Biomechanical analysis of bicondylar tibial plateau fixation: how does lateral locking plate fixation compare to dual plate fixation?

OBJECTIVES: This study is designed to test the comparative strength of lateral-only locked plating to medial and lateral nonlocked plating in a cadaveric model of a bicondylar proximal tibial plateau fracture. METHODS: Ten matched pairs of human cadaveric proximal tibia specimens were used for biomechanical testing. Cyclic loading using a materials testing device simulated initial range of motion and load bearing following surgical repair. Subsidence of the medial and the lateral condyles was measured following 10,000 cycles from 100N to 1,000N; the maximum load to failure on the medial condyle for both plate constructs was also measured. RESULTS: On the lateral side, dual plating (DP) allowed an average of 0.68 +/- 0.14 mm of subsidence, compared with 1.03 +/- 0.27 mm for the fixed-angle plate (FAP) (P = 0.077). On the medial side, DP allowed an average of 0.78 +/- 0.15 mm of subsidence, compared with 1.51 +/- 0.32 mm for the FAP (P = 0.045). No significant difference was found in the maximal load to medial condyle fixation failure between either plating construct (P = 0.204). CONCLUSIONS: The results of this study demonstrate that dual-plate fixation allows less subsidence in this bicondylar tibial plateau cadaveric model when compared to isolated locked lateral plates. This may raise concerns about the widespread use of isolated lateral locked plate constructs in bicondylar tibial plateau fractures.     

Treatment of Gustilo grade Ⅲ leg fractures by external fixation associated with limited internal fixation

Objective： To explore the clinical effects of external fixation associated with limited internal fixation on treatment of Gustilo grade Ⅲ leg fractures. Methods： From July 2006 to December 2008, 40 cases of Gustilo grade Ⅲ leg fractures were emergently treated in our unit with external fixation frames. Soft tissue injuries were grouped according to the Gustilo classification as ⅢA in 17 cases, ⅢB in 13 cases, and ⅢC in 10 cases. All the patients were debrided within 8 hours, and then fracture reposition was preformed to reestablish the leg alignment. Limited internal fixation with plates and screws were performed on all the Gustilo IliA cases and 10 Gustilo ⅢB cases at the first operation. But all the Gustilo ⅢC cases and 3 Gustilo ⅢB cases who had severe soft tissue injuries and bone loss only received Vacuum-sealing drainage （VSD）. Broad-spectrum antibiotics were regularly used and VSD must be especially maintained easy and smooth for one week or more after operation. Limited internal fixation and transplanted free skin flaps or adjacent musculocutaneous flaps were not used to close wounds until the conditions of the wounds had been improved. Results： The first operations were completed within 90-210 minutes （170 minutes on average）. The blood trans- fusions were from 400 ml to 1500 ml （those used for antishock preoperatively not included）. All the 40 patients in this study were followed up for 6-28 months, 20.5 months on average. The lower limb function was evaluated according to the comprehensive evaluation standards of leg function one year after operation and the results of 28 cases were excellent, 9 were good and 3 were poor. Conclusion： External fixation associated with limited internal fixation to treat Gustilo grade Ⅲ leg fractures can get satisfactory early clinical therapeutic effects.     

Comparison of the safety of three methods of lumbar transpedicular screw fixation

Objective: To choose a proper method of lumbar transpedicular screw fixation at different lumbar levels among the three methods (Roy-Camille's method, Magerl's method and Du's method) in the Chinese population. Methods: Three-dimensional ( 3-D ) images were reconstructed with image data of 42 adult lumbar segments that were scanned by Electron Beam CT. The three methods of lumbar pedicle screw fixation were simulated on the 3-D reconstructed images and the parameters of implanting pedicle screws were measured. Results : There was statistically significant difference at the distance from the entrance point to the pedicle axis between the three methods (P<0.001). The distances measured by Du's method were shortest from L1 to L4, and the distances measured by Magerl's method were shortest at L5 (P<0.05). There was no significant difference from L1 to L2 (P >0.05) but significant difference from L3 to L5 at inserting safe ranges of TSA (transverse section angle) was found between the three methods (P<0.05). From L3 to L4, the inserting safe ranges of TSA measured by Du's and Magerl's methods were significantly larger than that measured by Roy-Camille's method (P<0.05), but there was no significant difference between them (P > 0.05). At L5, the inserting safe ranges of TSA measured by Magerl's method were largest among the three methods (P <0.05). Conclusions: Among the three methods, Du's method is the best choice from L1 to L4 because its distance from the entrance point to the pedicle axis is shortest and the safe range of TSA is largest: Magerl's method can be used from L3 to LS and is the best choice at L5; Roy-Camille's method is applicable at L1 and L2.     

Efficacy of three methods of internal fixation on femoral neck fracture

From 1990 to 2000, we used Hansson pin, AOhollow-pulling screw, and bendable screw to treat150 cases of fresh femoral neck fracture and theresult was analysed to compare the efficacy of the threemethods of internal fixation.     

Pedicle screw fixation against burst fracture of thoracolumbar vertebrae

Objective： To analyze the application of vertebral pedicle screw fixation in the treatment of burst fracture of thoracolumbar vertebrae. Methods： A total of 48 cases （31 males and 17 females, aged from 18-72 years, mean： 41.3 years ） with thoracolumbar vertebrae burst fracture were treated by pedicle screw system since January 2004. According to the AO classification of thoracolumbar vertebrae fracture, there are 36 cases of Type A, 9 of Type B and 3 of Type C. Results： All patients were followed up for 6-25 months （average 12 months ）, no secondary nerve root injury, spinal cord injury, loosening or breakage of pedicle screw were observed. The nerve function of 29 patients with cauda eqnina nerve injury was restored to different degrees. The vertebral body height returned to normal level and posterior process angle was rectified after operation. Conclusions： The vertebral pedicle screw internal fixation was technologically applicable, which can efficiently reposition and stablize the bursting fractured vertabrae, indirectly decompress canalis spinalis, maintain spine stablity, scatter stress of screw system, reduce the risk of loosening or breakage of screw and loss of vertebral height, and prevent the formation of posterior convex after operation.     

CT-guided internal fixation of a hangman’s fracture

Most hangman’s fractures are treated conservatively. If surgery is indicated, an anterior approach using a C2/C3 graft and plate fusion is usually preferred. Another surgical method according to Judet is direct transpedicular osteosynthesis by the dorsal approach. This surgery is frequently rejected because of the high risk of spinal cord damage or vertebral artery tear. Direct transpedicular osteosynthesis of hangman’s fracture according to Judet is a “physiological operation” that does not cause fusion and creates anatomical conditions. This procedure enables appropriate reduction, compression of fragments and immediate stabilization of the C2 segment. A new aspect of Judet’s method of internal fixation of a hangman’s fracture is now proposed. Computed tomographic (CT) guidance is used to ensure safe and exact introduction of two screws from the posterior approach. This method of CT-guided internal fixation of hangman’s fracture allows, preoperatively, for an accurate assessment of the pattern and course of fracture line, selection of the anatomically safest screw path and determination of an appropriate screw length. The procedure also allows for accurate intraoperative control of instrument and implant placement, screw tightening, fracture reduction and anchoring of the screw tip in the contralateral cortex, using repeated CT scans. The procedure is performed in a CT unit under sterile conditions. This method was used in the treatment of eight male and two female patients aged 21–71 years. All treated patients were without neurological deficit. Follow-up ranged from 12 to 57 months (mean 33.3 months). No intraoperative or early or late postoperative complications were apparent. This new aspect of the surgical procedure ensures highly accurate screw placement and minimal risks, and fully achieves the “physiological” internal fixation. Received: 25 January 1999/Revised: 26 February 2000/Accepted: 23 March 2000     

Renal phosphate handling of premature infants of 23–25 weeks gestational age

Premature infants with low serum phosphate concentrations (<2 mmol/l) are at risk for osteopenia. Therefore, serum phosphate levels in premature infants should be kept above 2 mmol/l. Premature infants of 26-31 weeks gestational age (GA) have renal phosphate threshold concentrations (Tp/GFR) in the range of normal serum phosphate values (2 mmol/l). Therefore, these infants show significant urinary phosphate excretion only when serum phosphate levels are normal, and urinary phosphate excretion can be used to monitor phosphate supplementation. However, few data are available on extremely premature infants of 23-25 weeks GA. The objective of this study was to compare Tp/GFR levels in infants of 23-25 weeks GA to those in infants of 26-31 weeks GA. We retrospectively evaluated case notes of 12 infants of 23-25 weeks GA and compared them to 19 infants of 26-31 weeks GA. Tp/GFR was calculated from simultaneous measurements of urinary phosphate, urinary creatinine, serum phosphate, and serum creatinine. Tp/GFR values 3-5 weeks postnatally were lower in infants of 23-25 weeks GA (1.06+/-0.36 mmol/l, p<0.001) than in infants of 26-31 weeks GA (1.76+/-0.26 mmol/l). Near term (35-37 weeks postmenstrual age), there was no significant difference between Tp/GFR values in infants of 23-25 weeks GA (1.83+/-0.32 mmol/l) and in infants of 26-31 weeks GA (2.05+/-0.22 mmol/l). We conclude that at 3-5 weeks postnatally, infants of 23-25 weeks GA are at risk for low Tp/GFR values, leading to urinary phosphate excretion even in the presence of low serum phosphate levels. In these infants, serum phosphate levels should be monitored, and phosphate supplementation should be adjusted to keep serum phosphate levels above 2 mmol/l.     

Stability of Lisfranc injury fixation in Thiel Cadavers: Is routine fixation of the 1st and 3rd tarsometatarsal joint necessary?

BackgroundThere is debate as to whether a home run screw (medial cuneiform to 2nd metatarsal base) combined with k-wire fixation of the 4th & 5th tarsometatarsal joints is sufficient to stabilise Lisfranc injuries or if fixation of the 1st and 3rd tarsometatarsal joints is also required. Unlike the 2nd, 4th and 5th tarsometatarsal joints, stabilisation of the 1st and 3rd requires either intra-articular screw or an extra-articular plate which risk causing chondrolysis and/or osteoarthritis.The aims of this cadaveric study were to determine if routine fixation of the 1st and 3rd tarsometatarsal joints is necessary and to determine if a distal to proximal home run screw is adequate.MethodsUsing 8 Theil-embalmed specimens, measurements of tarsometatarsal joint dorsal displacement at each ray (1st–5th) and 1st–2nd metatarsal gaping were made during simulated weight bearing with sequential ligamentous injury and stabilisation to determine the contribution of anatomical structures and fixation to stability.ResultsAt baseline, mean dorsal tarsometatarsal joint displacement of the intact specimens during simulated weight bearing (mm) was: 1st: 0.14, 2nd: 0.1, 3rd:0, 4th: 0, 5th: 0.14. The 1st–2nd intermetatarsal gap was 0 mm. After transection of the Lisfranc ligament only, there was 1st–2nd intermetatarsal gaping (mean 4.5 mm), but no increased dorsal displacement. After additional transection of all the tarsometatarsal joint ligaments, dorsal displacement increased at all joints (1st: 4.5, 2nd: 5.1, 3rd: 3.6, 4th: 2, 5th: 1.3). Stabilisation with the home run screw and 4th and 5th ray k-wires virtually eliminated all displacement. Further transection of the inter-metatarsal ligaments increased mean dorsal displacement of the 3rd ray to 2.5 mm. K-wire fixation of the 3rd ray completely eliminated dorsal displacement.ConclusionsThe results of this cadaveric study suggest that stabilising the medial cuneiform to the 2nd metatarsal base combined with stabilisation of the 4th and 5th tarsometatarsal joints with K-wires will stabilise the 1st and 3rd tarsometatarsal joints if the inter-metatarsal ligaments are intact. Thus 3rd TMTJ stability should be checked after stabilising the 2nd and 4/5th. Provided the intermetatarsal ligaments (3rd–4th) are intact, the 3rd ray does not need to be routinely stabilised.     

Biomechanical analysis of fracture fixation with external fixator in vivo

Objective: To investigate the different ways of measuring the main axial strain during treatment with an external fixator and to find the suitable compression loaded by the external fixator at an early stage. Methods: Eighteen healthy big-ear rabbits were randomly divided into two groups according to different measuring methods: Group A and Group B. In Group A, a strain gauge was affixed to the external tibial cortex with 502 glue, and in Group B, a bone cement-coated strain gauge was installed on the internal tibial cortex. Groups A and B were divided into two subgroups A1, A2 and B1, B2, respectively, according to the pressure of half of and the same as the body weight. A Z-shaped left mid-shaft tibial osteotomy was performed and fixed by an external fixator. Results: The sealer curves of Group A changed dramatically during the early stage. The trendlines of the internal and external cortex went consistently after reaching the stable stage while the latter strain value was higher than the former. The time for Group B reaching the stable stage was short, but its absolute strain value was less than that of Group A. Before they were pressed to the stable stage, the declined speed of Subgroup A1 was more slowly than that of Subgroup A2 while the results of Subgroups Bl and B2 were same. Group A had an ascending trend after it declined while Group B didn' t have. After they reached the stable stage, both Subgroups Al and A2 had a declining trend while Subgroup A2 was more quickly than Subgroup A1, Subgroup Bl was kept at a definite level while Subgroup B2 fluctuated. Conclusions: The axial strain under external fixator can be measured by bone cement coated-strain gauge in vivo. The data may suggest that half of the body weight load was suitable for external fixator.     

Percutaneous fixation of scaphoïd fractures with arthroscopic assistance

We report the results of a series of 37 recent fractures of the scaphoid treated by percutaneous screwing under X-ray control with systematic realization of a wrist arthroscopy. In 22 cases the factures were undisplaced and we had 15 displaced fractures. In all the cases the wrist arthroscopy allows to check the quality of the reduction, the good positioning of the screws and the correct reduction of fragments. Union was obtained in all cases with an average of 62 days (range 45-80). The functional recovery of the operated wrists was good with an early return to work on average 21 days (between 0 days and 3 months). The systematic association of wrist arthroscopy to the percutaneous screwing secures the procedure which can be proposed to motived patients interested by a fast return to the active life. The quality and the stability of the reduction are controlled and avoid complications due to bad positioning of the material. The possibility of treating in the same time the associated intra carpal ligaments tears lesions is possible.     

Does transrenal fixation of aortic endografts impair renal function?

OBJECTIVES: Transrenal fixation (TFX) of aortic endografts is thought to increase the risk for renal infarction and impaired renal function. We studied the late effects of TFX on renal function and perfusion. METHODS: Of 189 patients with commercial aortic endografts, which we inserted between 1995 and 2002, we reviewed data for 130 patients (112 men, 18 women) with available creatinine (Cr) concentration and contrast enhanced computed tomography (CT) scans preoperatively and 1 to 97 months after the procedure. Of the 130 patients, 69 patients had TFX and 61 patients had infrarenal fixation (IFX). Both groups were physiologically comparable. Average age was 76 +/- 8 years for patients with TFX and 75 +/- 8 years for patients with IFX. Presence of renal infarct or renal artery occlusion was determined by nephrograms on serial contrast-enhanced CT scans. RESULTS: Mean follow-up was 17 +/- 16 months (range, 1-54 months) for TFX and 21 +/- 21 months (range, 1-97 months) for IFX. Mean serum Cr concentration increased significantly during long-term follow-up in both groups (TFX, 1.3 +/- 0.5 mg/dL to 1.5 +/- 0.8 mg/dL, P <.01; IFX, 1.3 +/- 0.7 mg/dL to 1.4 +/- 0.8 mg/dL, P <.03). Creatinine clearance (CrCl) similarly decreased over long-term follow-up in both groups (TFX, 53.3 +/- 17.7 mL/min/1.73 m(2) to 47.9 +/- 16.2 mL/min/1.73 m(2), P <.01; IFX, 58.1 +/- 22.7 mL/min/1.73 m(2) to 53.1 +/- 23.4 mL/min/1.73 m(2), P <.02). There were no significant differences in the increase in Cr concentration (P =.19) or decrease in CrCl (P =.68) between TFX and IFX groups. Small renal infarcts were noted in four patients (5.8%) in the TFX group and one patient (1.6%) in the IFX group. No increase in Cr concentration or decrease in CrCl was noted in any patient with a renal infarct. Postoperative renal dysfunction developed in 7 of 69 patients (10.1%) in the TFX group and 7 of 61 patients (11.5%) in the IFX group. There were no statistically significant differences between groups with respect to number of patients with new renal infarcts (P =.37) or postoperative renal dysfunction (P =.81). CONCLUSION: There is a slight increase in serum Cr concentration and decrease in CrCl after aortic endografting. However, there was no significant difference in these changes between patients with TFX and IFX. Although TFX may produce a higher incidence of small renal infarcts, these do not impair renal function. Thus our midterm results suggest that TFX can be performed safely, with no greater change in renal function than observed after IFX.     

Biomechanical study on pullout strength of thoracic extrapedicular screw fixation

Objective:To identify the biomechanical feasibility of the thoracic extrapedicular approach to the placement of screws. Methods:Five fresh adult cadaveric thoracic spine from T1 to T8 were harvested. The screw was inserted either by pedicular approach or extrapedicular approach. The result was observed and the pullout strength by pedicular screw approach and extrapedicular screw approach via sagittal axis of the vertebrale was measured and compared statistically. Results:In thoracic pedicular approach, the pullout strength of pedicle screw was 1001.23 N±220 N (288.2-1561.7 N) and that of thoracic extrapedicular screw approach was 827.01 N±260 N when screw was inserted into the vertebrae through transverse process,and 954.25 N±254 N when screw was inserted into the vertebrae through the lateral cortex of the pedicle. Compared with pedicular group, the pullout strength in extrapedicular group was decreased by 4.7% inserted through transverse process (P>0.05) and by 17.3% inserted through the lateral cortex (P<0.05). The mean pullout strength by extrapedicular approach was decreased by 11.04% as compared with pedicular approach (P<0.05). Conclusions:It is feasible biomechanically to use extrapedicular screw technique to insert pedicular screws in the thoracic spine when it is hard to insert by pedicular approach.     

The anatomical study of transoral atlantoaxial reduction plate internal fixation

Irreducibleanterioratlantoaxialdislocationwithventralspinalcordcompressionpresentsadifficultsurgicalchallenge.Nowasagenerallyacceptedoptionforthiscondition,decompressionthroughtransoralapproachhastobefollowedby anotheroperationwithinstrumentationandfusionofthe uppercervicalspinetoachievesegmentalstability.HarmsandKandziora1havedescribeddirectinternal platefixationsthroughtransoralapproach,buttheplate adoptedbyHarmsdidnothavealockingmechanism andtheplateusedbyKandziorafailedtoachieve immediate…     

Tibial Pilon fractures Internal plate fixation versus external wire fixation

A M ED LIN E search w as conducted to identify studiepublished betw een January 1998and January 2004usininternal plate fixation or external wire fixation for treatm ent of tibial Pilon fractures.The search strategy identified 20articles thatreportedoutcom…     

How long should outpatient pulmonary rehabilitation be? A randomised controlled trial of 4?weeks versus 7?weeks

BACKGROUND: The evidence of benefit for pulmonary rehabilitation (PR) programmes is established. However, the optimal duration of a PR programme is not known. A randomised controlled trial was undertaken in patients with chronic obstructive pulmonary disease (COPD) to assess whether a 4 week PR programme was equivalent to our conventional 7 week PR programme at equivalent time points of 7 weeks and 6 months. METHODS: One hundred patients (56 men) with stable COPD of mean (SD) age 70 (8) years and forced expiratory volume in 1 second (FEV1) 1.13 (0.50) litres were randomised to either a 7 week (n = 50) or 4 week (n = 50) supervised PR programme. Patients were assessed at baseline, at completion of the supervised PR programme, and 6 months later. Patients randomised to the 4 week group were also assessed at the 7 week time point. Outcome measures were the Incremental Shuttle Walk Test, Endurance Shuttle Walk Test (ESWT), Chronic Respiratory Questionnaire-Self Reported, and the Breathing Problems Questionnaire. RESULTS: Forty one patients in each group completed the PR programme. Patients made significant within group improvements after supervised rehabilitation. There were no statistically significant differences between the groups for any other measure at the 7 week or 6 month time points, except that patients in the 4 week group attained higher ESWT times (mean difference 124 seconds (95% CI 17.00 to 232.16), p = 0.024) at the 7 week time point. CONCLUSIONS: A shortened 4 week supervised PR programme is equivalent to a 7 week supervised PR programme at the comparable time points of 7 weeks and 6 months.