Lorenz Büchler

Reliability of radiologic assessment of the fracture anatomy at the posterior tibial plafond in malleolar fractures

Objectives: The aim of this study was to assess the ability to extract surgically relevant information from plain radiographs in trimalleolar fractures and to compare this with the information gathered from computed tomography (CT). Design: Retrospective analysis of consecutive patients. Setting: Level 1 trauma center. Patients: Retrospective analysis of the records of 22 patients with trimalleolar fractures treated at our institution between 1996 and 2006. Inclusion criteria were a complete radiographic documentation including plain anteroposterior and lateral radiographs and a preoperative CT scan of the ankle joint. Intervention: The radiographs of the included patients were evaluated twice within 3 months by 8 experienced orthopaedic trauma surgeons. The following criteria were analyzed: the presence or absence of a fracture in the posteromedial corner of the tibial plafond, loose posterior osteochondral fragments, impaction of posterior osteochondral fragments on the anteroposterior and the lateral radiographs, and size of the posterolateral fragment as percentage of the articular surface in the capital diameter of the tibial plafond. The results were compared with the CT scans. Results: All parameters showed a poor to fair reproducibility, reliability, and accuracy except the size of the posterior fragment, where good correlations were achieved. Conclusions: Only the extent of the posterior fragment can be measured reliably, reproducibly, and accurately on plain radiographs. Comminution and impaction of the posterior fracture are underestimated by far. Surgically relevant information is missed, which can lead to intraoperative inability to properly reduce the fracture. Preoperative CT evaluation is recommended in all patients with trimalleolar fractures, independent of the size of the posterior fragment.

Arthroscopic Versus Open Cam Resection in the Treatment of Femoroacetabular Impingement

PURPOSE The purpose of this study was to evaluate if osseous correction of the femoral neck achieved arthroscopically is comparable to that achieved by surgical dislocation. METHODS We retrospectively analyzed all patients who were treated with hip arthroscopy or surgical dislocation for cam or mixed type femoroacetabular impingement (FAI) in our institution between 2006 and 2009. Inclusion criteria were complete clinical and radiologic documentation with standardized radiographs. Group 1 consisted of 66 patients (49 female patients, mean age 33.8 years) treated with hip arthroscopy. Group 2 consisted of 135 patients (91 male patients, mean age 31.2 years) treated with surgical hip dislocation. We compared the preoperative and postoperative alpha and gamma angles, as well as the triangular index. Mean follow-up was 16.7 months (range, 2 to 79 months). RESULTS In group 1, the mean alpha angle improved from 60.7° preoperatively to 47.8° postoperatively (P < .001) and the mean gamma angle improved from 47.3° to 44.5° (P < .001). Over time, the preoperative mean alpha angle increased from 56.3° in 2006 to 67.5° in 2009, whereas the postoperative mean alpha angle decreased from 51.2° in 2006 to 47.5° in 2009. In group 2, the mean alpha angle improved from 75.3° preoperatively to 44.8° postoperatively (P < .001), and the mean gamma angle improved from 65.1° to 52.2° (P < .001). Arthroscopic revision of intra-articular adhesions was performed in 4 patients (6.1%) in group 1 and 16 patients (12%) in group 2. Three patients (2.2%) in group 2 underwent revision for nonunion of the greater trochanter. CONCLUSIONS Osseous correction of cam-type FAI with hip arthroscopy is comparable to the correction achieved by surgical hip dislocation. There is a significant learning curve for hip arthroscopy, with postoperative osseous correction showing improved results with increasing surgical experience. LEVEL OF EVIDENCE Level III, retrospective comparative study.

Pelvic Morphology Differs in Rotation and Obliquity Between Developmental Dysplasia of the Hip and Retroversion

BackgroundDevelopmental dysplasia of the hip (DDH) and acetabular retroversion represent distinct acetabular pathomorphologies. Both are associated with alterations in pelvic morphology. In cases where direct radiographic assessment of the acetabulum is difficult or impossible or in mixed cases of DDH and retroversion, additional indirect pelvimetric parameters would help identify the major underlying structural abnormality.Questions/PurposesWe asked: How does DDH and retroversion differ with respect to rotation and coronal obliquity as measured by the pelvic width index, anterior inferior iliac spine (AIIS) sign, ilioischial angle, and obturator index? And what is the predictive value of each variable in detecting acetabular retroversion?MethodsWe reviewed AP pelvis radiographs for 51 dysplastic and 51 retroverted hips. Dysplasia was diagnosed based on a lateral center-edge angle of less than 20° and an acetabular index of greater than 14°. Retroversion was diagnosed based on a lateral center-edge angle of greater than 25° and concomitant presence of the crossover/ischial spine/posterior wall signs. We calculated sensitivity, specificity, and area under the receiver operating characteristic (ROC) curve for each variable used to diagnose acetabular retroversion.ResultsWe found a lower pelvic width index, higher prevalence of the AIIS sign, higher ilioischial angle, and lower obturator index in acetabular retroversion. The entire innominate bone is internally rotated in DDH and externally rotated in retroversion. The areas under the ROC curve were 0.969 (pelvic width index), 0.776 (AIIS sign), 0.971 (ilioischial angle), and 0.925 (obturator index).ConclusionsPelvic morphology is associated with acetabular pathomorphology. Our measurements, except the AIIS sign, are indirect indicators of acetabular retroversion. The data suggest they can be used when the acetabular rim is not clearly visible and retroversion is not obvious.Level of EvidenceLevel III, diagnostic study. See Guidelines for Authors for a complete description of levels of evidence.

Real time, confocal imaging of Ca2+ waves in arterially perfused rat hearts

OBJECTIVE The aim of this study was to characterize the spatio-temporal dynamics of slow Ca(2+) waves (SCWs) with cellular resolution in the arterially-perfused rat heart. METHODS Wister rat hearts were Langendorff-perfused with Tyrode solution containing bovine-albumine and Dextran. The heart was loaded with the Ca(2+) sensitive dye Fluo-3 AM. Intracellular fluorescence changes reflecting changes in [Ca(2+)](i) were recorded from subepicardial tissue layers using a slit hole confocal microscope with an image intensified video camera system at image rates of up to 50/s. RESULTS SCWs appeared spontaneously during cardiac rest or after trains of electrical stimuli. They were initiated preferentially in the center third of the cell and propagated to the cell borders, suggesting a relation between the cell nucleus and wave initiation. They were suppressed by Ca(2+) transients and their probability of occurrence increased with the Ca(2+) resting level. Propagation velocity within myocytes (40 to 180 microm/s) decreased with the resting Ca(2+) level. Intercellular propagation was mostly confined to two or three cells and occurred bi-directionally. Intercellular unidirectional conduction block and facilitation of SCWs was occasionally observed. On average 10 to 20% of cells showed non-synchronized simultaneous SCWs within a given area in the myocardium. CONCLUSIONS SCWs occurring at increased levels of [Ca(2+)](i) in normoxic or ischemic conditions are mostly confined to two or three cells in the ventricular myocardium. Spatio-temporal summation of changes in membrane potential caused by individual SCWs may underlie the generation of triggered electrical ectopic impulses.

Surgical hip dislocation for osteochondral transplantation as a salvage procedure for a femoral head impaction fracture.

Obturator anterior hip dislocation is very rare. Poor results are described in patients with additional large transchondral fractures and treatment of these injuries remains challenging. Appropriate treatment recommendations are missing in the literature. This case report introduces surgical hip dislocation for osteochondral autograft transplantation with graft harvest from the nonweightbearing area of the head-neck junction as a salvage procedure in a large femoral head defect. We report the treatment and outcome of a 48-year-old man who sustained an anterior dislocation of the left hip after a motorcycle accident. After initial closed reduction in the emergency room, imaging analysis revealed a large osteochondral defect of the femoral head within the weightbearing area (10 × 20 mm, depth: 5 mm). The hip was exposed with a surgical hip dislocation using a trochanteric osteotomy. An osteochondral autograft was harvested from a nonweightbearing area of the femoral head and transferred into the defect. The patient was prospectively examined clinically and radiologically. Two years postoperatively, the patient was free of pain and complaints. The function of the injured hip was comparable to that of the contralateral, healthy hip and showed satisfying radiologic results. Surgical hip dislocation with a trochanteric flip osteotomy is a simple, one-step technique that allows full inspection of the hip to treat osteochondral femoral defects by osteochondral transplantation. The presented technique, used as a salvage procedure in a large femoral head defect, yielded good clinical and satisfying radiologic outcomes at the midterm.

In vitro temperature evaluation during cement augmentation of proximal humerus plate screw tips

BACKGROUND The treatment of proximal humerus fractures in patients with poor bone quality remains a challenge in trauma surgery. Augmentation with polymethylmethacrylate (PMMA) cement is a possible method to strengthen the implant anchorage in osteoporotic bone and to avoid loss of reduction and reduce the cut-out risk. The polymerisation of PMMA during cement setting leads, however, to an exothermic reaction and the development of supraphysiological temperatures may harm the bone and cartilage. This study addresses the issue of heat development during augmentation of subchondrally placed proximal humerus plate screws with PMMA and the possible risk of bone and cartilage necrosis and apoptosis. METHODS Seven fresh frozen humeri from geriatric female donors were instrumented with the proximal humerus interlocking system (PHILOS) plate and placed in a 37°C water bath. Thereafter, four proximal perforated screws were augmented with 0.5 ml PMMA each. During augmentation, the temperatures in the subchondral bone and on the articular surface were recorded with K-type thermocouples. The measured temperatures were compared to threshold values for necrosis and apoptosis of bone and cartilage reported in the literature. RESULTS The heat development was highest around the augmented tips of the perforated screws and diminished with growing distance from the cement cloud. The highest temperature recorded in the subchondral bone reached 43.5°C and the longest exposure time above 42°C was 86s. The highest temperature measured on the articular surface amounted to 38.6°C and the longest exposure time above 38°C was 5 min and 32s. CONCLUSION The study shows that augmentation of the proximal screws of the PHILOS plate with PMMA leads to a locally limited development of supraphysiological temperatures in the cement cloud and closely around it. The critical threshold values for necrosis and apoptosis of cartilage and subchondral bone reported in the literature, however, are not reached. In order to avoid cement extravasation, special care should be taken in detecting perforations or intra-articular cracks in the humeral head.

The Acetabular Wall Index for Assessing Anteroposterior Femoral Head Coverage in Symptomatic Patients

BackgroundUnderstanding acetabular pathomorphology is necessary to correctly treat patients with hip complaints. Existing radiographic parameters classify acetabular coverage as deficient, normal, or excessive but fail to quantify contributions of anterior and posterior wall coverage. A simple, reproducible, and valid measurement of anterior and posterior wall coverage in patients with hip pain would be a clinically useful tool.Questions/PurposesWe (1) introduce the anterior wall index (AWI) and posterior wall index (PWI), (2) report the intra- and interobserver reliability of these measurements, and (3) validate these measurements against an established computer model.MethodsWe retrospectively reviewed 87 hips (63 patients) with symptomatic hip disease. A validated computer model was used to determine total anterior and posterior acetabular coverage (TAC and TPC) on an AP pelvis radiograph. Two independent observers measured the AWI and PWI on each film, and the intraclass correlation coefficient (ICC) was calculated. Pearson correlation was used to determine the strength of linear dependence between our measurements and the computer model.ResultsIntra- and interobserver ICCs were 0.94 and 0.99 for the AWI and 0.81 and 0.97 for the PWI. For validation against the computer model, Pearson r values were 0.837 (AWI versus TAC) and 0.895 (PWI versus TPC). Mean AWI and PWI were 0.28 and 0.81 for dysplastic hips, 0.41 and 0.91 for normal hips, 0.61 and 1.15 for hips with a deep acetabulum.ConclusionsOur data suggest these measures will be helpful in evaluating anterior and posterior coverage before and after surgery but need to be evaluated in asymptomatic individuals without hip abnormalities to establish normal ranges.Level of EvidenceLevel III, diagnostic study. See Instructions for Authors for a complete description of levels of evidence.

Functional recovery following primary ACL repair with dynamic intraligamentary stabilization.

BACKGROUND Recently, a new technique, dynamic intraligamentary stabilization (DIS) was introduced for the acute repair of ACL ruptures. The purpose of this study was to report the functional recovery for patients undergoing acute anterior cruciate ligament (ACL) repair alongside DIS. METHODS Forty five patients sustaining acute ACL rupture and treated with DIS repair were retrospectively evaluated. Limb symmetry index of the hop test as well as knee function by means of range of motion, knee swelling, pain and maximum strength were evaluated. Following completion of the rehabilitation program, the difference in anterior-posterior translation (Δ-AP Translation), IKDC, Tegner score (TAS) was additionally analyzed. RESULTS Forty five (13 females, 32 males) patients were included in the study. Mean age was 26years (range 18 to 54years). Median time to successfully complete hop test was 22.0weeks (range 11 to 32weeks) postoperatively. Median limb symmetry index 91.6%±8.3%. Median delta anterior-posterior translation compared to the healthy side was plus 0.0mm±1.6mm. Median IKDC was 89.5±6.5. Mean Tegner score (TAS) at 12months of follow-up was seven (range four to nine). Three patients suffered a rerupture during the first 12 postoperative months. CONCLUSIONS DIS technique with proper rehabilitation following acute ACL rupture provides successful functional recovery and low rerupture rate at one-year follow-up.

Anterior approaches to the acetabulum

Since the 1960s the ilioinguinal approach by Letournel with the three anatomic windows has been successfully established for the treatment of acetabular fractures involving predominantly the anterior column. The previous standard approach, the iliofemoral approach by Smith-Petersen, is still used for the therapy of anterior wall or isolated femoral head fractures. The increase in acetabular fractures in the elderly with lateral compression fractures after lateral falls, characterized by medial displacement of the quadrilateral plate and superomedial dome impaction, led to the use of the intrapelvic modified Stoppa approach with or without the first window of the ilioinguinal approach in the 1990s. To combine the advantages of the second and third windows of the ilioinguinal approach and the medial view of the modified Stoppa approach the Berne research group recently introduced the pararectus approach in acetabular surgery, which can be used as a less invasive acetabular surgical (LIAS) technique especially in the elderly.ZusammenfassungSeit den 1960er Jahren hat sich zur Versorgung von Acetabulumfrakturen mit der Hauptdislokation im vorderen Pfeiler der ilioinguinale Zugang nach Letournel mit den drei anatomischen Fenstern bewährt. Der frühere Standardzugang, der iliofemorale Zugang nach Smith-Petersen, hat seine Bedeutung noch bei Vorderwandfrakturen oder isolierten Femurkopffrakturen. Durch den Anstieg von Acetabulumfrakturen im Alter mit lateralen Kompressionsfrakturen nach seitlichem Sturz, gekennzeichnet durch die mediale Dislokation der quadrilateralen Fläche und die superomediale Domimpression, hat sich in den 1990er Jahren der intrapelvine modifizierte Stoppa-Zugang mit oder ohne Eröffnung des 1. Fensters des ilioinguinalen Zugangs etabliert. Um die Vorteile der 2. und 3. Fenster des ilioinguinalen und die mediale Sicht beim modifizierten Stoppa-Zugang zu kombinieren, hat die Berner Arbeitsgruppe kürzlich den Pararectus-Zugang für die Acetabulumchirurgie eingeführt, der als weniger invasiver Zugang mit kleinen Inzisionen speziell bei alten Patienten einsetzbar ist.AbstractSince the 1960s the ilioinguinal approach by Letournel with the three anatomic windows has been successfully established for the treatment of acetabular fractures involving predominantly the anterior column. The previous standard approach, the iliofemoral approach by Smith-Petersen, is still used for the therapy of anterior wall or isolated femoral head fractures. The increase in acetabular fractures in the elderly with lateral compression fractures after lateral falls, characterized by medial displacement of the quadrilateral plate and superomedial dome impaction, led to the use of the intrapelvic modified Stoppa approach with or without the first window of the ilioinguinal approach in the 1990s. To combine the advantages of the second and third windows of the ilioinguinal approach and the medial view of the modified Stoppa approach the Berne research group recently introduced the pararectus approach in acetabular surgery, which can be used as a less invasive acetabular surgical (LIAS) technique especially in the elderly.

What Are the Risk Factors for Revision Surgery After Hip Arthroscopy for Femoroacetabular Impingement at 7-year Followup?

BackgroundIn recent years, surgical treatment of symptomatic femoroacetabular impingement (FAI) has been increasingly performed using arthroscopy. Bony pathomorphologies and damage to the labrum as well as cartilage defects can be addressed with comparable results to open surgery with overall less surgery-related complications. Despite the increasing importance of hip arthroscopy, however, reports on midterm clinical and radiographic outcomes and comparison to open surgical hip dislocation are scarce.Questions/purposes(1) What are the clinical and radiographic outcomes at a mean 7-year followup; (2) what is the cumulative 7-year survivorship, using the endpoints of THA, progression of osteoarthritis according to Tönnis, or poor clinical outcome with a Merle d’Aubigné score of less than 15 points, of hips with symptomatic FAI treated arthroscopically; and (3) what factors were associated with revision surgery?MethodsBetween 2003 and 2008 we performed a total of 62 arthroscopic procedures (60 patients) for FAI. For the same indication, we also performed 571 surgical hip dislocations during that time. Standardized treatment was femoral offset correction, acetabular rim trimming, or both and treatment of labral or chondral defects. An arthroscopic approach was generally used if the pathomorphology was located in the anterosuperior quadrant of the hip and was gradually used for more complex cases. We excluded 10 hips (10 patients) in which the standardized treatment was not achieved and no offset correction or acetabular rim trimming was performed. Of the remaining 52 hips (50 patients), 39 hips underwent isolated femoral offset correction, four hips isolated acetabular rim trimming, and nine hips both procedures. At a mean followup of 7 years (range, 5–11 years), the Merle d’Aubigné clinical score was obtained and plain radiographs were examined (Tönnis grade, heterotopic ossification, lateral center-edge [LCE] angle, acetabular index [AI], extrusion index, alpha angle, and pistol grip deformity). Cumulative survivorship was calculated according to Kaplan-Meier using conversion to THA, progression of osteoarthritis (one or more Tönnis grades), or poor clinical outcome (Merle d’Aubigné score < 15 points) as endpoints. Cox regression analysis was used to identify univariate factors associated with revision surgery.ResultsAt last followup we detected a significant but possibly not clinically relevant increase in Merle d’Aubigné scores from preoperative levels to latest followup (14 ± 1 versus 16 ± 2, mean difference 2 points with a 95% confidence interval [95% CI] −3 to 7, p < 0.001). Six hips showed progression of osteoarthritis. Cumulative survivorship (hips free from conversion to THA, progression of osteoarthritis, or poor clinical outcome) of hips treated with hip arthroscopy for FAI at a mean followup of 7 years was 81% (95% CI, 68%–95%). Two patients (two hips, 4%) underwent THA at 7 and 9 years, respectively. An increased preoperative acetabular coverage (LCE angle, AI), increased offset in the superior portion of the femoral neck (pistol grip deformity), and a remaining pistol grip deformity postoperatively were associated with revision surgery. Any treatment of the labrum did not influence the outcome. Factors associated with failure could not be identified.ConclusionsIn this series of patients with arthroscopic treatment of symptomatic FAI, hip arthroscopy resulted in an intact hip without progression of osteoarthritis and with a Merle d’Aubigné score of ≥ 15 points in 81% of patients at 7-year followup. Increased acetabular coverage and femoral pistol grip deformity were risk factors for revision surgery.Level of EvidenceLevel IV, therapeutic study.