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author:("haaster, Carl")
1.  Overweight and obesity in hip and knee arthroplasty: Evaluation of 6078 cases 
World Journal of Orthopedics  2015;6(1):137-144.
AIM: To evaluate a possible association between the various levels of obesity and peri-operative charac-teristics of the procedure in patients who underwent endoprosthetic joint replacement in hip and knee joints.
METHODS: We hypothesized that obese patients were treated for later stage of osteoarthritis, that more conservative implants were used, and the intra-and perioperative complications increased for such patients. We evaluated all patients with body mass index (BMI) ≥ 25 who were treated in our institution from January 2011 to September 2013 for a primary total hip arthroplasty (THA) or total knee arthroplasty (TKA). Patients were split up by the levels of obesity according to the classification of the World Health Organization. Average age at the time of primary arthroplasty, preoperative Harris Hip Score (HHS), Hospital for Special Surgery score (HSS), gender, type of implanted prosthesis, and intra-and postoperative complications were evaluated.
RESULTS: Six thousand and seventy-eight patients with a BMI ≥ 25 were treated with a primary THA or TKA. Age decreased significantly (P < 0.001) by increasing obesity in both the THA and TKA. HHS and HSS were at significantly lower levels at the time of treatment in the super-obese population (P < 0.001). Distribution patterns of the type of endoprostheses used changed with an increasing BMI. Peri- and postoperative complications were similar in form and quantity to those of the normal population.
CONCLUSION: Higher BMI leads to endoprosthetic treat-ment in younger age, which is carried out at significantly lower levels of preoperative joint function.
PMCID: PMC4303782  PMID: 25621218
Adiposity; Total knee arthroplasty; Total hip arthroplasty; Obesity; Overweight; Prosthesis
2.  Treatment of osteochondral fractures of the knee: a meta-analysis of available scientific evidence 
International Orthopaedics  2013;37(12):2385-2394.
Although traumatic osteochondral fractures of the knee represent a common pathology of the knee joint, there is no general agreement concerning specific treatment of this entity. This meta-analysis was initiated in order to evaluate scientific evidence on different treatment options for acute osteochondral fractures of the knee.
For this purpose an OVID-based systematic literature search was performed including the following databases: MEDLINE, MEDLINE preprints, Embase, CINAHL, Life Science Citations, British National Library of Health and Cochrane Central Register of Controlled Trials. The literature search period was from 1946 to January 2012, which led to the identification of 1,226 articles. After applying study-specific inclusion criteria a total of 19 studies with clinical follow-up of 638 patients were included. The methodology of these studies was systematically analysed by means of the Coleman Methodology Score. Outcome and success rates were evaluated depending on treatment applied.
All studies (n = 19) identified represent case series (evidence-based medicine level IV) and included a total of 638 patients. The average post-operative follow-up was 46 ± 27 months (range 3.75–108). The mean number of study subjects per study was 33 ± 44 patients (range 4–169). The average Coleman Methodology Score was 29 ± 17 points (range 5–72). Six different scoring systems were used for clinical assessment. The overall clinical success rate was 83 % and varied between 45 and 100 %.
This meta-analysis reveals a significant lack of scientific evidence for treatment of osteochondral fractures of the knee. No valid conclusion can be drawn from this study concerning the recommendation of a specific treatment algorithm. Nevertheless, the overall failure rate of 17 % underlines that an acute osteochondral fracture of the knee represents an important pathology which is not a self-limiting injury and needs further investigation.
PMCID: PMC3843186  PMID: 24022737
Osteochondral fractures of the knee; Meta-analysis; No valid conclusions; High failure rate
3.  Enhanced migration of human bone marrow stromal cells in modified collagen hydrogels 
International Orthopaedics  2013;37(8):1605-1611.
Collagen I hydrogels are widely used as scaffolds for regeneration of articular cartilage defects. We hypothesised that ingrowth might be improved by removing the superficial layer of a compressed hydrogel. The control group consisted of the original unmodified product.
The migration of human bone marrow stromal cells (hBMSCs) into the hydrogel was evaluated by confocal microscopy. We quantified the DNA concentration of the hydrogel for each group and time point and evaluated the chondrogenic differentiation of cells.
After one week, the detectable amount of cells at the depth of 26–50 μm was significantly higher in the modified matrix (MM) than in the non-modified matrix (NM) (p = 0.011). The maximum depth of penetration was 75 μm (NM) and 200 μm (MM). After three weeks, the maximum depth of penetration was 175 μm (NM) and 200 μm (MM). Likewise, at a depth of 0–25 μm the amount of detectable cells was significantly higher in the MM group (p = 0.003). After 14 days, the concentration of DNA was significantly higher in the samples of the MM than in the control group (p = 0.000). Staining of histological sections and labelling with collagen II antibodies showed that a chondrogenic differentiation of cells in the scaffold can occur during in vitro cultivation.
Removing the superficial layer is essential to ensuring proper ingrowth of cells within the compressed hydrogel. Compressed hydrogels contribute better to cartilage regeneration after surface modification.
PMCID: PMC3728398  PMID: 23645081
4.  Traumatic Stem Fractures in Short Stem THA-A Rare Case Series 
HSS Journal  2012;9(1):86-89.
Adequate trauma of a well-fixed total hip prosthesis might cause relevant osseous injuries. Concomitant occult fractures of the implant itself are very rare. We report on two patients admitted to our institution and who were previously treated with similar types of short-stem total hip arthroplasty (THA). Both were unable to walk after an adequate trauma, although the initial admitting hospital misdiagnosed the exact diagnosis. Detailed reexamination later revealed a prosthetic neck fracture of the cement-free stem. Both patients were treated with a stem revision. In THA patient, special attention should be drawn to the implants after relevant trauma. A single examination shortly after trauma seems to be insufficient to diagnose implant-related injuries. A secondary follow-up several weeks after trauma, including at least X-rays, has to be recommended.
PMCID: PMC3640711  PMID: 24426849
hip; arthroplasty; implant failure
5.  Near-Infrared Spectroscopy Correlates with Established Histological Scores in a Miniature Pig Model of Cartilage Regeneration 
Near-Infrared Spectroscopy (NIRS) could be of clinical relevance in modern cartilage regeneration.In a miniature pig model correlation of measurements and histologic scores have never been used before. The data analysis was part of an animal project that investigated the effects of seeding a chondrogenic and osteogenic scaffold with a bone-marrow-derived cell concentrate and reports the histological and mechanical properties. We created 20 osteochondral defects in the femoral condyles of 10 miniature pigs.The defects were left empty (E), filled with the grafted cylinder upside down (U), or with a combined scaffold (S) containing a spongy bone cylinder covered with a collagen membrane. In the fourth group, the same scaffolds were implanted but seeded with a stem cell concentrate (S+BMCC). The animals were euthanized after 3 months, and histologic and spectrometric analyses were performed. NIRS measurements were significantly higher in the central area of the defects of group S+BMCC compared to the central area of the defects of group U. In all groups, a correlation between NIRS and the histologic scores could be demonstrated though on different levels. In the central area, a good NIRS measurement correlates with low (good) histologic scores. In group E and group S, this negative correlation was significant (p=0.01). For the first time, NIRS was successfully used to evaluate osteochondral constructs in a miniature pig model.
PMCID: PMC4040933  PMID: 24895022
Cartilage; miniature pig; near-infrared spectroscopy; NIRS; steochondral lesion; Pineda; Wakitani.
6.  Reconstruction of Osteochondral Defects by Combined Bone Grafting and a Bilayer Collagen Membrane as a Sandwich Technique 
Orthopedic Reviews  2013;5(4):e36.
Treatment of osteochondral lesions of the knee remains a major challenge in orthopedic surgery. Recently established procedures like autologous chondrocyte implantation or matrix-associated chondrocyte implantation yield good results, but include the disadvantage of two-step procedures. The purpose of this study was to evaluate the clinical and magnetic resonance imaging outcome of repairs of osteochondral defects of the knee by a combined procedure of bone grafting and covering with a bilayer collagen membrane in a sandwich technique. Seven male patients with a mean age of 42 (range 30-55) years and symptomatic focal osteochondral lesions of the knee grade IV according to the International Cartilage Repair Society classification were included. The mean diameter of defects was 28.6 (range 15-40) mm. Results were evaluated at a minimum of 24 months after surgery by International Knee Documentation Committee score, Lysholm-score, visual analogue scale, and magnetic resonance imaging with specific cartilage sequences, evaluating the ICRS score and the Magnetic Observation of Cartilage Repair Tissue (MOCART) score. All patients judged the operation as successful. Among the patients available for the long-term follow-up, mean visual analogue scale value was 1.3 (range 0-3) out of 10 points. Mean International Knee Documentation Committee score was 80.8 (range 63.2-88.5) out of 100 points. Mean Lysholm score was 85 (range 55-95) out of 100 points. None of the patients had to be reoperated until today. Evaluation of magnetic resonance imaging using the MOCART score revealed a good correlation to the clinical outcome. This is the first study reporting results after reconstruction of osteochondral defects of the knee joint by bone grafting and a bilayer collagen membrane. This new method offers the advantage of a one-step-procedure and yields both good clinical and magnetic resonance findings. We conclude that this procedure can be a valuable tool to improve joint function after osteochondral defects, trauma, and in joints with local arthritic lesions.
PMCID: PMC3883077  PMID: 24416480
knee; osteochondral defects; cartilage repair; regenerative joint surgery; magnetic resonance imaging; MOCART score
7.  Histological ex vivo analysis of retrieved human tantalum augmentations 
International Orthopaedics  2012;36(11):2269-2274.
The characteristics of tantalum augment osseointegration in human ex vivo specimens from re-revision procedures are unknown and limited data in this regard is available. The purpose of this study was to investigate the osseointegration pattern into porous tantalum augmentations harvested during re-revision procedures.
Between 2007 and 2010 a total of 324 hip and knee revisions with a tantalum augmentation were performed in our institution. Out of this cohort, seven patients (2.2 %) had to be re-revised. To analyse the status of trabecular ingrowth in the retrieved cases (four hips, three knees), all specimens were analysed by contact radiography, subjected to undecalcified processing, histology, thin-section analysis and backscattered electron imaging.
Trabecular and vascular ingrowth could be found along the bone-augment-interface in two of seven revised specimens, respectively. The depth of bone ingrowth reached up to 2.6 mm. However, the analysis of the remaining cases revealed no bony ingrowth into trabecular metal. Rather, large parts of the implants were embedded in cement or pores were filled with autologous bone.
Although the cause for the missing bony ingrowth seems to be multifactorial, some fundamental conditions, such as the provision of the greatest possible interface between the tantalum implant and the host bone, should be met and thus, bone cement and autologous bone grafts should be used with caution.
PMCID: PMC3479269  PMID: 22893376
8.  10-year results following impaction bone grafting of major bone defects in 29 rotational and hinged knee revision arthroplasties 
Acta Orthopaedica  2013;84(4):387-391.
Background and purpose
— Substantial bone loss in revision total knee arthroplasty (TKA) is a challenging problem. We studied whether impaction bone grafting provides long-term restoration of bone stock in the treatment of major bone defects in revision surgery of rotational and hinged knee arthroplasties (LINK Endo-Model).
Patients and methods
— Between 1996 and 2006, 29 knees in 29 patients underwent revision procedures of rotational and hinged knee arthroplasties using impaction bone grafting (IBG) to reconstruct major bone defects. At the latest follow-up, the clinical examination included the Knee Society score (KSS), standardized radiographs, and a questionnaire for the WOMAC score.
— After a mean follow-up of 10 (6–13) years, 14 knees with 19 IBG reconstructions (5 total, 9 partial revisions) had failed. 12 knees were treated with re-revision surgery mean 5 (1–12) years after the first revision, due to mechanical failure and aseptic loosening of the components. In all these failed cases, the surgeon observed a lack of incorporation with bone graft resorption in the femur or tibia during the re-revision procedure. In all 15 knees that were not re-revised, with 21 reconstructions (6 total, 9 partial revisions), an improvement in the combined KSS score (knee score + function score) of 60 points (p < 0.001) was found at the latest follow-up. In 12 of these knees, a clear incorporation with no visible radiolucent lines around the component and no sign of substantial graft resorption was noted, while unclear radiographic graft incorporation was seen in 3 knees.
— Our results clearly indicate that IBG alone is not a methodologically sound technique in the revision of rotational and hinged knee arthroplasties.
PMCID: PMC3768039  PMID: 23799350
10.  Eleven Year Results of Total Hip Arthroplasty in Patients with Secondary Osteoarthritis Due to Slipped Capital Femoral Epiphysis 
Total hip arthroplasty (THA) in patients with a history of Slipped Capital Femoral Epiphysis (SCFE), is typically indicated to address the consequent deformity of the proximal femur and/or acetabulum. It can be a challenging procedure for the orthopaedic surgeon. Previous studies have focused on prevention of osteoarthritis post-SCFE. However, there is a paucity of data on the outcomes of total hip arthroplasty in patients with osteoarthritis secondary to SCFE. This study was performed to assess the mid-term results of total hip arthroplasty in this patient cohort.
Materials and Methods:
All patients with secondary osteoarthritis due to slipped capital femoral epiphysis, treated with total hip arthroplasty between 1987 and 2005, were included in this retrospective study (n=30). Thirty patients (17 male, 13 female) met the inclusion criteria with one patient lost to follow-up and one unrelated death one year before follow up examination, thereby leaving 28 patients (32 hips) eligible for the study with a mean follow-up time period of 11.2 years. The Harris Hip Score (HHS) and MOS 36 short form health survey (SF36) were determined preoperatively and at most recent follow-up for all patients. Complications were also noted for all cases.
The mean Harris Hip Score increased significantly from 47 (32-59; SD=8.3) to 92.3 (65-100; SD=8.2) (p<0.0001). The SF-36 health survey showed an improvement of quality-of-life in all sub-scales. Overall, revision surgery was required in six cases (19 %). Aseptic loosening, leading to implant removal, was noted in five cases. A single-stage revision to address infection was performed in one case. The cumulative survival rate at latest follow-up was 81 %. No other complications were encountered during the study.
Despite a higher failure rate, compared to total hip arthroplasty in the treatment of primary osteoarthritis, total hip arthroplasty can be considered a feasible option for patients with secondary osteoarthritis of the hip due to slipped capital femoral epiphysis. The current study demonstrates good outcomes in patients treated with a cementless column-preserving prosthesis, which is of particular relevance for this young patient cohort. However, further clinical prospective randomized studies are warranted to provide more definitive evidence.
PMCID: PMC3664464  PMID: 23730379
Total hip arthroplasty; slipped capital femoral epiphysis.
11.  Intraprosthetic fixation techniques in the treatment of periprosthetic fractures-A biomechanical study 
World Journal of Orthopedics  2012;3(10):162-166.
AIM: To develop new fixation techniques for the treatment of periprosthetic fractures using intraprosthetic screw fixation with inserted threaded liners.
METHODS: A Vancouver B1 periprosthetic fracture was simulated in femur prosthesis constructs using sawbones and cemented regular straight hip stems. Fixation was then performed with either unicortical locked-screw plating using the less invasive stabilization system-plate or with intraprosthetic screw fixation using inserted liners. Two experimental groups were formed using either prostheses made of titanium alloy or prostheses made of cobalt chrome alloy. Fixation stability was compared in an axial load-to-failure model. Drilling was performed using a specially invented prosthesis drill with constantly applied internal cooling.
RESULTS: The intraprosthetic fixation model with titanium prostheses was superior to the unicortical locked-screw fixation in all tested devices. The intraprosthetic fixation model required 10 456 N ± 1892 N for failure and the unicortical locked-screw plating required 7649 N ± 653 N (P < 0.05). There was no significant difference between the second experimental group and the control group.
CONCLUSION: Intraprosthetic screw anchorage with special threaded liners enhances the primary stability in treating periprosthetic fractures by internal fixation.
PMCID: PMC3536858  PMID: 23326763
Periprosthetic fracture; Less invasive stabilization system; Plate fixation; Intraprosthetic screw fixation; Material science; Biomechanical testing; Axial load-to-failure
12.  Injury patterns of seniors in traffic accidents: A technical and medical analysis 
World Journal of Orthopedics  2012;3(9):151-155.
AIM: To investigate the actual injury situation of seniors in traffic accidents and to evaluate the different injury patterns.
METHODS: Injury data, environmental circumstances and crash circumstances of accidents were collected shortly after the accident event at the scene. With these data, a technical and medical analysis was performed, including Injury Severity Score, Abbreviated Injury Scale and Maximum Abbreviated Injury Scale. The method of data collection is named the German In-Depth Accident Study and can be seen as representative.
RESULTS: A total of 4430 injured seniors in traffic accidents were evaluated. The incidence of sustaining severe injuries to extremities, head and maxillofacial region was significantly higher in the group of elderly people compared to a younger age (P < 0.05). The number of accident-related injuries was higher in the group of seniors compared to other groups.
CONCLUSION: Seniors are more likely to be involved in traffic injuries and to sustain serious to severe injuries compared to other groups.
PMCID: PMC3502611  PMID: 23173111
Traffic accidents; Seniors; Head injury; Injury severity score; Abbreviated injury scale
13.  Knee injuries in severe trauma patients: a trauma registry study in 3.458 patients 
Purpose of the presented study is to answer the following questions: Are knee injuries associated with trauma mechanisms or concomitant injuries? Do injuries of the knee region aggravate treatment costs or prolong hospital stay in polytraumatized patients?
A retrospective analysis including 29.779 severely injured patients (Injury Severity Score [greater than or equal to] 16) from the Trauma Registry of the German Society for Trauma Surgery database (1993-2008) was conducted. Patients were subdivided into two groups; the "Knee" group (n=3.458, 11.6% of all patients) including all multiple trauma patients with knee injuries, and the "Non Knee" group (n=26.321) including the remaining patients. Patients with knee injuries were slightly younger, less often male gender and had a significantly increased ISS.
Patients in the Knee group suffered significantly more traffic accidents compared to the Non Knee group (82% vs. 52%, p<0.001). These injuries were more often caused by car or motorbike accidents. Severe thoracic and limb injuries (AIS[greater than or equal to]3) were more frequently found in the Knee group (p<0.001) while head injury was distributed equally. The overall hospital stay, ICU stay, and treatment costs were significantly higher for the Knee group (38.1 vs. 25.5 days, 15.2 vs. 11.4 days, 40,116 vs. 25,336 Euro, respectively; all p<0.001).
Traffic accidents are associated with an increased incidence of knee injuries than falls or attempted suicides. Furthermore, severe injuries of the limbs and chest are more common in polytraumatized patients with knee injuries. At last, treatment of these patients is prolonged and consequently more expensive.
PMCID: PMC3489801  PMID: 22866995
14.  Current state of computer-assisted trauma surgery 
Computer assisted surgery (CAS) was first used in neurosurgery. Currently, CAS has gained popularity in several surgical disciplines including urology and abdominal surgery. In trauma and orthopaedic surgery, computer assisted systems are used for fracture reduction, planning and positioning of implants as well as the accurate implantation of hip and knee prostheses. The patient’s anatomy is virtualized and the surgical instruments integrated into the digitized image background, thus allowing the surgeon to navigate the surgical instruments and the bone in an improved, virtual visual environment. CAS improves overall accuracy, reducing intraoperative radiation exposure and minimizing unnecessary surgical dissection combined with increased patient and surgeon safety. However, limitations include prolonged surgical time, technical errors and cost implications. This article will outline the current state of computer assisted trauma surgery including its implications and specific challenges in orthopaedic trauma surgery.
PMCID: PMC3535088  PMID: 22832946
Computer assisted surgery; Navigation; Trauma; SI-screw; Femur; Femoral malrotation
15.  Traumatic Ceramic Femoral Head Fracture: An Initial Misdiagnosis 
Background and Purpose:
Ceramic heads are widely used in modern total hip arthroplasty (THA). Although a rare complication, fractures of ceramic heads are described in the literature, evoking uncertainties regarding the in vivo stability of this material, especially when impaction of a fractured ceramic head can lead to disastrous results.
In this case report, we present a fracture of a ceramic head after trauma. A misinterpretation of the initial radiographs led to severe fragmentation of the ceramic head two weeks after the incident, later resulting in complete destruction of the arthroplasty.
Results and Interpretation:
Remarkably, radiographs obtained more than one year after the trauma led to this delayed diagnosis. A single radiographic evaluation, especially in patients with persistent pain after major trauma, with a ceramic head in a THA, seems to be insufficient
PMCID: PMC3426826  PMID: 22927896
Total hip arthroplasty; ceramic head fracture; misdiagnosis; complication; trauma; radiographic evaluation.
16.  Secondary Patellar Resurfacing after Primary Bicondylar Knee Arthroplasty did Not Meet Patients’ Expectations 
Secondary patella resurfacing is a controversial procedure which is applied in patients with anterior knee pain after a bicondylar knee arthroplasty (with unresurfaced patella). A group of 46 patients were submitted to this procedure and their satisfaction, range of motion and pain improvement was evaluated. 52.2% of the patients were satisfied with the procedure, with an improvement in pain (Visual Analogue Scale) of 65% and an improvement in range of motion in 56,5%, with roundabout half of the patients having no resolution to their complaints. Whilst an improvement was not achieved in all patients, as it was initially hypothesised, this procedure should be considered when a revision knee arthroplasty is performed with an unresurfaced patella.
PMCID: PMC3447165  PMID: 23002412
Anterior knee pain; bicondylar arthroplasty; revision knee arthroplasty; secondary patella resurfacing; unresurfaced patella.
17.  Blunt cerebrovascular trauma causing vertebral arteryd issection in combination with a laryngeal fracture: a case report 
The diagnosis and therapy of blunt cerebrovascular injuries has become a focus since improved imaging technology allows adequate description of the injury. Although it represents a rare injury the long-term complications can be fatal but mostly prevented by adequate treatment.
Case presentation
A 33-year-old Caucasian man fell down a 7-meter scarp after losing control of his quad bike in a remote area. Since endotracheal intubation was unsuccessfully attempted due to the severe cervical swelling as well as oral bleeding an emergency tracheotomy was performed on scene. He was hemodynamically unstable despite fluid resuscitation and intravenous therapy with vasopressors and was transported by a helicopter to our trauma center. He had a stable fracture of the arch of the seventh cervical vertebra and fractures of the transverse processes of C5-C7 with involvement of the lateral wall of the transverse foramen. An abort of the left vertebral artery signal at the first thoracic vertebrae with massive hemorrhage as well as a laryngeal fracture was also detected. Further imaging showed retrograde filling of the left vertebral artery at C5 distal of the described abort. After stabilization and reconfirmation of intracranial perfusion during the clinical course weaning was started. At the time of discharge, he was aware and was able to move all extremities.
We report a rare case of a patient with vertebral artery dissection in combination with a laryngeal fracture after blunt trauma. Thorough diagnostic and frequent reassessments are recommended. Most patients can be managed with conservative treatment.
PMCID: PMC3184109  PMID: 21843321
18.  Collagen type I hydrogel allows migration, proliferation and osteogenic differentiation of rat bone marrow stromal cells 
Hydrogels are potentially useful for many purposes in regenerative medicine including drug and growth factor delivery, as single scaffold for bone repair or as a filler of pores of another biomaterial in which host mesenchymal progenitor cells can migrate in and differentiate into matrix-producing osteoblasts. Collagen type I is of special interest as it is a very important and abundant natural matrix component. The purpose of this study was to investigate whether rat bone marrow stromal cells (rBMSCs) are able to adhere to, to survive, to proliferate and to migrate in collagen type I hydrogels and whether they can adopt an osteoblastic fate. rBMSCs were obtained from rat femora and plated on collagen type I hydrogels. Prior to harvest by day 7, 14, and 21, hydrogels were fluorescently labeled, cryo-cut and analyzed by fluorescent-based and laser scanning confocal microscopy to determine cell proliferation, migration, and viability. Osteogenic differentiation was determined by alkaline phosphatase activity. Collagen type I hydrogels allowed the attachment of rBMSCs to the hydrogel, their proliferation, and migration towards the inner part of the gel. rBMSCs started to differentiate into osteoblasts as determined by an increase in alkaline phosphatase activity after two weeks in culture. This study therefore suggests that collagen type I hydrogels could be useful for musculoskeletal regenerative therapies.
PMCID: PMC2891839  PMID: 20186733
Collagen type I hydrogel; bone marrow stromal cells; cell migration; osteogenic differentiation; bone regeneration

Results 1-18 (18)