of 93.3%. The area under the curve was 0.96. Compared with serum CRP and ESR, synovial CRP showed a high diagnostic value. According to these preliminary results, synovial CRP may be a useful parameter in diagnosing chronic periprosthetic hip infection.

The Anterolateral Capsule of the Knee Behaves Like a Sheet of Fibrous Tissue

Background: The function of the anterolateral capsule of the knee has not been clearly defined. However, the contribution of this region of the capsule to knee stability in comparison with other anterolateral structures can be determined by the relative force that each structure carries during loading of the knee. Purpose/Hypothesis: The purpose of this study was to determine the forces in the anterolateral structures of the intact and anterior cruciate ligament (ACL)–deficient knee in response to an anterior tibial load and internal tibial torque. It was hypothesized that the anterolateral capsule would not function like a traditional ligament (ie, transmitting forces only along its longitudinal axis). Study Design: Controlled laboratory study. Methods: Loads (134-N anterior tibial load and 7-N·m internal tibial torque) were applied continuously during flexion to 7 fresh-frozen cadaveric knees in the intact and ACL-deficient state using a robotic testing system. The lateral collateral ligament (LCL) and the anterolateral capsule were separated from the surrounding tissue and from each other. This was done by performing 3 vertical incisions: lateral to the LCL, medial to the LCL, and lateral to the Gerdy tubercle. Attachments of the LCL and anterolateral capsule were detached from the underlying tissue (ie, meniscus), leaving the insertions and origins intact. The force distribution in the anterolateral capsule, ACL, and LCL was then determined at 30°, 60°, and 90° of knee flexion using the principle of superposition. Results: In the intact knee, the force in the ACL in response to an anterior tibial load was greater than that in the other structures (P < .001). However, in response to an internal tibial torque, no significant differences were found between the ACL, LCL, and forces transmitted between each region of the anterolateral capsule after capsule separation. The anterolateral capsule experienced smaller forces (~50% less) compared with the other structures (P = .048). For the ACL-deficient knee in response to an anterior tibial load, the force transmitted between each region of the anterolateral capsule was 434% greater than was the force in the anterolateral capsule (P < .001) and 54% greater than the force in the LCL (P = .036) at 30° of flexion. In response to an internal tibial torque at 30°, 60°, or 90° of knee flexion, no significant differences were found between the force transmitted between each region of the anterolateral capsule and the LCL. The force in the anterolateral capsule was significantly smaller than that in the other structures at all knee flexion angles for both loading conditions (P = .004 for anterior tibial load and P = .04 for internal tibial torque). Conclusion: The anterolateral capsule carries negligible forces in the longitudinal direction, and the forces transmitted between regions of the capsule were similar to the forces carried by the other structures at the knee, suggesting that it does not function as a traditional ligament. Thus, the anterolateral capsule should be considered a sheet of tissue. Clinical Relevance: Surgical repair techniques for the anterolateral capsule should restore the ability of the tissue to transmit forces between adjacent regions of the capsule rather than along its longitudinal axis.

Validation of Quantitative Measures of Rotatory Knee Laxity.

Background: Prior attempts to quantify the pivot-shift examination have been too invasive or impractical for clinical use. A noninvasive method for quantifying rotatory knee laxity is needed. Hypothesis: Greater quantitative measurements of rotatory knee laxity (both of the involved knee as well as compared with the contralateral healthy knee) are associated with an increasing clinical pivot-shift grade. Study Design: Cross-sectional study; Level of evidence, 3. Methods: A total of 103 patients undergoing anatomic single-bundle anterior cruciate ligament (ACL) reconstruction at 4 international centers underwent a standardized pivot-shift test preoperatively on both knees while anesthetized. Clinical grading of the pivot shift was performed according to the International Knee Documentation Committee (IKDC) knee ligament rating system. Two different quantitative technologies were used to measure rotatory knee laxity: an inertial sensor and an image analysis were independently used to measure tibial acceleration and lateral compartment translation, respectively, during the pivot-shift test. Patients were dichotomized to “high-grade” (abnormal and severely abnormal) or “low-grade” (normal and nearly normal) rotatory knee laxity groups based on the clinical pivot-shift test result of the involved side. Tibial acceleration and lateral compartment translation of the involved knee and the side-to-side difference between the involved and contralateral knees were separately compared between the high- and low-grade rotatory knee laxity groups utilizing t tests; significance was set at P < .05. Results: Forty-three patients were in the low-grade rotatory knee laxity group, and 60 patients were in the high-grade rotatory knee laxity group. Patients in the high-grade knee laxity group had significantly higher lateral compartment translation as measured with the image analysis (involved knee: 3.8 ± 2.3 mm; side-to-side difference: 2.5 ± 2.4 mm) compared with patients in the low-grade group (involved knee: 2.0 ± 1.4 mm; side-to-side difference: 1.4 ± 1.5 mm) (both P < .01). As measured with the inertial sensor, tibial acceleration for patients in the high-grade group was significantly higher (involved knee: 7.2 ± 5.3 m/s2; side-to-side difference: 4.2 ± 5.4 m/s2) compared with patients in the low-grade group (involved knee: 4.2 ± 1.6 m/s2; side-to-side difference: 1.2 ± 1.2 m/s2) (both P < .01). Conclusion: The inertial sensor and image analysis techniques were able to detect differences between low- and high-grade pivot-shift test results. A quantitative assessment of the pivot-shift test could augment the diagnosis of an ACL injury and improve the ability to detect changes in rotatory knee laxity over time.

Overweight and obesity in hip and knee arthroplasty: Evaluation of 6078 cases

AIM To evaluate a possible association between the various levels of obesity and peri-operative charac-teristics of the procedure in patients who underwent endoprosthetic joint replacement in hip and knee joints. METHODS We hypothesized that obese patients were treated for later stage of osteoarthritis, that more conservative implants were used, and the intra-and perioperative complications increased for such patients. We evaluated all patients with body mass index (BMI) ≥ 25 who were treated in our institution from January 2011 to September 2013 for a primary total hip arthroplasty (THA) or total knee arthroplasty (TKA). Patients were split up by the levels of obesity according to the classification of the World Health Organization. Average age at the time of primary arthroplasty, preoperative Harris Hip Score (HHS), Hospital for Special Surgery score (HSS), gender, type of implanted prosthesis, and intra-and postoperative complications were evaluated. RESULTS Six thousand and seventy-eight patients with a BMI ≥ 25 were treated with a primary THA or TKA. Age decreased significantly (P < 0.001) by increasing obesity in both the THA and TKA. HHS and HSS were at significantly lower levels at the time of treatment in the super-obese population (P < 0.001). Distribution patterns of the type of endoprostheses used changed with an increasing BMI. Peri- and postoperative complications were similar in form and quantity to those of the normal population. CONCLUSION Higher BMI leads to endoprosthetic treat-ment in younger age, which is carried out at significantly lower levels of preoperative joint function.

Preliminary Results of a New Test for Rapid Diagnosis of Septic Arthritis with Use of Leukocyte Esterase and Glucose Reagent Strips

BACKGROUND Most currently used tools to diagnose septic arthritis are either not readily available or fail to provide real-time results. Reagent strip tests have identified infections in various body fluids. We hypothesized that combined leukocyte esterase and glucose strip tests can aid in diagnosing septic arthritis in native synovial fluid because (1) leukocyte esterase concentrations would be elevated at the infection site because of secretion by recruited neutrophils, and (2) glucose concentrations would be reduced because of bacterial metabolism. METHODS We prospectively investigated synovial fluid from consecutive patients with an atraumatic joint effusion who underwent arthrocentesis in our emergency department during a one-year period. Leukocyte esterase and glucose strip tests were performed on the synovial fluid. Synovial fluid leukocyte count, crystal analysis, Gram staining, culture, and glucose concentration results were also assessed. RESULTS Nineteen fluids were classified as septic and 127 as aseptic. Considering septic arthritis to be present when the leukocyte esterase reading was positive (++ or +++) and the glucose reading was negative (-) yielded a sensitivity of 89.5% (95% confidence interval [CI], 66.9% to 98.7%), specificity of 99.2% (95% CI, 95.7% to 99.9%), positive predictive value of 94.4% (95% CI, 72.7% to 99.9%), negative predictive value of 98.4% (95% CI, 94.5% to 99.8%), positive likelihood ratio of 114, and negative likelihood ratio of 0.11. The synovial leukocyte counts and polymorphonuclear cell percentages were consistent with the semiquantitative readings on the leukocyte esterase strip tests, and the glucose concentrations were consistent with the glucose strip test results. CONCLUSIONS Combined leukocyte esterase and glucose strip tests can be a useful additional tool to help confirm or rule out a diagnosis of septic arthritis.

Fungal periprosthetic joint infection in total knee arthroplasty: a systematic review.

Fungal periprosthetic joint infection (PJI) is a rare but devastating complication following total knee arthroplasty (TKA). A standardized procedure regarding an accurate treatment of this serious complication of knee arthroplasty is lacking. In this systematic review, we collected data from 36 studies with a total of 45 reported cases of a TKA complicated by a fungal PJI. Subsequently, an analysis focusing on diagnostic, medicaments and surgical procedures in the pre-, intra- and postoperative period was performed. Candida spp. accounts for about 80% (36 out of 45 cases) of fungal PJIs and is therefore the most frequently reported pathogen. A systemic antifungal therapy was administered in all but one patient whereas a local antifungal therapy, e.g. the use of an impregnated spacer, is of inferior relevance. Resection arthroplasty with delayed re-implantation (two-stage revision) was the surgical treatment of choice. However, in 50% of all reported cases the surgical therapy was heterogeneous. The outcome under a combined therapy was moderate with recurrent fungal PJI in 11 patients and subsequent bacterial PJI as a main complication in 5 patients. In summary, this systematic review integrates data from up to date 45 reported cases of a fungal PJI of a TKA. On the basis of the current literature strategies for the treatment of this devastating complication after TKA are discussed.

Correlation between a 2D simple image analysis method and 3D bony motion during the pivot shift test

BACKGROUND The pivot shift test is the most specific clinical test to detect anterior cruciate ligament injury. The purpose of this study was to determine the correlation between the 2D simple image analysis method and the 3D bony motion of the knee during the pivot shift test and assess the intra- and inter-examiner agreements. METHODS Three orthopedic surgeons performed three trials of the standardized pivot shift test in seven knees. Two devices were used to measure motion of the lateral knee compartment simultaneously: 1) 2D simple image analysis method: translation was determined using a tablet computer with custom motion tracking software that quantified movement of three markers attached to skin over bony landmarks; 2) 3D bony motion: electromagnetic tracking system was used to measure movement of the same bony landmarks. RESULTS The 2D simple image analysis method demonstrated a good correlation with the 3D bony motion (Pearson correlation: 0.75, 0.76 and 0.79). The 3D bony translation increased by 2.7 to 3.5 times for every unit increase measured by the 2D simple image analysis method. The mean intra-class correlation coefficients for the three examiners were 0.6 and 0.75, respectively for 3D bony motion and 2D image analyses, while the inter-examiner agreement was 0.65 and 0.73, respectively. CONCLUSIONS The 2D simple image analysis method results are related to 3D bony motion of the lateral knee compartment, even with skin artifact present. This technique is a non-invasive and repeatable tool to quantify the motion of the lateral knee compartment during the pivot shift test.