Eduardo M. Suero

The Effect of Proximal Tibial Slope on Dynamic Stability Testing of the Posterior Cruciate Ligament– and Posterolateral Corner–Deficient Knee

Background: Proximal tibial slope has been shown to influence anteroposterior translation and tibial resting point in the posterior cruciate ligament (PCL)–deficient knee. The effect of proximal tibial slope on rotational stability of the knee is unknown. Hypothesis: Change in proximal tibial slope produced via osteotomy can influence both static translation and dynamic rotational kinematics in the PCL/posterolateral corner (PLC)–deficient knee. Study Design: Controlled laboratory study. Methods: Posterior drawer, dial, and mechanized reverse pivot-shift (RPS) tests were performed on hip-to-toe specimens and translation of the lateral and medial compartments measured utilizing navigation (n = 10). The PCL and structures of the PLC were then sectioned. Stability testing was repeated, and compartmental translation was recorded. A proximal tibial osteotomy in the sagittal plane was then performed achieving either +5° or −5° of tibial slope variation, after which stability testing was repeated (n = 10). Analysis was performed using 1-way analysis of variance (ANOVA; α = .05). Results: Combined sectioning of the PCL and PLC structures resulted in a 10.5-mm increase in the posterior drawer, 15.5-mm increase in the dial test at 30°, 14.5-mm increase in the dial test at 90°, and 17.9-mm increase in the RPS (vs intact; P < .05). Increasing the posterior slope (high tibial osteotomy [HTO] +5°) in the PCL/PLC-deficient knee reduced medial compartment translation by 3.3 mm during posterior drawer (vs deficient; P < .05) but had no significant effect on the dial test at 30°, dial test at 90°, or RPS. Conversely, reversing the slope (HTO −5°) caused a 4.8-mm increase in medial compartment translation (vs deficient state; P < .05) during posterior drawer and an 8.6-mm increase in lateral compartment translation and 9.0-mm increase in medial compartment translation during RPS (vs deficient state; P < .05). Conclusion: Increasing posterior tibial slope diminished static posterior instability of the PCL/PLC-deficient knee as measured by the posterior drawer test but had little effect on rotational or dynamic multiplanar stability as assessed by the dial and RPS tests, respectively. Conversely, decreasing posterior slope resulted in increased posterior instability and a significant increase in the magnitude of the RPS. Clinical Relevance: These results suggest that increasing posterior tibial slope may improve sagittal stability in the PCL/PLC-deficient knee. Moreover, a knee with diminished posterior tibial slope may demonstrate greater multiplanar instability in this setting. Consequently, proximal tibial slope should be considered when treating combined PCL/PLC injuries of the knee.

Risk factors for heterotopic ossification in patients with spinal cord injury: a case-control study of 264 patients.

Study Design. Case-control study. Objective. We designed a case-control study to analyze the risk factors associated with the development of heterotopic ossification (HO) in patients with traumatic spinal cord injury. Summary of Background Data. Patients with spinal cord injury have a high risk of developing HO, although the exact etiopathogenesis is still unknown. Several factors are known to be potential risk factors. However, we are not aware of any large clinical studies evaluating the risk factors for HO. Methods. Patients who were treated for a traumatic spinal cord injury in our hospital, and who subsequently developed HO, were identified by querying the electronic database at our hospital from 2002 to 2010. One hundred thirty-two patients and 132 controls were included. Our primary outcome measures were the risk of developing HO according to whether the patient had experienced a complete spinal cord lesion according to American Spinal Injury Association Impairment Scale; tetraplegia or paraplegia; cervical, thoracic, or lumbar injury; severe chest trauma; and the time interval between injury and surgery. Secondary risk factors explored were patient age; sex; presence and number of comorbidities; length of hospital and intensive care unit stay; associated traumatic injuries; presence of spasticity, pressure ulcers, deep venous thrombosis, and urinary tract infection; and pulmonary complications, such as pneumonia and necessity of tracheostomy. Results. Patients with associated spasticity and thoracic trauma, complete lesion, pneumonia, presence of tracheostomy, and urinary tract infection had a higher risk of developing HO. Conclusion. Adequate management of potential risk factors could help reduce the overall incidence of HO and outcome in patients with traumatic spinal cord injury.

Use of a virtual 3D software for planning of tibial plateau fracture reconstruction.

OBJECTIVE Anatomical reconstruction of tibial plateau fractures is necessary to prevent pain, axial malalignment, knee join instability and posttraumatic arthritis. Computed tomography (CT) with 3D reconstruction is helpful in the accurate preoperative evaluation and reduction planning of the fracture site. The aim of this study was to describe the application of a virtual 3D reconstruction and segmentation software in the preoperative planning of tibial plateau fractures. PATIENTS AND METHODS CT scans of five tibial plateau fractures were preoperatively evaluated using the 3D planning software. Manual colour-coded segmentation was performed. The amount of time required for each planning session was recorded. RESULTS Successful 3D reconstruction and segmentation was achieved in all cases. The mean time required for 3D virtual planning was 174.8 min (range 69-124 min). The mean time required for 3D virtual planning of B-type fractures was 96.5 min (range 69-124 min; SD=38.891 min; CI=349.421). The mean time required for planning of C-type fractures was 227 min (range 167-294 min; SD=63.789 min; CI=158.460) (Table 1). CONCLUSION Successful segmentation was achieved in all cases. The 3D planning capabilities of this software may be a valuable tool for surgeons in learning about the nature of the injury in tibial plateau fracture cases and in formulating an appropriate surgical plan. However, the time requirement for the 3D reconstruction and segmentation analysis may be a current deterrent for its use in the clinical setting.

Effect of Femoral Socket Position on Graft Impingement After Anterior Cruciate Ligament Reconstruction

Background: Despite improved biomechanical stability and kinematics with anatomic anterior cruciate ligament (ACL) reconstruction, concerns regarding notch impingement of the graft have persisted, particularly with increasingly anterior tibial tunnel position. The potentially mitigating effect of anatomic femoral socket position, however, has not been evaluated. Hypothesis: Placement of the femoral socket in the central or posterolateral bundle footprint reduces the risk and magnitude of graft impingement after ACL reconstruction compared with placement in the anteromedial bundle footprint. Study Design: Controlled laboratory study. Methods: This study employed computer-assisted navigation in a cadaveric model to evaluate the effect of tibial and femoral tunnel position on ACL graft impingement. Sixteen cadaveric knees were tested using the Praxim ACL Surgetics Navigation System, with the tibial tunnel positioned in the footprint of the anteromedial bundle and the femoral socket placed in the (1) anteromedial bundle footprint, (2) center of footprint, or (3) posterolateral bundle footprint. The amount of maximum impingement, angle of initial impingement, and location of graft impingement were documented through a full arc of knee motion. Results: Impingement occurred with all 3 femoral socket positions, but the mean angle of impingement with the anteromedial femoral position (42.8° ± 26.4°) was significantly greater (P < .003) than the mean angles of impingement with the central femoral position (19.4° ± 19.2°) and the posterolateral bundle femoral position (16.7° ± 13.3°). Conclusion: Although notch impingement was seen in all femoral socket locations with an anteromedial tibial socket position, femoral socket position in a central or posterolateral bundle location may reduce the risk and magnitude of graft impingement after ACL reconstruction. Additional studies are necessary to determine the influence of these different constructs on graft isometry and knee kinematics. Clinical Relevance: Anatomic femoral socket position in the center of the native ACL footprint may reduce the risk and magnitude of notch impingement compared with an anteromedial bundle position with ACL reconstruction.

Effects of tibial slope changes in the stability of fixed bearing medial unicompartmental arthroplasty in anterior cruciate ligament deficient knees

Patients with anterior cruciate ligament (ACL) deficiency may have increased failure rates with UKA as a result of abnormal contact stresses and altered knee kinematics. Variations in the slope of the tibial component in UKA may alter tibiofemoral translation, and affect outcomes. This cadaveric study evaluated tibiofemoral translation during the Lachman and pivot shift tests after changing the slope of a fixed bearing unicondylar tibial component. Sectioning the ACL increased tibiofemoral translation in both the Lachman and pivot shift tests (P<0.05). Tibial slope leveling (decreasing the posterior slope) of the polyethylene insert in a UKA decreases anteroposterior tibiofemoral translation in the sagittal plane to a magnitude similar to that of the intact knee. With 8° of tibial slope leveling, anterior tibial translation during the Lachman test decreased by approximately 5mm. However, no variation in slope altered the pivot shift kinematics in the ACL deficient knees.

Stability of the metatarsophalangeal joint of the lesser toes: a cadaveric study.

Dorsal instability of the metatarsophalangeal joint (MTPJ) of the lesser toes is an important cause of forefoot pain. Both conservative and surgical treatment options have been proposed. However, the role of each static stabilizing structure has not been elucidated. We hypothesized that isolated sectioning of the plantar plate (PP) would result in greater dorsal translation compared to isolated sectioning of the medial collateral ligaments (MCL) or lateral (LCL) collateral ligaments, or the extensor hood (EH), and that combined injury to two or more structures would result in greater dorsal translation compared to isolated PP injury. Fifty‐four cadaveric lesser toe specimens were randomized into groups for individual and combined sectioning of the PP, EH, and LCL and MCL. A 30 N axial load was applied to each specimen in the plantar–dorsal direction and dorsal translation of the phalanx was measured for each condition. ANOVA was used to compare groups. A 19% change in MTP translation was found from intact after sectioning the PP. No significant difference in translation was seen after individual sectioning of the EH, MCL, or LCL. A significant increase in translation occurred from intact with the following sectioning combinations: MCL + LCL, 37%; EH + MCL + LCL, 45%; and PP + MCL + LCL, 63%. Thus, the PP is the main restraint for dorsal MTPJ translation. MCL and LCL have important partial contribution to MTPJ stability. Injury to the PP, individually, or combined injuries to the PP, EH, MCL, or LCL, appear to cause significant instability that may warrant more aggressive treatment.

Range of motion assessment of the shoulder and elbow joints using a motion sensing input device: a pilot study.

BACKGROUND Motion sensing input devices could provide a practical and low-cost alternative method for repeated range of motion measurements. This study aimed to assess the reliability, accuracy and time requirements of a motion sensing input device (Microsoft Kinect) for ROM measurements comparing it with goniometer based measurements and subjective estimation. MATERIAL AND METHODS Full ROM was measured in 14 shoulder and elbow joints using the different methods. The order was randomly selected and each movement was measured twice. The results were recorded in degrees and the time measured in seconds. RESULTS In general, there was a poor to moderate agreement between the Kinect system compared to the goniometer. There was a good agreement between the goniometer-based and the subjective technique. The Kinect-based technique showed excellent test-retest reliability. CONCLUSION The Kinect system showed good test-retest reliability, but lower accuracy compared to goniometer-based measurements. Improvements in patient positioning and measurement protocol standardization must be made before its implementation in clinical practice.

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.

Clinical Tips: Retrograde Drilling Of Talar Osteochondral Defects

Contemporary methods of bone grafting osteochondral defects, in which the remaining overlying cartilage is relatively well preserved, have inherent problems. The bony defects are often saucer-shaped and the cylindrical graft may not fill the void, leaving areas of cartilage with no underlying scaffold and obviating early weight bearing. Furthermore, to obtain a proper fill of the defect, tamping of the graft can cause excessive pressure and disruption of the overlying cartilage. In an effort to address these concerns, the authors propose the use of a biological viscous paste of calcium sulfate that hardens within 5 minutes when injected in a retrograde fashion into the talus. This confers a mechanical advantage of complete cystic fill of the cyst which allows early weight bearing. Calcium sulfate acts as an osteoconductive material that incorporates into host bone within 8 weeks. Donor site morbidity is eliminated using this system.

The Anatomic Basis for the Arthroscopic Latarjet Procedure A Cadaveric Study

Background: The Latarjet technique is a reliable treatment option for recurrent anterior shoulder instability. However, the complication rate has been reported to be as high as 30%, with 1.6% of patients suffering a nerve injury. The all-arthroscopic Latarjet procedure has been gaining popularity, even as it has introduced its own challenges. Given that the surgeon is not able to palpate the nerves, their localization and protection can be difficult. Additionally, the use of different instruments can lead to distinct nerve injury mechanisms. Purpose: To describe the anatomic trajectory of the musculocutaneous, axillary, and suprascapular nerves in relation to the arthroscopic Latarjet approach. Using this information, guidance is provided for reducing nerve injuries during instrumentation and screw insertion. Study Design: Descriptive laboratory study. Methods: A total of 50 cadaveric shoulders from 25 whole-body specimens were examined. The specimens were placed in the beach-chair position, and the deltopectoral and dorsal approaches were used to expose the relevant structures. A subscapularis muscle split was performed between the inferior and middle thirds of the tendon. Digital caliper measurements were taken between various points of the trajectories of the nerves and surrounding anatomic landmarks. The location of the nerves relative to the split was recorded. Results: The musculocutaneous nerve lay within the split in 66% of the shoulders (n = 33); it was medial to the split in 28% (n = 14); it was found lateral to split in 2% (n = 1); and it was not identified in 4% of shoulders (n = 2). The mean length of the axillary nerve was 4.0 cm (95% CI, 3.7-4.2) from the exit of the plexus to the quadrangular space. The axillary nerve was found to be within the split in 50% of the shoulders (n = 25) and medial to the split in the remaining 50% (n = 25). The suprascapular nerve at the level of the supraspinatous fossa passed 3.3 cm (95% CI, 3.1-3.5) medial to the superior rim of the posterior glenoid. The nerve curves around the root of the spine at the spinoglenoid notch level, approximating the glenoid rim to a distance of 2.1 cm (95% CI, 2.0-2.2). Finally, the nerve runs medially again before branching out into smaller fibers to innervate the infraspinatus muscle at a distance of 2.9 cm (95% CI, 2.7-3.1) from the inferior glenoid rim. Based on these findings, there is an approximately 2 cm–wide safe zone from the edge of the glenoid rim for the insertion of graft-fixing screws. Conclusion: When performing a subscapularis split in the arthroscopic Latarjet procedure, the risk of injuries to the musculocutaneous and axillary nerves could be reduced by aiming the switching stick inserted through the posterior portal toward the lateral edge of the intended location of the split. Injuries to the suprascapular nerve could be prevented by aiming the graft-fixing screws laterally toward the edge of the glenoid rim. Clinical Relevance: This study clarifies the location of the nerves relevant to the arthroscopic Latarjet technique and provides anatomic information that could help the surgeon reduce the risk of injuries to the musculocutaneous, axillary, and suprascapular nerves.