Tobias M. Jung

A new quantitative method for pivot shift grading.

PurposeThe purposes of the study were to evaluate and to quantify the pivot shift phenomenon by using a small and easy to handle measuring device for pivot shift quantification.MethodsTwenty patients (forty knees) with primary torn anterior cruciate ligaments (ACL) were tested under anesthesia, graded by the examiner and by the device according to the IKDC classification [normal (0), glide (1), clunk (2), and gross (3)]. For the grading by the device, a femoral and a tibial miniature inertial sensor measured the acceleration and the angular velocities. Three parameters were used for pivot shift identification and quantification: (1) difference between the positive and negative acceleration peak value (adiff), (2) the maximum jerk (jmax), and (3) the standard deviation (SDa) of the acceleration. The ratio between the ACL-deficient and the intact knees was calculated in order to normalize the data.ResultsThe pivot shift phenomenon could be identified, and all three parameters showed significant higher values in the ACL-deficient knees compared to the intact knees (pxa0<xa00.05). The grading by examiner did not significantly correlate with adiff (pxa0=xa00.38; rxa0=xa00.21), jmax (pxa0=xa00.36; rxa0=xa0−0.22), SDa (pxa0=xa00.65; rxa0=xa00.11), and grading by the device (pxa0=xa00.62; rxa0=xa00.12).ConclusionsThe present study has shown that the quantification of the pivot shift test is practicable when inertial sensors are used. The results have shown that the subjective grading of the pivot shift test does not correlate well with objective quantification.

Prevalence of cartilage lesions and early osteoarthritis in patients with patellar dislocation

AbstractObjectivesAssessment of cartilage lesions and osteoarthritis (OA) of the patellofemoral joint in patients following lateral patellar dislocation using magnetic resonance imaging (MRI).MethodsMR images of 129 knees (mean age 26xa0years, range 11–56) grouped as acute (A), recurrent (B), and chronic (C) dislocators were analysed regarding the prevalence and severity of patellofemoral cartilage lesions. Grades of OA were assessed using modified WORMS.ResultsIn groups A, B, and C the prevalence of cartilage lesions was 71%, 82%, and 97%, respectively. Most lesions were located on the central patella in groups A and B (central 69% and 78%; medial 56% and 47%; lateral 31% and 42%), whereas group C revealed all regions affected (73%, 61%, and 67%). Of group A, 14% had mild OA and 64% of group B. Group C showed mild OA in 62% and moderate OA in 18%. Cartilage defect size and prevalence of OA was correlated with number of dislocations (ru2009=u20090.41 and ru2009=u20090.59; Pu2009<u20090.001).ConclusionsCartilage lesions and early OA are common after patellar dislocation and appear to increase with the frequency of dislocation. Both conditions should be considered when interpreting MRI in such patients, because of implications for treatment.Key Points• Cartilage lesions are very common after patellar dislocation.n • The severity of cartilage lesions increases with number of dislocations.n • Osteoarthritis is common after recurrent patellar dislocation, even in young patients.n • Detecting cartilage lesions is important after patellar dislocation.

Prevalence and patterns of anatomical risk factors in patients after patellar dislocation: a case control study using MRI

AbstractObjectiveTo assess anatomical risk factors in patients after lateral patellar dislocation (LPD) and controls using MRI.MethodsMR images of 186 knees after LPD and of 186 age- and gender-matched controls were analysed. The presence of trochlear dysplasia was assessed by evaluation of trochlear inclination, facet asymmetry, and trochlear depth; patella alta was evaluated by the Insall-Salvati index and Caton-Deschamps index; the lateralised force vector was measured by the tibial tuberosity-trochlear groove (TT-TG) distance.ResultsCompared with controls, dislocators had significantly lower values for all three parameters of trochlear dysplasia (−32xa0%, −32xa0%, −44xa0%) and significantly higher values for patella alta (+14xa0%,+13xa0%) and TT-TG (+49xa0%) (all Pu2009<u20090.001). Trochlear dysplasia was observed in 112 dislocators (66xa0%), of whom 61 (36xa0%) additionally had patella alta and 15 (9xa0%) an abnormal TT-TG. As isolated risk factors, patella alta (15xa0%) and abnormal TT-TG (1xa0%) were rare. Only 25 dislocators (15xa0%) had no anatomical risk factors. Trochlear dysplasia in conjunction with abnormal TT-TG or patella alta is associated with a 37- and 41-fold higher risk.ConclusionMost dislocators have anatomical risk factors, varying in severity and constellation.Key Points• Magnetic resonance imaging provides unique information about anatomical variation within the knee.n • Anatomical variants increase the risk for lateral patellar dislocation (LPD)n • Trochlear dysplasia is the main risk factor for LPD.n • Patellar alta and abnormal tibial tuberosity-trochlear groove distance may be additional factors.n • Patient-specific evaluation of risk factors following LPD may help future management.

Anterior Cruciate Ligament–Deficient Patients With Passive Knee Joint Laxity Have a Decreased Range of Anterior-Posterior Motion During Active Movements

Background: Although instability of the knee joint is known to modify gait patterns, the amount that patients compensate for joint laxity during active movements remains unknown. Purpose: By developing a novel technique to allow the assessment of tibiofemoral kinematics, this study aimed to elucidate the role of passive joint laxity on active tibiofemoral kinematics during walking. Study Design: Controlled laboratory study. Methods: Using motion capture, together with combinations of advanced techniques for assessing skeletal kinematics (including the symmetrical axis of rotation approach [SARA], symmetrical center of rotation estimation [SCoRE], and optimal common shape technique [OCST]), a novel noninvasive approach to evaluate dynamic tibiofemoral motion was demonstrated as both reproducible and repeatable. Passive and active anterior-posterior translations of the tibiofemoral joint were then examined in 13 patients with anterior cruciate ligament (ACL) ruptures that were confirmed by magnetic resonance imaging and compared with those in their healthy contralateral limbs. Results: Passive tibial anterior translation was significantly greater in the ACL-ruptured knees than in the contralateral healthy controls. However, the femora of the ACL-ruptured knees generally remained more posterior (~3 mm) relative to the tibia within a gait cycle of walking compared with the healthy limbs. Surprisingly, the mean range of tibiofemoral anterior-posterior translation over an entire gait cycle was significantly lower in ACL-ruptured knees than in the healthy joints (P = .026). A positive correlation was detected between passive laxity and active joint mobility, but with a consistent reduction in the range of tibiofemoral anterior-posterior translation of approximately 3 mm in the ACL-deficient knees. Conclusion: It seems that either active stabilization of tibiofemoral kinematics or anterior subluxation of the tibia reduces joint translation in lax knees. This implies that either a muscular overcompensation mechanism or a physical limitation due to secondary passive stabilizers occurs within the joint and thus produces a situation that has a reduced range of active motion compared with knees with physiological stability. Clinical Relevance: The reduced range of active tibiofemoral translation suggests overloading of the passive structures in passively lax knees, either through excessive muscular action or joint subluxation, and could provide a plausible mechanism for explaining posttraumatic degeneration of cartilage in the joint.

Reliable assessment of liver function using LiMAx

BACKGROUNDn(13)C-liver function breath tests can facilitate the assessment of hepatic function in-vivo and may help surgeons to identify candidates for safe liver surgery. However, their acceptance into clinical practice is dependent on evaluation of technical efficacy and repeatability. The aims of this study were to evaluate the within-subject repeatability of the LiMAx (maximum liver function capacity) test in healthy individuals and in surgical patients to determine liver function in the perioperative workup.nnnMATERIAL AND METHODSnThe LiMAx test, which is based on intravenous injection of (13)C-methacetin at a dosage of 2xa0mg/kg body weight was performed in eighty-six healthy subjects to determine a reference range. Twenty-four subjects underwent repeat LiMAx testing the following day to assess within-subject repeatability. Twenty-one patients undergoing elective extra-abdominal surgery under general anesthesia (GA group) received pre- and post-operative examinations.nnnRESULTSnThe normal range of LiMAx was found to be 430xa0±xa086xa0μg/kg/h and revealed a one-sided cut-off value of 315xa0μg/kg/h. The intraclass correlation coefficient of the repeat LiMAx tests was 0.85 (95% confidence interval 0.69-0.93) in the control group and 0.81 (95% confidence interval 0.60-0.92) in the group of patients with GA.nnnCONCLUSIONSnThe LiMAx test shows excellent reproducibility in subjects with normal liver function. GA has no effect on test results.

Knee Stability After Posterior Cruciate Ligament Reconstruction in Female Versus Male Patients: A Prospective Matched-Group Analysis

PURPOSEnTo analyze outcome differences after posterior cruciate ligament (PCL) reconstruction in male and female patients.nnnMETHODSnA prospective database of 234 PCL reconstructions (53 female and 181 male patients) with either isolated or combined procedures was analyzed. Patients were followed up for a mean of 62 months (range, 34 to 110 months) by use of stress radiography and the International Knee Documentation Committee score. We included 32 female patients for a matched-group analysis and compared them with 32 matching male patients. Matching parameters were number/type of reconstructed ligaments, revision/primary surgery, autograft/allograft use, preoperative tibial displacement, time interval from injury to surgery, follow-up interval, and age.nnnRESULTSnThere was no preoperative difference in posterior stress radiographs (12.9 ± 3.0 mm in female patients and 13.2 ± 2.3 mm in male patients). After surgery, both groups showed a significant reduction in posterior displacement (6.0 ± 2.5 mm [54% reduction] in female patients and 7.8 ± 2.2 mm [40% reduction] in male patients). There was a significant greater reduction of posterior laxity in female patients. International Knee Documentation Committee scoring showed a significant improvement in both groups.nnnCONCLUSIONSnWe found in this specific patient series a superior reduction of posterior tibial laxity in female patients compared with male patients, indicating that possible gender-related differences exist after PCL surgery.nnnLEVEL OF EVIDENCEnLevel III, retrospective comparative study using prospective data.

Osteochondral Lesions of the Talus: Retrograde Drilling with High-Field-Strength MR Guidance

The institutional review board approved the use of cadaveric specimens, and informed consent was obtained from all volunteers. The authors performed and assessed a magnetic resonance (MR)-assisted navigation method for minimally invasive retrograde drilling of talar osteochondral lesions. For this method, a single imaging plane is sufficient for navigation during intervention. To accomplish this objective, a passive MR navigation device was used to evaluate 16 cadaveric ankle joints. Use of this interactive MR-assisted navigation method in combination with a passive aiming device allowed precise and rapid retrograde drilling of talar osteochondral lesions.

Tibial Slope Strongly Influences Knee Stability After Posterior Cruciate Ligament Reconstruction: A Prospective 5- to 15-Year Follow-up

Background: The reported failure rate after posterior cruciate ligament (PCL) reconstruction remains high. Previous studies have shown that the tibial slope (TS) influences sagittal plane laxity. Consequently, alterations of TS might have an effect on postoperative knee stability after PCL reconstruction. Hypothesis: We hypothesized that flattening of TS is associated with increased posterior laxity after PCL reconstruction. Study Design: Cohort study; Level of evidence 3. Methods: This study consisted of 48 patients who underwent PCL reconstruction in a single-surgeon series. Eight patients underwent an isolated PCL reconstruction, 27 patients underwent an additional posterolateral corner reconstruction, and 13 patients underwent a combined reconstruction of the PCL, anterior cruciate ligament, and posterolateral corner. Three blinded observers measured TS and the side-to-side difference (SSD) of posterior tibial translation (PTT) before and after PCL reconstruction using standardized stress radiographs. The minimum follow-up was 5 years. Results: At a mean follow-up of 103 months (range, 65-187), the mean SSD of PTT was significantly reduced (10.9 ± 2.9 vs 4.9 ± 4.3 mm; P < .0001). The mean TS was 8.0° ± 3.7° (range, 1°-14.3°) for the operated knee and 7.9° ± 3.2° (range, 2°-15.3°) for the contralateral knee. There was a statistically significant correlation between TS and PTT (r = −0.77 and R2 = 0.59; P < .0001). In addition, there was a significant correlation between TS and the postoperative reduction of PTT (r = 0.74 and R2 = 0.55; P < .0001). Subgrouping according to the number of operated ligaments showed no significant differences regarding TS or the mean reduction of PTT. Conclusion: Flattening of TS is associated with a significantly higher remaining PTT as well as a lower reduction of PTT. Notably, these results are irrespective of sex and number of ligaments addressed. Thus, isolated soft tissue procedures in PCL deficiency may only incompletely address posterior knee instability in patients with flattening of the posterior slope.

Current concepts review: Fractures of the patella

Fractures of the patella account for about 1% of all skeletal injuries and can lead to profound impairment due to its crucial function in the extensor mechanism of the knee. Diagnosis is based on the injury mechanism, physical examination and radiological findings. While the clinical diagnosis is often distinct, there are numerous treatment options available. The type of treatment as well as the optimum timing of surgical intervention depends on the underlying fracture type, the associated soft tissue damage, patient factors (i.e. age, bone quality, activity level and compliance) and the stability of the extensor mechanism. Regardless of the treatment method an early rehabilitation is recommended in order to avoid contractures of the knee joint capsule and cartilage degeneration. For non-displaced and dislocated non-comminuted transverse patellar fractures (2-part) modified anterior tension band wiring is the treatment of choice and can be combined – due to its biomechanical superiority – with cannulated screw fixation. In severe comminuted fractures, open reduction and fixation with small fragment screws or new angular stable plates for anatomic restoration of the retropatellar surface and extension mechanism results in best outcome. Additional circular cerclage wiring using either typical metal cerclage wires or resorbable PDS/non-resorbable FiberWires increases fixation stability and decreases risk for re-dislocation. Distal avulsion fractures should be fixed with small fragment screws and should be protected by a transtibial McLaughlin cerclage. Partial or complete patellectomy should be regarded only as a very rare salvage operation due to its severe functional impairment.

Arthroscopic Treatment of Acute Tibial Avulsion Fracture of the Posterior Cruciate Ligament Using the TightRope Fixation Device

Avulsion fracture of the posterior cruciate ligament from its tibial insertion is a rare condition. Early surgical treatment has been regarded as necessary, but the optimal surgical technique remains unclear. The purpose of this technical note is to present a novel all-inside arthroscopic reconstruction technique for bony tibial avulsion fractures of the posterior cruciate ligament using the TightRope device (Arthrex, Naples, FL).