Analysis of complications in 97 periprosthetic Vancouver B2 fractures treated either by internal fixation or revision arthroplasty.

INTRODUCTION: The treatment of Vancouver B2 periprosthetic fractures after hip arthroplasty is still a matter of debate. Revision Arthroplasty (RA) was long thought to be the treatment of choice, however several recent papers suggested that Open Reduction and Internal Fixation (ORIF) is a viable option for selected B2 fractures. Complication rates of 14-26% have been reported following surgical treatment of B2 fractures. No significant difference between RA and ORIF in the complication rates nor in the functional outcome was observed. METHOD: We conducted a retrospective analysis of 97 consecutive Vancouver B2 fractures treated according to the algorithm at our institution from 2007 to 2020 and recorded complications and patient specific data. RESULT: From the 97 patient, 45 fractures were treated with RA while 52 fractures were treated with ORIF. Thirteen patients in the RA group had a complication that needed revision (28%) and 11 patients in the ORIF group needed revision (21%). There was no significant difference between complication rates. The reason for failure in the 13 RA patients were infection (n = 4), stem subsidence (n = 1), refracture after a new fall (n = 3), secondary dislocation of the greater trochanter (n = 1) and dislocation (n = 4). The reason for failure in the 11 ORIF patients that were revised were infection (n = 5), persistent symptomatic stem loosening (n = 3) and refracture (n = 3) after a new fall. CONCLUSION: ORIF can be used to revise cemented and non-cemented shafts in more than half of Vancouver B2 fractures with no difference in complication rates when compared to RA. A periprosthetic fracture around the hip has a 21-28% risk of a re-operation after revision surgery with infection and re-fracture after a new fall being the most frequent cause of re-operation.

Standardized artificially created stable pertrochanteric femur fractures present more homogenous results compared to osteotomies for orthopaedic implant testing.

BACKGROUND: With regard to biomechanical testing of orthopaedic implants, there is no consensus on whether artificial creation of standardized bone fractures or their simulation by means of osteotomies result in more realistic outcomes. Therefore, the aim of this study was to artificially create and analyze in an appropriate setting the biomechanical behavior of standardized stable pertrochanteric fractures versus their simulation via osteotomizing. METHODS: Eight pairs of fresh-frozen human cadaveric femora aged 72.7 ± 14.9 years (range 48-89 years) were assigned in paired fashion to two study groups. In Group 1, stable pertrochanteric fractures AO/OTA 31-A1 were artificially created via constant force application on the anterior cortex of the femur through a blunt guillotine blade. The same fracture type was simulated in Group 2 by means of osteotomies. All femora were implanted with a dynamic hip screw and biomechanically tested in 20° adduction under progressively increasing physiologic cyclic axial loading at 2 Hz, starting at 500 N and increasing at a rate of 0.1 N/cycle. Femoral head fragment movements with respect to the shaft were monitored by means of optical motion tracking. RESULTS: Cycles/failure load at 15° varus deformation, 10 mm leg shortening and 15° femoral head rotation around neck axis were 11324 ± 848/1632.4 ± 584.8 N, 11052 ± 1573/1605.2 ± 657.3 N and 11849 ± 1120/1684.9 ± 612.0 N in Group 1, and 10971 ± 2019/1597.1 ± 701.9 N, 10681 ± 1868/1568.1 ± 686.8 N and 10017 ± 4081/1501.7 ± 908.1 N in Group 2, respectively, with no significant differences between the two groups, p ≥ 0.233. CONCLUSION: From a biomechanical perspective, by resulting in more consistent outcomes under dynamic loading, standardized artificial stable pertrochanteric femur fracture creation may be more suitable for orthopaedic implant testing compared to osteotomizing the bone.

Direct anterior approach to the hip joint in the lateral decubitus position for joint replacement.

SURGICAL PRINCIPLE AND OBJECTIVE: The direct anterior approach for total hip arthroplasty is associated with higher complication rates and difficult femoral component positioning. Performing a modified technique in the lateral position allows secure component positioning. INDICATIONS: Primary hip replacement (including femoral neck fracture) and cup revision without bone deficiency. CONTRAINDICATIONS: Destruction/deformities of proximal femur or acetabulum, bone deficiency or malignancy. SURGICAL TECHNIQUE: Strict lateral decubitus position. Straight anterior incision of 10-12 cm, starting 2 cm lateral to the anterior superior iliac spine. Incision of the fascia over the tensor fascia lata muscle (TFL). Lateral retraction of the TFL. Incision of the fascia and medial retraction of rectus femoris. Ligation of the ascending branch of the lateral femoral circumflex artery. Detachment of the iliocapsularis muscle from the capsule in a medial direction. Anterior capsule excision. Femoral neck osteotomy and removal of the head. Reaming of the acetabulum; insertion the acetabular component. Exposure of the femur. Incision/excision of the capsule medial to the greater trochanter for easy anteriorization of the femur. Reaming and implantation of femoral component. POSTOPERATIVE MANAGEMENT: Weight bearing on day one with crutches for 4 weeks; deep vein thrombosis prophylaxis. RESULTS: In all, 138 patients (72 women, 66 men, mean age of 67 years) were followed up over 2 years. Overall complication rate was 3.6%: 3 patients (2.2%) with grade III complications required additional intervention. Acetabular cup inclination: 35-50° in 88% of patients. Neutral femoral stem position observed in 99% of patients. Mean Harris hip score improved from 61 preoperatively to 97 after 2 years. Patient satisfaction on a visual analogue scale improved from 3.7 to 9.5.

Angular stable lateral plating is a valid alternative to conventional plate fixation in the proximal phalanx. A biomechanical study.

BACKGROUND: Dorsal plating is commonly used in proximal phalanx fractures but it bears the risk of interfering with the extensor apparatus. In this study, dorsal and lateral plating fixation methods are compared to assess biomechanical differences using conventional 1.5mm non-locking plates and novel 1.3mm lateral locking plates. METHODS: Twenty-four fresh frozen human cadaveric proximal phalanges were equally divided into four groups. An osteotomy was set at the proximal metaphyseal-diaphyseal junction and fixed with either dorsal (group A) or lateral (group B) plating using a 1.5mm non-locking plate, or lateral plating with a novel 1.3mm locking plate with bicortical (group C) or unicortical (group D) screws. The specimens were loaded in axial, dorsovolar and mediolateral direction to assess fixation stiffness followed by a cyclic destructive test in dorsovolar loading direction. FINDINGS: Axial stiffness was highest in group D (mean 321.02, SEM 21.47N/mm) with a significant difference between groups D and B (P=0.033). Locking plates (groups C and D) were stiffer than non-locking plates under mediolateral loading (P=0.007), no significant differences were noted under dorsovolar loading. Furthermore, no significant differences were observed under cyclic loading to failure between any of the study groups. INTERPRETATION: No considerable biomechanical advantage of using a conventional 1.5mm dorsal non-locking plate was identified over the novel 1.3mm lateral locking plate in the treatment of proximal phalanx fractures. Since the novel low-profile plate is less disruptive to the extensor mechanism, it should be considered as a valid alternative.

Biomechanical evaluation of interfragmentary compression at tibia plateau fractures in vitro using different fixation techniques: a CONSORT-compliant article.

Reliable osteosynthesis of intraarticular fractures depends on lasting interfragmentary compression. Its amount differs in the applied fixation method. The interfragmentary compression of cancellous and cortical lag screws and angle stable locking plates was quantified in an osteoporotic and non-osteoporotic synthetic human bone model.A split fracture of the lateral tibia plateau (AO/OTA type 41-B1.1) was mimicked by an osteotomy in right adult synthetic human tibiae with hard or soft cancellous bone. Specimens were fixed with either two 6.5 mm cancellous, four 3.5 mm cortical lag screws, or 3.5 mm LCP proximal lateral tibia plate preliminary compresed by a reduction clamp (n = 5 per group). A pressure sensor film was used to register the interfragmentary compression. One-way analysis of variance (ANOVA) with Bonferroni post hoc correction was performed for statistical analysis (p < 0.05).Interfragmentary compression under reduction clamp was 0.59 ±â€Š0.12 MPa in the non-osteoporotic and 0.55 ±â€Š0.14 MPa in the osteoporotic group. The locking plate itself maintained the compression in non-osteoporotic (0.53 ±â€Š0.11 MPa) and osteoporotic bone (0.50 ±â€Š0.14 MPa). Four 3.5 mm cortical lag screws provided a compression of 1.69 ±â€Š0.65 MPa in non-osteoporotic bone, being not significantly different to the osteoporotic bone group (1.43 ±â€Š0.47 MPa, P = 1.0). Two 6.5 mm cancellous lag screws showed a significantly higher compression in non-osteoporotic (2.1 ±â€Š0.59 MPa) compared to osteoporotic (0.77 ±â€Š0.21 MPa, P < 0.01) bone.Angle stable locking plates maintained the compression preliminarily applied by a reduction clamp. Two 6.5 mm cancellous lag screws are especially suited for non-osteoporotic bone, whereas four 3.5 mm cortical screws exhibited comparable compression in both bone qualities.

[Chronic ankle joint instability: in unrecognized distal rupture of the syndosmosis and malunion of the distal fibula]. / Chronische obere Sprunggelenkinstabilität : Bei nicht erkannter distaler Syndesmosenruptur und Malunion der Fibulaspitze.

BACKGROUND: It is often difficult in the acute phase to diagnose a lesion of the distal tibiofibular syndesmosis. If this lesion is overlooked, the patient will develop an incongruity of the upper ankle joint with a pathological external rotation of the talus. The risk of a possible premature arthritis is clearly increased. OBJECTIVES: In this case study a distal rupture of the syndesmosis in a young patient was overlooked in the initial diagnostic work-up. METHODS: A search of the relevant literature and a case report. RESULTS: In the case described the shortened fibula and chronic instability of the tibiofibular syndesmosis were repaired with a lengthening and derotational osteotomy and reconstruction using the gracilis muscle tendon. Through this method an exact reconstruction of the normal anatomy could be achieved. CONCLUSION: Posttraumatic misalignment in the ankle joint is associated with a high risk of secondary degenerative lesions. In cases with suspicion of a syndesmosis lesion, confirmation of the diagnosis is imperative so as to perform an anatomic repositioning and reconstruction of stability.

Early results in the treatment of proximal humeral fractures with a polyaxial locking plate.

OBJECTIVES: We report early results using a second generation locking plate, non-contact bridging plate (NCB PH((R)), Zimmer Inc. Warsaw, IN, USA), for the treatment of proximal humeral fractures. The NCB PH combines conventional plating technique with polyaxial screw placement and angular stability. DESIGN: Prospective case series. SETTING: A single level-1 trauma center. PATIENTS: A total of 50 patients with proximal humeral fractures were treated from May 2004 to December 2005. INTERVENTION: Surgery was performed in open technique in all cases. MAIN OUTCOME MEASURES: Implant-related complications, clinical parameters (duration of surgery, range of motion, Constant-Murley Score, subjective patient satisfaction, complications) and radiographic evaluation [union, implant loosening, implant-related complications and avascular necrosis (AVN) of the humeral head] at 6, 12 and 24 weeks. RESULTS: All fractures available to follow-up (48 of 50) went to union within the follow-up period of 6 months. One patient was lost to follow-up, one patient died of a cause unrelated to the trauma, four patients developed AVN with cutout, one patient had implant loosening, three patients experienced cutout and one patient had an axillary nerve lesion (onset unknown). The average age- and gender-related Constant Score (n = 35) was 76. CONCLUSIONS: The NCB PH combines conventional plating technique with polyaxial screw placement and angular stability. Although the complication rate was 19%, with a reoperation rate of 12%, the early results show that the NCB PH is a safe implant for the treatment of proximal humeral fractures.

Removal of the well-fixed hip resurfacing acetabular component: a simple, bone preserving technique.

Removal of the acetabular component of a hip resurfacing prosthesis is occasionally necessary for infection, malposition, metal sensitivity, wear, or as a necessary part of a femoral revision. Extraction of a well-fixed acetabular component can be technically demanding as it is often extremely well integrated into host bone and can result in catastrophic bone loss or fracture. We present an undescribed, simple technique that enables use of the Explant system (Zimmer, Warsaw, Ind) to remove the component with minimal bone loss and reduce fracture risk. Bone stock is therefore preserved for subsequent cup reimplantation.

Tibio-femoral cartilage defects 3-5 years following arthroscopic partial medial meniscectomy.

OBJECTIVE: Arthroscopic partial medial meniscectomy (APMM) is a common procedure to treat a medial meniscal tear. Individuals who undergo APMM have a heightened risk of developing tibio-femoral osteoarthritis (OA). Cartilage defects scored from magnetic resonance imaging (MRI) scans predict cartilage loss over time. It is not known whether cartilage defects in the early years following APMM are more common or of greater severity than in age-matched controls. This study compared the prevalence and severity of tibio-femoral cartilage defects in patients 3-5 years post-APMM with that of age-matched controls. METHODS: Twenty-five individuals who had undergone APMM in the previous 46.9+/-5.0 months and 24 age-matched controls participated in this study. Sagittal plane knee MRI scans were acquired from the operated knees of patients and from randomly assigned knees of the controls and graded (0-4) for tibio-femoral cartilage defects. Defect prevalence (score of >or=2 for any compartment) and severity of the cartilage from both tibio-femoral compartments were compared between the groups. RESULTS: The APMM group had greater prevalence (77 vs 42%, P=0.012) and severity (4.1+/-1.9 vs 2.8+/-1.1, P=0.005) of tibio-femoral cartilage defects than controls. Age was positively associated with tibio-femoral cartilage defect severity for APMM, r=0.523, P=0.007, but not for controls, r=0.045, P=0.834. CONCLUSION: Tibio-femoral joint cartilage defects are more prevalent and of greater severity in individuals who had undergone APMM approximately 44 months earlier than in age-matched controls.

The SLAP lesion as a reason for glenolabral cysts: a report of five cases and review of the literature.

INTRODUCTION: Cysts in the spinoglenoidal or supraglenoidal incisura can be a cause of compression of the suprascapular nerve. There is agglomerated appearance of these cysts in combination with SLAP lesions. Hypothesis is SLAP lesions can lead to cysts in this region and should be repaired. MATERIAL AND METHODS: MRI of five patients (all male, four 30-40 years, one 75 years) showed cysts in the supralabral region. All were in combination with lesions of the superior glenoidal labrum (Type II or more). RESULTS: In two cases, in addition to cyst resection, the SLAP lesion was also repaired and symptoms disappeared completely and no recurrent cyst was detected in postoperative MRI. Two patients without SLAP repair showed recurrent cystic formation in MRI with similar complaints compared to their preoperative status. One patient (75 years) was treated primarily by puncture and afterwards with open resection of the cyst. His outcome was good in terms of activities of daily living without major pain. CONCLUSIONS: Our results are based on the assumption that cysts in the region of the spinoglenoidal/supraglenoidal incisura can originate from SLAP lesions. If a patient is suspected of having cysts in this region, the question of a SLAP lesion should be clarified. SLAP lesions should be repaired to avoid relapse. Arthroscopic repair of SLAP lesion can lead to the disappearance of symptoms in younger patients. In older patients puncture or resection of the ganglion alone may be an adequate therapeutic strategy.

Fatigue of the cement/bone interface: the surface texture of bone and loosening.

Loosening is recognized as one of the primary sources of total hip replacement (THR) failure. In this study the influence of the bone surface texture on loosening of the cement/bone interface was studied. Model cemented hip replacements were prepared and subjected to cyclic loads that induced pure shear fatigue of the cement/bone interface. The femoral canals were textured with the use of specific cutting tools to achieve a desired surface topography. Loosening of the implant with cyclic loading was characterized in terms of the initial migration (Region I), steady-state loosening (Region II), and unstable loosening (Region III). Results from the experiments showed that the initial migration and rate of steady-state loosening were dependent upon the bone surface topography. The apparent fatigue strength ranged from 0.8 to 5.1 MPa, and denotes the cyclic shear stress required for loosening of 1 mm within 10 million cycles. Regardless of the bone surface topography the ratio of apparent fatigue strength and ultimate shear strength of the interfaces was approximately 0.24. In general, the apparent fatigue strength increased proportional to the average surface roughness of the femoral canal and the corresponding volume available for cement interdigitation. In addition, there was a strong correlation between the normalized initial migration and the apparent fatigue strength (i.e., specimens with the highest initial migration exhibited the lowest fatigue strength).

The apparent volume of interdigitation: a new parameter for evaluating the influence of surface topography on mechanical interlock.

A new parameter has been defined to estimate the apparent volume of interdigitation (V(i)) that is available from a surface to support mechanical interlock. The parameter is estimated in terms of the core roughness parameters, which can be obtained from the material ratio curve of a representative surface profile. A verification of the definition for V(i) is performed with the use of ideal surface profiles consisting of Gaussian and skewed height distributions. In contrast to conventional surface roughness parameters, the expression for V(i) is capable of differentiating between positive and negative skewed surfaces with the same average surface roughness. It is expected that V(i) will be a useful tool for optimization of the prosthesis and bone surface topographies, which are essential to the long-term success of cemented total joint replacements.

Functional load of plates in fracture fixation in vivo and its correlate in bone healing.

In clinical practice efforts are made to apply a fixation plate on the side opposite the strongest muscle pull. This achieves an optimal distribution of compression between the fragment ends (principle of tension band plating). This is however frequently impossible for anatomical or surgical reasons. In an 'in vivo' study lasting 8 weeks a standardized oblique osteotomy was performed on the tibia of 16 sheep in four different models of tension band plating (a contoured and an overbent plate with or without an interfragmentary lag screw) were assessed. Tension on the plate surface was recorded by strain gauges for different gait speeds on the treadmill. These measurements were performed throughout the experiment. Radiographs were taken at regular intervals in order to assess stability and polychrome sequential labelling and microradiographs served to investigate the healing process. Possible relationships and/or interactions between plate tension and bone healing were investigated. Implant loading under bending strain was reduced the most for the combination of plate overbending with a lag screw. The insertion of a lag screw reduces the surface strain on the plate whether it is contoured or overbent. The bending and torsional forces are greatest if a straight plate is used alone and the principle of tension band plating is not applied. Direct bone healing was only observed in the group with contoured plate and lag screw. Overbending combined with a lag screw provided only a relatively unstable fixation. A residual gap immediately beneath the plate permits "dynamic compression" since the screws slide towards the osteotomy when loaded producing bone resorption under the plate and signs of screw loosening. The models with contoured and overbent plates without a lag screw were histologically assessed as very unstable with signs of secondary fragment displacement, obvious callus formation, resorption at the fragment ends and under the plate, delayed and diminished Haversian remodelling and corrosion sites at the screw heads and at the adjacent site on the plate hole. In all groups, stripping of the periosteum under the plate was associated with porosis of the corresponding cortex as a sign of temporarily impaired blood supply. A relationship between implant loading and/or unloading (stress shielding) could not be demonstrated. Callus formation, measured quantitatively on the radiographs, is directly related to the strain on the plate. Direct bone healing is rapid and is seen histologically three weeks postoperatively, particularly for fixations with contoured plate and lag screw. The early appearance of fixation callus in the presence of an intact blood supply indicates a primary instability of the osteosynthesis. Later, it may be an indication of secondary instability. The time at which osteons appear, their number and location provides information on the stability of the osteosynthesis. At a time when indirect fracture reduction and stabilization using minimally invasive techniques and implants is being propagated, additional ways and means must be sought to assess clinically the load on the implants and the risk of implant failure.

[Relevant differences after post-traumatic and degenerative humeral head replacement (intermediate-term results)]. / Relevante Unterschiede nach posttraumatischem und degenerativem Humeruskopfersatz (mittelfristige Resultate).

INTRODUCTION: In a comparative study, mid-term findings after posttraumatic and degenerative hemi-prosthetic shoulder joint replacement were analyzed and compared with current reports in the literature. METHODS: The patient sample in the retrospective study consisted of 20 patients with proximal fractures of the humeral head (x = 64 years) and 6 patients (x = 61 years) with degenerative shoulder joint disease. In 14 patients the humeral head was replaced as a primary procedure at < 4 weeks after the trauma and in 6 patients as a secondary treatment at > 4 weeks. The follow-up period was 38-41 months on average. Evaluation was based on the Constant Score, subjective assessment by the patient, and conventional radiographs. RESULTS: After posttraumatic shoulder replacement, the patients achieved a Constant Score of 65 (+/- 19) and after degenerative replacement 74 (+/- 34) points. In the posttraumatic group, the Constant Score after primary implantation was better than after secondary implantation (68 +/- 16 versus 59 +/- 15 points). After posttraumatic replacement, the only improvement over time was in pain levels (p < 0.05). 92% of all patients were satisfied with the result and would accept the same treatment again. Radiologically, a clinical correlate could be found for the arrosions at the acromion and occasionally for the secondary upwards displacement of the humerus. The results correlated well with data from the literature. CONCLUSIONS: For posttraumatic conditions, hemiarthroplasty led to better results within four weeks and seemed to be a suitable alternative to other procedures, especially in older patients. Patients with primary osteoarthritis and idiopathic humeral head necrosis can expect good to excellent results after hemiarthroplasty. In both groups, the overall results depend mainly upon patient compliance and the state of the rotator cuff.

A graphical tool for ad hoc query generation.

Medical data are characterized by complex taxonomies and evolving terminology. Questions that clinicians, medical administrators, and researchers may wish to answer using medical databases are not easily formulated as SQL queries. In this paper we describe a graphical tool that facilitates formulation of ad hoc questions as SQL queries. This tool manages multiple attribute hierarchies and creates SQL query strings by navigating through the hierarchies. This interactive tool has been optimized using indexing to improve the overall speed of the query building and the data retrieval process. Indexed queries performed 5 to 100 times faster than query strings. However, query string generation time depends on the size of the taxonomies describing the hierarchies, while the index generation time depends on the size of the data warehouse.

[Quantification of the intra-penile smooth muscle with a fuzzy logic algorithm]. / Quantification de la musculature lisse intrapénienne avec un algorithme de logique floue.

We have developed a new computer program for tissue segmentation designed for the quantification of smooth muscle in the corpus cavernosum. The program uses digitalized images of stained histological sections taken with a CCD camera. The recognition of the different tissues is based on the examination of absorption of monochromatic light. The section is successively illuminated with light of three different wavelengths and the three absorption values and texture parameters are used for the identification of the tissue using a fuzzy algorithm.