V. Smekal

The medial periosteal hinge, a key structure in fractures of the proximal humerus: A BIOMECHANICAL CADAVER STUDY OF ITS MECHANICAL PROPERTIES

The medial periosteal hinge plays a key role in fractures of the head of the humerus, offering mechanical support during and after reduction and maintaining perfusion of the head by the vessels in the posteromedial periosteum. We have investigated the biomechanical properties of the medial periosteum in fractures of the proximal humerus using a standard model in 20 fresh-frozen cadaver specimens comparable in age, gender and bone mineral density. After creating the fracture, we displaced the humeral head medial or lateral to the shaft with controlled force until complete disruption of the posteromedial periosteum was recorded. As the quality of periosteum might be affected by age and bone quality, the results were correlated with the age and the local bone mineral density of the specimens measured with quantitative CT. Periosteal rupture started at a mean displacement of 2.96 mm (SD 2.92) with a mean load of 100.9 N (SD 47.1). The mean maximum load of 111.4 N (SD 42.5) was reached at a mean displacement of 4.9 mm (SD 4.2). The periosteum was completely ruptured at a mean displacement of 34.4 mm (SD 11.1). There was no significant difference in the mean distance to complete rupture for medial (mean 35.8 mm (SD 13.8)) or lateral (mean 33.0 mm (SD 8.2)) displacement (p = 0.589). The mean bone mineral density was 0.111 g/cm(3) (SD 0.035). A statistically significant but low correlation between bone mineral density and the maximum load uptake (r = 0.475, p = 0.034) was observed. This study showed that the posteromedial hinge is a mechanical structure capable of providing support for percutaneous reduction and stabilisation of a fracture by ligamentotaxis. Periosteal rupture started at a mean of about 3 mm and was completed by a mean displacement of just under 35 mm. The microvascular situation of the rupturing periosteum cannot be investigated with the current model.

Elastic stable intramedullary nailing is best for mid-shaft clavicular fractures without comminution: Results in 60 patients

INTRODUCTION Elastic stable intramedullary nailing (ESIN) of displaced mid-shaft clavicular fractures is a minimally invasive technique which was reported to be an easy procedure with low complication rates, good cosmetic and functional results, restoration of clavicular length and fast return to daily activities. Recent studies, however, also report on higher complication rates and specific problems with the use of this technique. This prospective study compares ESIN with non-operative treatment of displaced mid-shaft clavicular fractures. METHODS Between December 2003 and August 2007, 120 patients volunteered to participate. Of these, 112 patients completed the study (60 in the operative and 52 in the non-operative group). Patients in the non-operative group were treated with a simple shoulder sling. In the operative group, intramedullary stabilisation was performed within 3 days of the trauma. Clavicular shortening was determined after trauma and after osseous consolidation on thorax posteroanterior radiographs as the proportional length difference between the left and right side with the uninjured side serving as a control for clavicular length (100%). Radiographic union was assessed every 4 weeks on 20 degrees cephalad anteroposterior and posteroanterior radiographs of the clavicle. Constant shoulder scores and DASH scores (DASH, disabilities of the arm, shoulder and hand) were assessed at final follow-up after 2 years. RESULTS ESIN led to faster osseous healing and better restoration of clavicular length in simple fractures. We were not able to restore clavicular length in comminuted fractures using ESIN. Functional outcome at a mean follow-up of 24 months (range: 22-27 months) was better in the operative group. Delayed union and non-union accounted for the majority of complications in the non-operative group. In the operative group, telescoping was the main complication, which occurred in complex fractures with severe post-traumatic shortening only. CONCLUSION We recommend ESIN for all simple displaced mid-shaft clavicular fractures in order to minimise the rate of delayed union, non-union and symptomatic mal-union. We also recommend ESIN in comminuted fractures with moderate (< or = 7%) post-traumatic shortening, as they will heal with moderate shortening. In comminuted fractures with severe shortening, however, we recommend plate osteosynthesis in order to provide for stability, clavicular length and endosteal blood supply.

Revision anterior cruciate ligament reconstruction: an update

With the rising number of anterior cruciate ligament (ACL) reconstructions performed, revision ACL reconstruction is increasingly common nowadays. A broad variety of primary and revision ACL reconstruction techniques have been described in the literature. Recurrent instability after primary ACL surgery is often due to non-anatomical ACL graft reconstruction and altered biomechanics. Anatomical reconstruction must be the primary goal of this challenging revision procedure. Recently, revision ACL reconstruction has been described using double bundle hamstring graft. Successful revision ACL reconstruction requires an exact understanding of the causes of failure and technical or diagnostic errors. The purpose of this article is to review the causes of failure, preoperative evaluation, graft selection and types of fixation, tunnel placement, various types of surgical techniques and clinical outcome of revision ACL reconstruction.

The influence of distal locking on the need for fibular plating in intramedullary nailing of distal metaphyseal tibiofibular fractures

Using human cadaver specimens, we investigated the role of supplementary fibular plating in the treatment of distal tibial fractures using an intramedullary nail. Fibular plating is thought to improve stability in these situations, but has been reported to have increased soft-tissue complications and to impair union of the fracture. We proposed that multidirectional locking screws provide adequate stability, making additional fibular plating unnecessary. A distal tibiofibular osteotomy model performed on matched fresh-frozen lower limb specimens was stabilised with reamed nails using conventional biplanar distal locking (CDL) or multidirectional distal locking (MDL) options with and without fibular plating. Rotational stiffness was assessed under a constant axial force of 150 N and a superimposed torque of ± 5 Nm. Total movement, and neutral zone and fracture gap movement were analysed. In the CDL group, fibular plating improved stiffness at the tibial fracture site, albeit to a small degree (p = 0.013). In the MDL group additional fibular plating did not increase the stiffness. The MDL nail without fibular plating was significantly more stable than the CDL nail with an additional fibular plate (p = 0.008). These findings suggest that additional fibular plating does not improve stability if a multidirectional distal locking intramedullary nail is used, and is therefore unnecessary if not needed to aid reduction.

Marknagelung distaler Unterschenkelfrakturen am Beispiel des ExpertTM Tibianagels

OBJECTIVE Restoration of axis, length, and rotation of the lower leg. Sufficient primary stability of the osteosynthesis for functional aftercare and to maintain joint mobility. Good bony healing in closed and open fractures. INDICATIONS Closed and open fractures of the tibia and complete lower leg fractures distal to the isthmus (AO 42), extraarticular fractures of the distal tibia (AO 43 A1/A2/A3), segmental fractures of the tibia with a fracture in the distal tibia, and certain intraarticular fractures of the distal tibia without impression of the joint line with the use of additional implants (AO 43 C1) CONTRAINDICATIONS Patient in reduced general condition (e.g., bed ridden), flexion of the knee of less than 90°, patients with knee arthroplasty of the affected leg, infection in the area of the nails insertion, infection of the tibial cavity, complex articular fractures of the proximal or distal tibia with joint depression. SURGICAL TECHNIQUE Closed reduction of the fracture preferably on a fracture table or using a distractor or an external fixation frame. If necessary, use pointed reduction clamps or sterile drapery. In some cases, additional implants like percutaneous small fragment screws, poller screws or k-wires are helpful. Open reduction is rarely necessary and must be avoided. Opening of the proximal tibia in line with the medullary canal. Canulated insertion of the Expert(TM) tibia nail (ETN; Synthes GmbH, Oberdorf, Switzerland) with reaming of the medullary canal. Control of axis, length, and rotation. Distal interlocking with the radiolucent drill and proximal interlocking with the targeting device. POSTOPERATIVE MANAGEMENT Immediate mobilization of ankle and knee joint. Mobilization with 20 kg weight-bearing with crutches. X-ray control 6 weeks postoperatively and increased weight-bearing depending on the fracture status. In cases with simple fractures, good bony contact, or transverse fracture pattern, full weight-bearing at the end of week 6 is targeted. RESULTS Between July 2004 and May 2005, 180 patients were included in a multicenter study. The follow-up rate was 81% after 1 year. Of these, 91 fractures (50.6%) were located in the distal third of the tibia. In this segment, the rate of delayed union was 10.6%. Malalignment of > 5° was observed in 5.4%. A secondary malalignment after initial good reduction was detected in only 1.1% of all cases. The implant-specific risk for screw breakage was 3.2%. One patient sustained a deep infection. If additional fibula plating was performed an 8-fold higher risk for delayed bone healing was observed (95%CI: 2.9-21.2, p< 0.001). If the fracture of the fibula was at the same height as on the tibia, the risk for delayed healing was even 14-fold (95% CI: 3.4-62.5, p< 0.001). Biomechanically plating of the fibula does not increase stability in suprasyndesmal distal tibia-fibular fractures treated with an intramedullary nail. Using the ETN with its optimized locking options, fibula plating is not recommended, thus, avoiding soft tissue problems and potentially delayed bone healing.

Pressure distribution in carpometacarpal joint, due to step-off in operatively treated Bennett's fractures

INTRODUCTION The purpose of the current study was to investigate the effects of residual articular incongruity after Bennetts fracture on load distribution of the joint surface. Our aim was to investigate whether a residual joint step and the altered load distribution led to negative clinical outcomes or symptomatic degenerative osteoarthritis of the trapeziometacarpal joint. PATIENTS AND METHODS Twenty-four patients were available for long-term follow-up examination and were contacted by phone, and they returned for follow-up examination. Computed tomography (CT) scans of both carpometacarpal (CMC) joints were performed. CT scans were taken in the sagittal plane of the forearms with a slice thickness of 0.625 mm for three-dimensional reconstruction. The CMC joints were analysed due to a residual step in the joint. Only patients with a residual step-off were included in this study. To determine the areas of maximum density in the joint, CT-osteoabsorptiometry was performed. RESULTS Ten patients had the maximum loading area radial and two patients central. The second major position of mineralization was detected central in four patients, volar-ulnar in two patients, radial in one patient, dorso-radial in one patient, volar in one patient and volar-radial in two patients. CONCLUSION Finally, no higher loading in the area of the beak fragment could be found. The Wagner technique, even if it results in a persistent 1-2-mm intra-articular step-off of the beak fragment, is still the favourable method for the treatment of Bennetts luxation fractures.

Screw oversizing for anterior cruciate ligament graft fixation in primary and enlarged tibial tunnels: A biomechanical study in a porcine model

BACKGROUND Ideal diameter for tibial interference screw fixation of the anterior cruciate ligament (ACL) graft remains controversial. Tibial graft fixation with screws matching the tunnel diameter vs. one-millimetre oversized screws were compared. METHODS In 32 cadaveric porcine tibiae, bovine extensor tendons with a diameter of eight millimetres were fixed in (I) a primary ACL reconstruction scenario with eight-millimetre tibial tunnels (pACL), with eight-millimetre (pACL-8) vs. nine-millimetre (pACL-9) screws, and (II) a revision ACL reconstruction scenario with enlarged tunnels of 10 mm (rACL), with 10-mm (rACL-10) vs. 11-mm (rACL-11) screws. Specimens underwent cyclic loading with low and high load magnitudes followed by a load-to-failure test. Graft slippage and ultimate failure load were recorded. RESULTS In comparison with matched-sized screws (pACL-8), fixation with oversized screws (pACL-9) showed with significantly increased graft slippage during cyclic loading at higher load magnitudes (1.19 ± 0.23 vs. 1.98 ± 0.67 mm; P = 0.007). There were no significant differences between the two screw sizes in the revision scenario (rACL-10 vs. rACL-11; P = 0.38). Graft fixation in the revision scenario resulted in significantly increased graft slippage in comparison with fixation in primary tunnels at higher loads (pACL vs. rACL; P = 0.004). Pull-out strengths were comparable for both scenarios and all screw sizes (P > 0.316). CONCLUSIONS Matched-sized interference screws provided better ACL graft fixation in comparison with an oversized screw diameter. In revision cases, the fixation strength of interference screws in enlarged tunnels was inferior to the fixation strength in primary tunnels.

Tunnel widening after ACL reconstruction with aperture screw fixation or all-inside reconstruction with suspensory cortical button fixation: Volumetric measurements on CT and MRI scans☆

BACKGROUND Tunnel widening after anterior cruciate ligament reconstruction (ACLR) is influenced by the surgical and fixation techniques used. Computed tomography (CT) is the most accurate image modality for assessing tunnel widening, but magnetic resonance imaging (MRI) might also be reliable for tunnel volume measurements. In the present study tunnel widening after ACLR using biodegradable interference screw fixation was compared with all-inside ACLR using button fixation, with tunnel volume changes being measured on CT and MRI scans. STUDY DESIGN Randomized controlled trial; Level of evidence, 2. METHODS Thirty-three patients were randomly assigned to hamstring ACLR using a biodegradable interference screw or all-inside cortical button fixation. CT and MRI scanning were done at the time of surgery and six months after. Tunnel volume changes were calculated and compared. RESULTS On CT, femoral tunnel volumes changed from the postoperative state (100%) to 119.8% with screw fixation and 143.2% with button fixation (P=0.023). The changes in tibial tunnel volumes were not significant (113.9% vs. 117.7%). The changes in bone tunnel volume measured on MRI were comparable with those on CT only for tunnels with interference screws. Tibial tunnels with button fixation were significantly underestimated on MRI scanning (P=0.018). CONCLUSIONS All-inside ACLR using cortical button fixation results in increased femoral tunnel widening in comparison with ACLR with biodegradable interference screw fixation. MRI represents a reliable imaging modality for future studies investigating tunnel widening with interference screw fixation.

Marknagelung distaler Unterschenkelfrakturen am Beispiel des ExpertTM

OBJECTIVE Restoration of axis, length, and rotation of the lower leg. Sufficient primary stability of the osteosynthesis for functional aftercare and to maintain joint mobility. Good bony healing in closed and open fractures. INDICATIONS Closed and open fractures of the tibia and complete lower leg fractures distal to the isthmus (AO 42), extraarticular fractures of the distal tibia (AO 43 A1/A2/A3), segmental fractures of the tibia with a fracture in the distal tibia, and certain intraarticular fractures of the distal tibia without impression of the joint line with the use of additional implants (AO 43 C1) CONTRAINDICATIONS Patient in reduced general condition (e.g., bed ridden), flexion of the knee of less than 90°, patients with knee arthroplasty of the affected leg, infection in the area of the nails insertion, infection of the tibial cavity, complex articular fractures of the proximal or distal tibia with joint depression. SURGICAL TECHNIQUE Closed reduction of the fracture preferably on a fracture table or using a distractor or an external fixation frame. If necessary, use pointed reduction clamps or sterile drapery. In some cases, additional implants like percutaneous small fragment screws, poller screws or k-wires are helpful. Open reduction is rarely necessary and must be avoided. Opening of the proximal tibia in line with the medullary canal. Canulated insertion of the Expert(TM) tibia nail (ETN; Synthes GmbH, Oberdorf, Switzerland) with reaming of the medullary canal. Control of axis, length, and rotation. Distal interlocking with the radiolucent drill and proximal interlocking with the targeting device. POSTOPERATIVE MANAGEMENT Immediate mobilization of ankle and knee joint. Mobilization with 20 kg weight-bearing with crutches. X-ray control 6 weeks postoperatively and increased weight-bearing depending on the fracture status. In cases with simple fractures, good bony contact, or transverse fracture pattern, full weight-bearing at the end of week 6 is targeted. RESULTS Between July 2004 and May 2005, 180 patients were included in a multicenter study. The follow-up rate was 81% after 1 year. Of these, 91 fractures (50.6%) were located in the distal third of the tibia. In this segment, the rate of delayed union was 10.6%. Malalignment of > 5° was observed in 5.4%. A secondary malalignment after initial good reduction was detected in only 1.1% of all cases. The implant-specific risk for screw breakage was 3.2%. One patient sustained a deep infection. If additional fibula plating was performed an 8-fold higher risk for delayed bone healing was observed (95%CI: 2.9-21.2, p< 0.001). If the fracture of the fibula was at the same height as on the tibia, the risk for delayed healing was even 14-fold (95% CI: 3.4-62.5, p< 0.001). Biomechanically plating of the fibula does not increase stability in suprasyndesmal distal tibia-fibular fractures treated with an intramedullary nail. Using the ETN with its optimized locking options, fibula plating is not recommended, thus, avoiding soft tissue problems and potentially delayed bone healing.

Marknagelung distaler Unterschenkelfrakturen am Beispiel des ExpertTM Tibianagels@@@Intramedullary nailing of the distal tibia illustrated with the ExpertTM tibia nail

OBJECTIVE Restoration of axis, length, and rotation of the lower leg. Sufficient primary stability of the osteosynthesis for functional aftercare and to maintain joint mobility. Good bony healing in closed and open fractures. INDICATIONS Closed and open fractures of the tibia and complete lower leg fractures distal to the isthmus (AO 42), extraarticular fractures of the distal tibia (AO 43 A1/A2/A3), segmental fractures of the tibia with a fracture in the distal tibia, and certain intraarticular fractures of the distal tibia without impression of the joint line with the use of additional implants (AO 43 C1) CONTRAINDICATIONS Patient in reduced general condition (e.g., bed ridden), flexion of the knee of less than 90°, patients with knee arthroplasty of the affected leg, infection in the area of the nails insertion, infection of the tibial cavity, complex articular fractures of the proximal or distal tibia with joint depression. SURGICAL TECHNIQUE Closed reduction of the fracture preferably on a fracture table or using a distractor or an external fixation frame. If necessary, use pointed reduction clamps or sterile drapery. In some cases, additional implants like percutaneous small fragment screws, poller screws or k-wires are helpful. Open reduction is rarely necessary and must be avoided. Opening of the proximal tibia in line with the medullary canal. Canulated insertion of the Expert(TM) tibia nail (ETN; Synthes GmbH, Oberdorf, Switzerland) with reaming of the medullary canal. Control of axis, length, and rotation. Distal interlocking with the radiolucent drill and proximal interlocking with the targeting device. POSTOPERATIVE MANAGEMENT Immediate mobilization of ankle and knee joint. Mobilization with 20 kg weight-bearing with crutches. X-ray control 6 weeks postoperatively and increased weight-bearing depending on the fracture status. In cases with simple fractures, good bony contact, or transverse fracture pattern, full weight-bearing at the end of week 6 is targeted. RESULTS Between July 2004 and May 2005, 180 patients were included in a multicenter study. The follow-up rate was 81% after 1 year. Of these, 91 fractures (50.6%) were located in the distal third of the tibia. In this segment, the rate of delayed union was 10.6%. Malalignment of > 5° was observed in 5.4%. A secondary malalignment after initial good reduction was detected in only 1.1% of all cases. The implant-specific risk for screw breakage was 3.2%. One patient sustained a deep infection. If additional fibula plating was performed an 8-fold higher risk for delayed bone healing was observed (95%CI: 2.9-21.2, p< 0.001). If the fracture of the fibula was at the same height as on the tibia, the risk for delayed healing was even 14-fold (95% CI: 3.4-62.5, p< 0.001). Biomechanically plating of the fibula does not increase stability in suprasyndesmal distal tibia-fibular fractures treated with an intramedullary nail. Using the ETN with its optimized locking options, fibula plating is not recommended, thus, avoiding soft tissue problems and potentially delayed bone healing.