Andreas H. Ruecker

Comparison of open versus percutaneous pedicle screw insertion in a sheep model

Minimally invasive surgery has become more and more important for the treatment of traumatic spine fractures. Besides, some clinical studies, objective data regarding the possible lower damage to the surrounding tissue of the spine is still missing. Here we report a sheep model where we compared a percutaneous versus an open approach for dorsal instrumentation with pedicle screws to the spine. Twelve skeletally mature sheep underwent bilateral pedicle screw fixation at the L4–L6 level. Forty-eight pedicle screws were bilaterally inserted into the pedicles and connected with rods using either an open dorsal standard or a percutaneous approach. Operation time, blood flow, compartment pressure, radiation time, loss of blood, laboratory findings and EMG were evaluated to objectify possible advantages for the percutaneous operation technique. Loss of blood and the distribution of CK-MM as a marker for muscle damage were significantly lower in the percutaneous group. However, radiation time was significantly longer in the percutaneous group. Other parameters like compartment pressure, blood flow and also measurement of the EMG at different time points did not reveal significant differences. Based on the results we found in the present study, percutaneous screw insertion can bring moderate advantages but it should be noted that essential functional deficits to the muscle could not be detected.

Present and Future Therapies of Articular Cartilage Defects

AbstractBackground: Until today, no universally successful therapy to treat substantial articular cartilage defects has been available. Numerous therapeutic approaches can only improve clinical symptoms of joint lesions, but cannot stimulate the regenerative and reactive capacity of the biological tissue in the defect, and, thus, cannot restore an articular surface capable of functional load bearing. Some other therapeutic options promised impressing results at the beginning, but did not withstand the process of a closer investigation. Even after laborious, invasive and expensive therapies, patients still complain about pain, joint effusions, restricted movement, or articular blockage. Established and Novel Therapies: The aim of all therapeutic procedures to treat patients with damaged articular cartilage is to reconstruct the integrity of the articular cartilage surface in order to enable them to live an unrestricted painless professional and private life. This article gives an overview of the clinically established procedures, their indications and the present long-term results, as well as a crucial look on the limitations of each approach. Novel therapies, which integrate molecular biology techniques and tissue engineering into transplantation surgery, are introduced and analyzed in terms of their capability and future potential.

Malpositioning of the lag screws by 1- or 2-screw nailing systems for pertrochanteric femoral fractures: a biomechanical comparison of gamma 3 and intertan.

OBJECTIVES: The aim of this investigation was to perform a biomechanical comparison between one- and two-screw-systems used for the treatment of intertrochanteric fractures for centralized and decentralized placement of femoral-neck-screws in terms of failure loads, stiffness, survival rates, tip apex distance (TAD) and failure mode. METHODS: As fracture model, an AO 31A2.3 fracture was used. 12 pairs of human cadaver femora were tested. Femoral-neck-screws were implanted in the femoral head in center/center, posterior/central, and anterior/superior position in axial/frontal plane. A single-screw-system (Gamma 3 Locking Nail, Stryker) and a two-screw-system (Trigen-Intertan, Smith & Nephew) were used. To simulate the load in-situ, a cyclic load was carried for 10,000 cycles in a material-testing-machine. If no cyclic failure occurred, femora were loaded until failure. The systems were compared according stiffness, survivability through 10k cycles, TAD and load to failure. RESULTS: None of the tested bones failed at center/center location, in the decentralized positions 3 GammaNail and 2 Intertan specimens failed during cyclic testing. The two-screw-system resisted higher forces in all positions (Gamma: 5370N±1924, Intertan: 7650N±2043, p=0.014). CONCLUSIONS: Based on these data it is clear that both nail systems showed a higher biomechanical stability with a lower TAD. The two specimens that failed with the Intertan in the cyclic tests had a TAD ≥ 49mm. The cut-out failures that we detected during cyclic testing in the Gamma system had a TAD of ≥ 30mm. Thus it is clear that the TAD affects failure independent of the implant used. With a less than ideal lag screw placement however, the Intertan system with two integrated screws, was able to withstand higher loads in our study.

Accuracy Analysis of a Novel Electromagnetic Navigation Procedure Versus a Standard Fluoroscopic Method for Retrograde Drilling of Osteochondritis Dissecans Lesions of the Knee

Background: Retrograde drilling for osteochondritis dissecans (OCD) remains a challenging operation. Purpose: A novel radiation-free electromagnetic navigation system (ENS)–based method was developed and its feasibility and accuracy for retrograde drilling procedures evaluated and compared with the standard freehand fluoroscopic method in an experimental setting. Study Design: Controlled laboratory study. Methods: A controlled laboratory study with 16 standard freehand fluoroscopically and 16 electromagnetically guided retrograde drilling procedures was performed on 8 cadaveric human knees. Four artificial cartilage lesions (2 on each condyle) were set per knee. Drilling accuracy was determined by final distance from the tip of the drill bit to the tip of the probe hook (D1) and distance between the tip of the drill and the marked lesion on the cartilage surface (D2). Intraoperative fluoroscopy exposure times were documented, as were directional readjustments or complete restarts. All procedures were timed using a stopwatch. Results: Successful retrograde drilling was accomplished in all 16 cases using the novel ENS-based method and in 11 cases using the standard fluoroscopic technique. The overall mean time for the fluoroscopy-guided procedures was 10 minutes 55 seconds ± 3 minutes 19 seconds and for the ENS method was 5 minutes 34 seconds ± 38 seconds, providing a mean time benefit of 5 minutes 35 seconds (P < .001). Mean D1 was 3.8 ± 1.6 mm for the standard and 2.3 ± 0.6 mm using the ENS technique (P = .021), and mean D2 was 2.5 ± 1.3 mm for the standard and 0.9 ± 0.7 mm for the ENS-based method (P < .001). Conclusion: Compared with the standard fluoroscopic technique, the novel ENS-based method used in this study showed superior accuracy, required less time, and utilized no radiation. Clinical Relevance: The novel method improves a standard operating procedure in terms of accuracy, operation time for the retrograde drilling procedure, and radiation exposure.

3D fluoroscopic navigated reaming of the glenoid for total shoulder arthroplasty (TSA).

Survival rates for total shoulder arthroplasty are critically dependent on the correct placement of the glenoid component. Especially in osteoarthritis, pathological version of the glenoid occurs frequently and has to be corrected surgically by eccentric reaming of the glenoid brim. The aim of our study was to evaluate whether eccentric reaming of the glenoid can be achieved more accurately by a novel computer assisted technique. Procedures were conducted on 10 paired human cadaveric specimens presenting glenoids with neutral version. To identify the correction potential of the navigated technique compared to the standard procedure, asymmetric reaming of the glenoid to create a version of −10° was defined as the target. In the navigated group, asymmetric reaming was guided by a 3D fluoroscopic technique. Postoperative 3D scans revealed greater accuracy for the eccentric reaming procedure in the navigated group compared to the freehand group, resulting in glenoid version of −9.8 ± 3.8° and −5.1 ± 4.1°, respectively (p < 0.05). Furthermore, deviation from preoperative planning was significantly reduced in the navigated group. These data indicate that our navigated procedure offers an excellent tool for supporting glenoid replacement in TSA.

Retrograde Drilling of Talar Osteochondritis Dissecans Lesions: A Feasibility and Accuracy Analysis of a Novel Electromagnetic Navigation Method Versus a Standard Fluoroscopic Method

PURPOSE A novel method using an electromagnetic navigation system (ENS) was developed, and its feasibility and accuracy for retrograde drilling procedures were evaluated and compared with the standard freehand fluoroscopic method in an experimental setting. METHODS A controlled laboratory study of 16 standard freehand fluoroscopically guided and 16 electromagnetically navigated retrograde drilling procedures was performed on 4 cadaveric human ankle joints. Four artificial cartilage lesions were consecutively set, 2 on the medial and 2 on the lateral talar dome. Drilling accuracy was measured in terms of the distance from the final position of the drill bit to the tip of the probe hook and the distance between the tip of the drill bit and the center of the cartilage lesion on the articular cartilage surface. Intraoperative fluoroscopy exposure times were documented, as were readjustments of drilling directions or complete restarts. All procedures were timed with a stopwatch. RESULTS Successful retrograde drilling was accomplished in 12 cases with the standard fluoroscopy-guided technique and in all 16 ENS-guided procedures. The overall mean time for the fluoroscopy-guided procedures was 660.00 ± 239.87 seconds and the overall mean time for the ENS method was 308.06 ± 54.03 seconds, providing a mean time benefit of 420.13 seconds. The mean distance from the final position of the drill bit to the tip of the probe hook was 3.25 ± 1.29 mm for the standard method and 2.19 ± 0.54 mm for the ENS method, and the mean distance between the tip of the drill bit and the center of the cartilage lesion on the articular cartilage surface was 2.50 ± 0.97 mm for the standard method and 0.88 ± 0.81 mm for the ENS method. CONCLUSIONS Compared with the standard fluoroscopic technique, the ENS method used in this study showed higher accuracy and a shorter procedure time and required no X-ray radiation. CLINICAL RELEVANCE The novel method considerably improves on the standard operating procedure in terms of safety, operation time, and radiation exposure.

Management of traumatic spinopelvic dissociations: review of the literature

PurposeSpinopelvic dissociation is a rare high-energy injury pattern in adults associated with high morbidity and an increased rate of neurological deficits. The purpose of this article is the conception of fracture type-associated treatment recommendations.MethodsThis article is based on our own experience with spinopelvic dissociations and a review of the current literature.ResultsBilateral vertical plus an optional transverse fracture component configures spinopelvic dissociations as “U”- or “H”-shaped, with the result of a spinopelvic dissociation. “Y”-, “T”- or “II”-shaped fractures do not necessarily belong to this entity but can be subsumed to this entity in a wider sense. The surgical treatment of these injuries remains challenging. Initial haemodynamic stabilisation represents the main goal of primary care until definitive treatment can be performed. Anatomical reduction is demanding and even more complex in fracture areas with large comminution. Surgical treatment options depend on the fracture type, including transsacral screws, sacral banding and spinopelvic fixation, plus combinations of these procedures.ConclusionsSpinopelvic dissociations remain highly complex injuries. “U”- and “H”-shaped fractures usually require triangular fixation, whereas “II”-, “Y”- and “T”-shaped fractures might be sufficiently stabilised with transsacral screws.

Distal Tibial Fractures: Intramedullary Nailing

The tibia is an exposed bone with vulnerable soft tissue coverage and is therefore predisposed to local soft tissue problems and delayed bone healing. The objective in distal tibial fracture treatment is to achieve stable fixation patterns with a minimum of soft-tissue affection. Thus, the risk of soft tissue breakdown and bone healing complications is more likely related to open reduction and plating. Percutaneous, minimally invasive intramedullary nailing is a proven fixation mode for fracture stabilization in tibial shaft fractures. Anticipating the pitfalls, intramedullary nailing meets the requirements of the method of choice in distal tibial fracture fixation. In conclusion, intramedullary nailing of distal tibial fractures is a reliable method of fixation, possessing the advantages of closed reduction and symmetric fracture stabilization of an area with a delicate soft tissue situation, but prospective randomized trials are needed to compare modern intramedullary fracture fixation with modern plate fixation in distal tibial fractures.

Frakturen des distalen Radius

The most prevalent fractures managed by trauma surgeons are those involving the distal radius. The injury occurs in two peaks of prevalence: the first peak around the age of 10 years and the second peak around the age of 60 years. Distal radius fracture management requires sensitive diagnostics and classification. The objectives of treatment are the reconstruction of a pain-free unlimited durable functioning of the wrist and avoidance of typical fracture complications. Non-operative conservative management is generally employed for stable non-displaced fractures of the distal radius with the expectation of a good functional outcome. Unstable comminuted fractures with intra-articular and extra-articular fragment zones are initially set in a closed operation and finally by osteosynthesis. An armament of surgical implants is available for instable fractures requiring fixation. Palmar locked plate osteosynthesis has been established in recent years as the gold standard for operative management of distal radius fractures. Complex Working Group on Osteosynthesis (AO) classification type 3 fractures require extensive preoperative diagnostics to identify and treat typical associated injuries around the wrist.

Fractures of the distal radius

The most prevalent fractures managed by trauma surgeons are those involving the distal radius. The injury occurs in two peaks of prevalence: the first peak around the age of 10 years and the second peak around the age of 60 years. Distal radius fracture management requires sensitive diagnostics and classification. The objectives of treatment are the reconstruction of a pain-free unlimited durable functioning of the wrist and avoidance of typical fracture complications. Non-operative conservative management is generally employed for stable non-displaced fractures of the distal radius with the expectation of a good functional outcome. Unstable comminuted fractures with intra-articular and extra-articular fragment zones are initially set in a closed operation and finally by osteosynthesis. An armament of surgical implants is available for instable fractures requiring fixation. Palmar locked plate osteosynthesis has been established in recent years as the gold standard for operative management of distal radius fractures. Complex Working Group on Osteosynthesis (AO) classification type 3 fractures require extensive preoperative diagnostics to identify and treat typical associated injuries around the wrist.