Age and "general health"-beside fracture classification-affect the therapeutic decision for geriatric pelvic ring fractures: a German pelvic injury register study.

PURPOSE: Pelvic ring fractures in the elderly gain increasing importance. Nonetheless, data on factors influencing treatment decision in relation to fracture classification, age, and the resulting treatment are still rare. METHODS: Prospectively collected data of the German Pelvic Injury Registry from patients aged over 65 years with a pelvic ring fracture were evaluated retrospectively. Acetabular fractures, as well as type A1 and A3 fractures, were excluded. The variables age, injury pattern, type of treatment, the reason for conservative treatment, and Orthopaedic Trauma Association (OTA)/Tile classification were analyzed. Furthermore, the fracture distribution was examined after dividing patients into six age groups. RESULTS: A total of 1814 patients with a mean age of 80.7 ± 7.6 years, predominantly female (79.0%), were available for evaluation. The majority of patients suffered from isolated pelvic ring fractures (70.1%) and 8.2% were severely injured (ISS > 16). The most common fracture types were type A2 (35.4%), type B2 (38.0%), and type C1 (7.3%). Especially pelvic ring fractures of type A2 (96.9%) and type B2 (83.0%) were treated conservatively (overall 76.9%). Fracture instability according to the OTA/Tile classification increased the probability for an operative treatment (generalized odds ratio [OR] 6.90 [5.62; 8.52]). In contrary, increasing age independent of the fracture pattern decreased this probability (OR 0.47 [0.41-0.53]). With increasing fracture instability, general health conditions were up to 50% of the reasons for conservative treatment. CONCLUSION: The results of the present study underline the importance of the factors age and general health besides fracture classification for therapeutic decision-making in the treatment of pelvic ring fractures in the elderly.

Human osteochondritis dissecans fragment-derived chondrocyte characteristics ex vivo, after monolayer expansion-induced de-differentiation, and after re-differentiation in alginate bead culture.

BACKGROUND: Autologous chondrocyte implantation (ACI) is a therapy for articular cartilage and osteochondral lesions that relies on notch- or trochlea-derived primary chondrocytes. An alternative cell source for ACI could be osteochondritis dissecans (OCD) fragment-derived chondrocytes. Assessing the potential of these cells, we investigated their characteristics ex vivo and after monolayer expansion, as monolayer expansion is an integral step of ACI. However, as monolayer expansion can induce de-differentiation, we asked whether monolayer-induced de-differentiation can be reverted through successive alginate bead culture. METHODS: Chondrocytes were isolated from the OCD fragments of 15 patient knees with ICRS grades 3-4 lesions for ex vivo analyses, primary alginate bead culture, monolayer expansion, and alginate bead culture following monolayer expansion for attempting re-differentiation. We determined yield, viability, and the mRNA expression of aggrecan and type I, II, and X collagen. RESULTS: OCD fragment-derived chondrocyte isolation yielded high numbers of viable cells with a low type I:II collagen expression ratio (< 1) and a relatively high aggrecan and type II and X collagen mRNA expression, indicating chondrogenic and hypertrophic characteristics. As expected, monolayer expansion induced de-differentiation. Alginate bead culture of monolayer-expanded cells significantly improved the expression profile of all genes investigated, being most successful in decreasing the hypertrophy marker type X collagen to 1.5% of its ex vivo value. However, the chondrogenic phenotype was not fully restored, as the collagen type I:II expression ratio decreased significantly but remained > 1. CONCLUSION: OCD fragment derived human chondrocytes may hold not yet utilized clinical potential for cartilage repair.

Influence of tibialis posterior muscle activation on foot anatomy under axial loading: A biomechanical CT human cadaveric study.

BACKGROUND: Collapse of the medial longitudinal arch and subluxation of the subtalar joint are common occurrences in adult flatfoot deformity. Controversy exists about the role of the tibialis posterior (TP) tendon as first and/or essential lesion. Subtle changes in the foot configuration can occur under weight bearing. PURPOSE: This human cadaveric study is designed to investigate the effect that isolated actuation of the TP tendon has on the medial longitudinal arch and the hindfoot configuration under simulated weight bearing. METHODS: A radiolucent frame was developed to apply axial loading on cadaveric lower legs during computer tomography (CT) examinations. Eight pairs of fresh-frozen specimens were imaged in neutral position under foot-flat loading (75N) and under single-leg stance weight bearing (700N) without and with addition of 150N pulling force on the TP tendon. Measurements of subtalar joint subluxation, forefoot arch angle and talo-first metatarsal angle were conducted on each set of CT scans. RESULTS: Subtalar subluxation, talo-first metatarsal angle and talo-navicular coverage angle significantly increased under single-leg stance weight bearing, whereas forefoot arch angle significantly decreased. Actuation of the TP tendon under weight bearing did not restore the forefoot arch angle or correct subtalar subluxation and talo-metatarsal angle. CONCLUSION: Significant effect that weight bearing has on the medial longitudinal arch and the subtalar joint configuration is demonstrated in an ex-vivo model. In absence of other medial column derangement, actuation of the TP tendon alone does not seem to reconstitute the integrity of the medial longitudinal arch or correct the hindfoot subluxation under weight bearing. CLINICAL RELEVANCE: The findings of this study together with the developed model for ex-vivo investigation provide a further insight in foot anatomy.

Transsacral Osseous Corridor Anatomy Is More Amenable To Screw Insertion In Males: A Biomorphometric Analysis of 280 Pelves.

BACKGROUND: Percutaneous iliosacral screw placement is the standard procedure for fixation of posterior pelvic ring lesions, although a transsacral screw path is being used more frequently in recent years owing to increased fracture-fixation strength and better ability to fix central and bilateral sacral fractures. However, biomorphometric data for the osseous corridors are limited. Because placement of these screws in a safe and effective manner is crucial to using transsacral screws, we sought to address precise sacral anatomy in more detail to look for anatomic variation in the general population. QUESTIONS/PURPOSES: We asked: (1) What proportion of healthy pelvis specimens have no transsacral corridor at the level of the S1 vertebra owing to sacral dysmorphism? (2) If there is no safe diameter for screw placement in the transsacral S1 corridor, is an increased and thus safe diameter of the transsacral S2 corridor expected? (3) Are there sex-specific differences in sacral anatomy and are these correlated with known anthropometric parameters? METHODS: CT scans of pelves of 280 healthy patients acquired exclusively for medical indications such as polytrauma (20%), CT angiography (70%), and other reasons (10%), were segmented manually. Using an advanced CT-based image analysis system, the mean shape of all segmented pelves was generated and functioned as a template. On this template, the cylindric transsacral osseous corridor at the level of the S1 and S2 vertebrae was determined manually. Each pelvis then was registered to the template using a free-form registration algorithm to measure the maximum screw corridor diameters on each specimen semiautomatically. RESULTS: Thirty of 280 pelves (11%) had no transsacral S1 corridor owing to sacral dysmorphism. The average of maximum cylindrical diameters of the S1 corridor for the remaining 250 pelves was 12.8 mm (95% CI, 12.1-13.5 mm). A transverse corridor for S2 was found in 279 of 280 pelves, with an average of maximum cylindrical diameter of 11.6 mm (95% CI, 11.3-11.9 mm). Decreasing transsacral S1 corridor diameters are correlated with increasing transsacral S2 corridor diameters (R value for females, -0.260, p < 0.01; for males, -0.311, p < 0.001). Female specimens were more likely to have sacral dysmorphism (defined as a pelvis without a transsacral osseous corridor at the level of the S1 vertebra) than were male specimens (females, 16%; males, 7%; p < 0.003). Furthermore female pelves had smaller-corridor diameters than did male pelves (females versus males for S1: 11.7 mm [95% CI, 10.6-12.8 mm] versus 13.5 mm [95% CI, 12.6-14.4 mm], p < 0.01; and for S2: 10.6 mm [95% CI, 10.1-11.1 mm] versus 12.2 mm [95% CI, 11.8-12.6 mm ], p < 0.0001). CONCLUSIONS: Narrow corridors and highly individual, sex-dependent variance of morphologic features of the sacrum make transsacral implant placement technically demanding. Individual preoperative axial-slice CT scan analyses and orthogonal coronal and sagittal reformations are recommended to determine the prevalence of sufficient-sized osseous corridors on both levels for safe screw placements, especially in female patients, owing to their smaller corridor diameters and higher rate of sacral dysmorphism.

Analysis of sacro-iliac joint screw fixation: does quality of reduction and screw orientation influence joint stability? A biomechanical study.

INTRODUCTION: Treatment of posterior pelvic ring injuries is frequently associated with pain or/and high mortality rates. Percutaneous sacro-iliac (SI) screw fixation has proved to be one of the methods of choice, providing minimal operative time, blood loss and wound-related morbidity. However, fixation failures due to secondary fracture dislocation or screw backing out have been reported. There is a little knowledge regarding the impact of varying screw orientation and quality of reduction on the fixation strength. PURPOSE: The purpose of the present study was biomechanical investigation of joint stability after SI screw fixation and its dependence on quality of reduction and screw orientation. METHODS: Thirty-two artificial hemi-pelvices were assigned to four study groups and simulated SI dislocations were fixed with two SI screws in oblique or transverse screw orientation and anatomical or non-anatomical reduction in group A (oblique/anatomical), B (transverse/anatomical), C (oblique/non-anatomical) and D (transverse/non-anatomical). Mechanical testing was performed under progressively increasing cyclic axial loading until fixation failure. SI joint movements were captured via optical motion tracking. Fixation performance was statistically evaluated at a level of significance p = 0.05. RESULTS: The highest cycles to failure were observed in group A (14038 ± 1057), followed by B (13909 ± 1217), D (6936 ± 1654) and C (6706 ± 1295). Groups A and B revealed significantly longer endurance than C and D (p ≤ 0.01). CONCLUSIONS: Different screw orientations in the presented model do not influence substantially SI joint stability. However, anatomical reduction is not only mandatory to restore a malalignment, but also to increase the SI screw fixation strength and prevent fixation failures.

Sex-specific differences of the infraacetabular corridor: a biomorphometric CT-based analysis on a database of 523 pelves.

BACKGROUND: An infraacetabular screw path facilitates the closure of a periacetabular fixation frame to increase the plate fixation strength in acetabular fractures up to 50%. Knowledge of the variance in corridor sizes and axes has substantial surgical relevance for safe screw placement. QUESTIONS/PURPOSES: (1) What proportion of healthy pelvis specimens have an infraacetabular corridor that is 5 mm or larger in diameter? (2) Does a universal corridor axis and specific screw entry point exist? (3) Are there sex-specific differences in the infraacetabular corridor size or axis and are these correlated with anthropometric parameters like age, body weight and height, or the acetabular diameter? METHODS: A template pelvis with a mean shape from 523 segmented pelvis specimens was generated using a CT-based advanced image analyzing system. Each individual pelvis was registered to the template using a free-form registration algorithm. Feasible surface regions for the entry and exit points of the infraacetabular corridor were marked on the template and automatically mapped to the individual samples to perform a measurement of the maximum sizes and axes of the infraacetabular corridor on each specimen. A minimum corridor diameter of at least 5 mm was defined as a cutoff for placing a 3.5-mm cortical screw in clinical settings. RESULTS: In 484 of 523 pelves (93%), an infraacetabular corridor with a diameter of at least 5 mm was found. Using the mean axis angulations (54.8° [95% confidence interval {CI}, 0.6] from anterocranial to posterocaudal in relation to the anterior pelvic plane and 1.5° [95% CI, 0.4] from anteromedial to posterolateral in relation to the sagittal midline plane), a sufficient osseous corridor was present in 64% of pelves. Allowing adjustment of the three-dimensional axis by another 5° included an additional 25% of pelves. All corridor parameters were different between females and males (corridor diameter, 6.9 [95% CI, 0.2] versus 7.7 [95% CI, 0.2] mm; p<0.001; corridor length, 96.2 [95% CI, 0.7] versus 106.4 [95% CI, 0.6] mm; p<0.001; anterior pelvic plane angle, 54.0° [95% CI, 0.9] versus 55.3° [95% CI, 0.8]; p<0.01; sagittal midline plane angle, 4.3° [95% CI, 0.6] versus -0.3° [95% CI, 0.5]; p<0.001). CONCLUSION: This study provided reference values for placement of a 3.5-mm cortical screw in the infraacetabular osseous corridor in 90% of female and 94% of male pelves. Based on the sex-related differences in corridor axes, the mean screw trajectory is approximately parallel to the sagittal midline plane in males but has to be tilted from medial to lateral in females. Considering the narrow corridor diameters, we suggest an individual preoperative CT scan analysis for fine adjustments in each patient.

Reconstruction of the coracoacromial ligament during a modified Latarjet procedure: a case series.

BACKGROUND: The coracoacromial ligament (CAL) is an important restraint to superior shoulder translation. CAL release with the Latarjet procedure leads to increased superior humeral translation. Therefore, a surgical technique was developed to reconstruct the CAL during a modified Latarjet procedure. METHODS: Between May 2010 and July 2011, six patients (five were male, one was female; age 23-41 years) with chronic post-traumatic anterior shoulder instability were treated surgically with a modified congruent-arc Latarjet procedure (modLAT) with additional reconstruction of the CAL using a newly developed procedure, the pectoralis minor fascia flap (PMFF). Clinical follow-up was performed for up to 36 months, and patients were evaluated using a Rowe score. RESULTS: All six patients experienced chronic, post-traumatic anterior shoulder instability and had experienced multiple re-dislocations after initial treatment. The preoperative assessment showed a defect of the anterior glenoid in three cases, and the mean Rowe score was 16.67 (5-25). Open modLAT with PMFF resulted in a stable shoulder function with no re-dislocations. The Rowe score increased from 77.5 (65-90) at 12 weeks to 95 (90-100) at 12 months and plateaued thereafter. Operative duration was 95 min (78-112 min), and there were no intra- or postoperative complications. All patients returned to their preoperative sports activity, three at the same level. CONCLUSION: The PMFF is a safe technique for reconstruction of the CAL during a modLAT procedure. Patients had improved shoulder function and no re-dislocations after the surgery.

First Tarsometatarsal Arthrodesis: An Anatomic Evaluation of Dorsomedial Versus Plantar Plating.

Fusion of the first tarsometatarsal joint is a widely used procedure for the correction of hallux valgus deformity. Although dorsomedial H-shaped plating systems are being increasingly used, fusion can also be achieved by plantar plating. The goal of the present study was to compare these 2 operative techniques based on the anatomic considerations and show the potential pitfalls of both procedures. Six pairs of deep-frozen human lower legs were used in the present cadaveric study. In a randomized manner, either dorsomedial arthrodesis or plantar plating through a medial incision was performed. With regard to arterial injury, the plantar technique resulted in fewer lesions (plantar, 4 injuries [66.7%] to the terminal branches of the first digital branch of the medial plantar artery; dorsomedial, 3 injuries [50%] to the main trunks of the plantar metatarsal arteries and the first dorsal metatarsal artery). With respect to injury to the veins, the plantar procedure affected significantly fewer high-caliber subcutaneous trunk veins. The nerves coursing through the operative field, such as the saphenous and superficial fibular nerves, were compromised more often by the dorsal approach. Neither the plantar plating nor the dorsomedial plating technique was associated with injury to the insertion of the tibialis anterior muscle. Both studied techniques are safe, well-established procedures. Arthrodesis with plantar plating, however, offers additional advantages and is a reliable tool in the foot and ankle surgeon's repertoire.

Lateral soft-tissue release through a medial incision: Anatomic comparison of two techniques.

BACKGROUND: The distal soft tissue procedure is an integral part of hallux valgus surgery, providing soft tissue balance and alignment restoration of the first metatarsophalangeal joint. Various approaches have been established to this end. For techniques that do not include a separate dorsal incision, lateral release may be achieved via a transarticular approach or via a medial incision and a dorsal flap over the first metatarsal. Compared to the double-incision technique, these techniques are not only cosmetically superior and thus meet the demands of most surgeons and patients. MATERIAL AND METHODS: Using six pairs of frozen cadaveric feet, lateral release was performed using one of the above techniques in a randomized manner with pair comparison. The specimens were then dissected and the completeness of the release as well as any damage to anatomic structures was documented. RESULTS: The transarticular technique enabled complete release of the metatarsal-sesamoid suspensory ligament (MSL) and the transverse and oblique head of the adductor hallucis muscle in five of six specimens. The comparative technique enabled the same in only two of six cases for the adductor hallucis muscle and in four cases for the MSL. The transarticular approach achieved complete release of the lateral joint capsule in three of six specimens, whereas the dorsal approach achieved no release in any specimen. Neither of the methods caused any macroscopic injury to the surfaces of the first metatarsophalangeal joint. The examined arteries, veins, and nerves remained intact in all specimens treated with the transarticular approach, but dorsal release resulted in one documented injury to the first dorsal metatarsal artery and its concomitant veins. CONCLUSIONS: Compared to release by dissection superficially to the extensor tendons, transarticular release provides a more complete lateral release and less injuries to neurovascular bundles. Further anatomic and clinical studies are needed, however, before conclusive recommendations can be made.

Percutaneous navigated screw fixation of glenoid fractures.

BACKGROUND: Open or percutaneous arthroscopic-based procedures are reported to fix unstable or displaced intra-articular glenoid fractures. Approach related morbidity has to be considered for open procedures, and arthroscopic-based procedures are demanding. Therefore an alternative percutaneous navigated approach is described. TECHNICAL PROCEDURE: In an experimental setting an operative workflow was simulated to evaluate the best position of the patient on the operation table, the operating room set up and the fixation technique for the dynamic reference base of the navigation system. Based on two clinical cases, screw fixation of glenoid fractures via a posterior percutaneous approach is described, using a 2D-fluoroscopic based navigation system. Compared to the common approaches, the advantages and disadvantages of this procedure are discussed. CONCLUSION: The described technique of percutaneous navigated screw fixation of glenoid fractures is an alternative minimal invasive procedure. A reduction of approach related morbidity and more rapid return to function could be expected. The intraoperative results and postoperative functional outcome of both cases are promising.

Modified Lapidus arthrodesis with plantar plate and compression screw for treatment of hallux valgus with hypermobility of the first ray: a preliminary report.

BACKGROUND: TMT-1 arthrodesis is an established method in hallux valgus surgery, but it is technically demanding and typically calls for a period of postoperative immobilization. METHODS: In this cohort study, initial experience with a plantar plate is described. 58 patients (59 arthrodesis) were included. RESULTS: The mean duration of protected full weight bearing was 7 weeks. 94.12% patients were satisfied with the results, bony union was achieved in 98.31%. The Foot Function Index improved by 33 to a mean of 8 (p<.001). The postoperative Mayo Clinic Forefoot Score was excellent in 47.04 and good in 47.04%. The mean hallux valgus angle improved by 24.4-13.2° (p<.001). The mean first intermetatarsal angle improved by 11.2-5.2° (p<.001). CONCLUSION: Initial experience with this form of fixation appears to provide suitable stability, allow early-protected weight bearing, with an acceptable level of complications.

A computed tomography based survey study investigating the agreement of the therapeutic strategy for fragility fractures of the pelvis.

Treatment recommendations for fragility fractures of the pelvis (FFP) have been provided along with the good reliable FFP classification but they are not proven in large studies and recent reports challenge these recommendations. Thus, we aimed to determine the usefulness of the FFP classification determining the treatment strategy and favored procedures in six level 1 trauma centers. Sixty cases of FFP were evaluated by six experienced pelvic surgeons, six inexperienced surgeons in training, and one surgeon trained by the originator of the FFP classification during three repeating sessions using computed tomography scans with multiplanar reconstruction. The intra-rater reliability and inter-rater reliability for therapeutic decisions (non-operative treatment vs. operative treatment) were moderate, with Fleiss kappa coefficients of 0.54 (95% confidence interval [CI] 0.44-0.62) and 0.42 (95% CI 0.34-0.49). We found a therapeutic disagreement predominantly for FFP II related to a preferred operative therapy for FFP II. Operative treated cases were generally treated with an anterior-posterior fixation. Despite the consensus on an anterior-posterior fixation, the chosen procedures are highly variable and most plausible based on the surgeon's preference.

Fluoro-Free navigated retrograde drilling of osteochondral lesions.

PURPOSE: Retrograde drilling of osteochondral lesions (OCLs) is a recommended, but demanding operative approach for revascularization of lesions in stage 1-3 according to Berndt and Harty after failed conservative treatment. The gold standard of intraoperative driller guidance is fluoroscopic control. Limitations are a 2D visualization of a 3D procedure and sometimes limited view of the OCL in fluoroscopy, leading to increased radiation exposure. A new image-free navigation procedure was evaluated for practicability and precision in first clinical applications. METHODS: In a period of 7 months, retrograde drillings were performed in eight patients (3x femoral condyle, 5x talus) using the new Fluoro-Free navigation procedure without rigidly fixed reference bases. RESULTS: In total, 29 retrograde drillings were performed without any technical problem. The overall mean operating time was 82.1 ± 29.3 min (34.6 ± 6.4 min for the standard arthroscopy and 11.2 ± 1.2 min per drill). Twenty-seven of 29 drillings hit the target with a 100% first-pass accuracy. Two complications during drilling (one navigation specific and one navigation independent) were observed. CONCLUSION: The paper describes the promising first clinical applications of a new Fluoro-Free navigation procedure for the retrograde drilling of OCLs determined by arthroscopy. The benefit of that navigated drillings with a high rate of first-pass accuracy and no need for radiation exposure in contrast to standard techniques is highlighted.

Short-term outcome of retrograde tibiotalocalcaneal arthrodesis with a curved intramedullary nail.

BACKGROUND: The aim of this study was to investigate the potential clinical benefit of tibiotalocalcaneal arthrodesis (TTCA) with an intramedullary nail with a valgus curve, two compression options, and angle-stable locking. MATERIAL AND METHODS: Patients who had undergone TTCA at two tertiary hospitals were eligible. Patients who had undergone TTCA before the beginning of the study were evaluated retrospectively, then all following patients were examined prospectively. There were 59 TTCAs; 55 patients were available for analysis. Twenty-eight were evaluated retrospectively, 27 prospectively. Main Outcome Measures were an SF-36, Mazur-, and AOFAS ankle-hindfoot rating scores and radiographic examination. RESULTS: Bony union was obtained in 53 patients. Fifty-one patients were satisfied with the outcome. Fifty-one patients had marked subjective improvement in mobility. The mean AOFAS score of the 55 patients at the latest followup was 66.8 (range, 38 to 86). The mean Mazzur score was 68.0 (range, 30 to 83). In the prospective group, the scores were significantly improved: AOFAS score by an average of 39.6 points (p<0.001); Mazur score by an average of 43 points (p<0.001); SF-36 physical component summary score (p<0.001) and mental component summary score also improved (p<0.048). Radiology showed good hindfoot alignment. The complication rate was 25%. CONCLUSION: Compared with the literature, the data obtained in this study show a good outcome and a high rate of bony union, with comparable complication rates. Patient satisfaction was good. However, the patients still had limitations. The clinical benefit of the nail used was confirmed.

Plantar versus dorsomedial locked plating for Lapidus arthrodesis: a biomechanical comparison.

BACKGROUND: Lapidus arthrodesis with a plate and a compression screw is an established procedure in hallux valgus surgery. The present study was performed to investigate the potential benefit of a compression screw combined with a plantarly applied angle-stable, anatomically precontoured plate or a dorsomedially applied angle-stable plate. METHODS: In six pairs of human cadaver specimens, one specimen each was randomized to receive a dorsomedial H-shaped plate, while the other received a plantar plate. Bone mineral density was measured with peripheral quantitative computed tomography. The specimens were loaded quasi-statically, followed by cyclic loading. Finally, they were loaded to failure. In the static tests, stiffness and range of motion (ROM) data were obtained. In the cyclic tests, the constructs' displacement was studied. In the load-to-failure test, stiffness and maximum load to failure were measured. RESULTS: The two groups did not differ significantly with regard to BMD (p = 0.25). Any significant differences observed were in favor of the plantar constructs, which had greater initial stiffness (p = 0.028) and final stiffness (p = 0.042), a smaller ROM (p = 0.028), and a greater load to failure (p = 0.043). There was no significant difference regarding displacement (p = 0.14). CONCLUSION: In the static tests, the plantar angle-stable plate construct was superior to the dorsomedial angle-stable plate construct. CLINICAL RELEVANCE: Plantar plating appears to offer biomechanical benefit. Clinical studies will be required to show whether this translates into earlier resumption of weightbearing and into lower rates of nonunion.

Arthroscopic controlled reduction of femoral condyle fractures using a retrograde navigated approach.

Isolated depression fractures of the femoral condyle are rare, but severe injuries due the destroyed congruency of the articular surface in the weight-bearing region of the joint. In most cases, an arthrotomy with fragment reduction and internal fixation by screws buttress or plates is performed. Disadvantages of this procedure are the approach-related complications. Furthermore, an implant removal is necessary, if a secondary osteoarthrosis develops. We present a female patient with a hyperflexion trauma of her right knee, resulting in an isolated depression fracture of the medial femoral condyle. To avoid arthrotomy-related morbidity, the impressed fragment was retrograde addressed using navigated guidance and reduced indirectly under arthroscopic control. Via the retrograde intraosseous tunnel a biodegradable screw was used as a buttress against the fragment to prevent a re-dislocation. The fracture healed without any complications and the patient re-administered her sports activities at 10 weeks follow-up. This procedure enables an accurate reduction and stable fixation of joint depression fragments via a minimal invasive approach.

Navigation of vertebro-pelvic fixations based on CT-fluoro matching.

Different navigation procedures (based on 2D-, 3D-fluoroscopy or CT modalities) with their respective limitations are established in orthopedic surgery. The hypothesis is that intraoperative matching of different modalities (fluoro and CT) increases the precision of navigated screw placement and reduces the fluoroscopy time. Vertical unstable pelvic ring fractures of 12 patients were treated with vertebro-pelvic fixations (6 in the standard technique and 6 using the fluoro-CT navigation). An optimal osseous corridor could be determined by the navigation procedure increasing the overall precision of screw placement (no misplacement in the second group as compared to one misplaced pedicle screw in the standard group). The achieved screw lengths were [(mean ± SE) 78 ± 5 vs. 53 ± 4 mm, p < 0.001). Less invasive open approaches and a reduction of fluoroscopy time (time per screw in seconds: 121 vs. 62 s) were observed. CT-fluoro-matched navigation improves the intraoperative visualization of osseous structures and increases the precision of screw placement with less radiation exposure.

2D-fluoroscopic navigated percutaneous screw fixation of pelvic ring injuries--a case series.

BACKGROUND: Screw fixation of pelvic ring fractures is a common, but demanding procedure and navigation techniques were introduced to increase the precision of screw placement. The purpose of this case series was the evaluation of screw misplacement rate and functional outcome of percutaneous screw fixation of pelvic ring disruptions using a 2D navigation system. METHODS: Between August 2004 and December 2007, 44 of 442 patients with pelvic injuries were included for closed reduction and percutaneous screw fixation of disrupted pelvic ring lesions using an optoelectronic 2D-fluoroscopic based navigation system. Operating and fluoroscopy time were measured, as well as peri- and postoperative complications documented. Screw position was assessed by postoperative CT scans. Quality of live was evaluated by SF 36-questionnaire in 40 of 44 patients at mean follow up 15.5 +/- 1.2 month. RESULTS: 56 iliosacral- and 29 ramus pubic-screws were inserted (mean operation time per screw 62 +/- 4 minutes, mean fluoroscopy time per screw 123 +/- 12 seconds). In post-operative CT-scans the screw position was assessed and graded as follows: I. secure positioning, completely in the cancellous bone (80%); II. secure positioning, but contacting cortical bone structures (14%); III. malplaced positioning, penetrating the cortical bone (6%). The malplacements predominantly occurred in bilateral overlapping screw fixation. No wound infection or iatrogenic neurovascular damage were observed. Four re-operations were performed, two of them due to implant-misplacement and two of them due to implant-failure. CONCLUSION: 2D-fluoroscopic navigation is a safe tool providing high accuracy of percutaneous screw placement for pelvic ring fractures, but in cases of a bilateral iliosacral screw fixation an increased risk for screw misplacement was observed. If additional ramus pubic screw fixations are performed, the retrograde inserted screws have to pass the iliopubic eminence to prevent an axial screw loosening.

Navigated percutaneous screw fixation of a periprosthetic acetabular fracture.

Periprosthetic fractures are severe complications of total hip arthroplasty with increasing incidence. Most fractures are localized around the femoral component of prosthesis, whereas periacetabular fractures are rare and their management is difficult. In most cases, an operative procedure with revision and exchange of the acetabular cup is necessary. The approaches are demanding and an increased risk of complications is reported. We present the case of a female patient with a cementless total hip arthroplasty due to severe arthritis, suffering of an infratectal transverse periprosthetic fracture. After an initial conservative treatment attempt, we performed a minimally invasive screw fixation using navigated 2-dimensional fluoroscopic guidance. In this report, the literature for treatment recommendations is reviewed and the chosen navigation technique discussed.

Arthroscopic-controlled navigation for retrograde drilling of osteochondral lesions of the talus.

BACKGROUND: Retrograde drilling of symptomatic osteochondral lesions (OCL) is usually controlled by fluoroscopy. Due to the limited visualization of the OCLs in the acquired images and the narrow access to the talar dome, this approach can be demanding. Several navigation procedures have been reported (2D- or 3D- fluoroscopy or intraoperative CT-based) to increase the accuracy and reduce the radiation exposure. We developed a new arthroscopic-controlled navigation procedure which is free of radiation exposure and free of a reference base rigidly fixed to the bone. We hypothesized that this procedure (Fluoro-Free) is at least as precise as the standard 2D-Fluoro navigation (2D-Fluoro). Furthermore, our first clinical experiences are described and discussed. MATERIAL AND METHODS: Sixteen drillings per group (standard 2D-Fluoro vs. Fluoro-Free) were performed in artificial sawbones. Times for the different steps of each drilling procedure were recorded and the precision evaluated by measuring the deviation and depth of drilling. RESULTS: The accuracy of the Fluoro-Free navigation was as precise as the standard 2D-Fluoro based navigation (axis deviation of drill tip to the target point: 1.07 ± 0.11 versus 1.14 ± 0.15 mm). Due to the simplified workflow without radiation exposure and fixation of a reference base, the Fluoro-Free procedure was significantly faster (mean procedure time per drilling: 23.7 ± 11.6 versus 165 ± 9 seconds) and easy to use. Its clinical usefulness was demonstrated during three retrograde drillings of a talar OCL in a 16-year-old patient. CONCLUSION: The Fluoro-Free navigation procedure is a simplified approach for retrograde drilling of OCL in the talus under arthroscopic control without radiation exposure and without the need for fixation of a dynamic reference base to the bone.