[Influence of timing of surgery on complication rates after cemented hemiarthroplasty for treatment of medial femoral neck fractures]. / Einfluss des Operationszeitpunktes auf die Komplikationsraten nach zementierter Hemiarthroplastik zur Behandlung medialer Schenkelhalsfrakturen.

BACKGROUND: The optimal timing of the implantation of a cemented hemiarthroplasty in the management of displaced medial femoral neck fractures is still the subject of current research. According to the current recommendations, these cases should be surgically treated within 24 h. The aim of this study was to evaluate the impact of the timing of surgery on operation-specific and nonspecific complications, intensive care treatment as well as mortality. MATERIAL AND METHODS: Overall, 152 cases were retrospectively investigated regarding several parameters (demographic data, comorbidities, surgery time, duration of hospital stay, intensive care treatment, general, bleeding, operation-specific and nonspecific complications). The statistical analysis was performed using the χ2-test and the unpaired Student's t­test as well as logistic regression analyses. RESULTS: A total of 152 patients were included and 71.1% of the operations were performed within 24 h and the remaining 28.9% after 24 h. All groups showed a similar profile of comorbidities. The analysis of the intensive care treatment showed no significant differences between the individual groups. The rate of postoperative pneumonia was moderately higher among the patients with a procedure after 24 h; however, with no severe courses. There were no significant differences regarding all other complications and the mortality rate between the individual time points of surgery. CONCLUSION: The present study demonstrated that patients operated on after 24 h showed no disadvantages regarding other complications, intensive care treatment or mortality, except from an increased postoperative pneumonia rate. These results could be taken into consideration for the next update of the treatment guidelines.

Positive Microbiological Findings at the Site of Presumed Aseptic Revision Arthroplasty Surgery of the Hip and Knee Joint: Is a Surgical Revision Always Necessary?

Little is known about patients that undergo presumed aseptic revision arthroplasty surgery of the hip and knee joint and having positive microbiological findings of the intraoperatively taken tissue samples. 228 "aseptic" operations were retrospectively analyzed from prospectively collected data with regard to the following parameters: demographic data; reasons for primary and revision surgery, respectively; time between primary and revision surgery; preoperative laboratory findings; microbiological and histopathological findings; type and length of systemic antibiotic therapy; clinical outcome; and follow-up. Identification of microorganisms was present in 8.8% of the cases (9.3% of the hip and 7.8% of the knee cases). Preoperatively, the median CRP value was 8.4 mg/l (normal values 0-5.0 mg/l) and the median WBC count 8,100 × 106/l (normal values 3, 700-10,100 × 106/l). The most common identified organism was methicillin-resistant Staphylococcus epidermidis in 30%, followed by viridans streptococci in 15% of the cases. In 7 cases, the microbiological findings were interpreted as a contamination, and no antibiotic therapy was administered. In the other cases, a systemic antibiotic therapy was applied for a time period between 2 weeks and 3 months. 68.4% of the patients did not have any infectious complications at a median follow-up of 20 (3-42) months. The present study indicates that more than 2/3 of the cases with positive microbiological findings at the site of presumed aseptic revision arthroplasty surgery of the hip and knee joint can be successfully treated conservatively and they do not require any further surgical therapy.

Partial two-stage exchange at the site of periprosthetic hip joint infections.

INTRODUCTION: In the past 10 years an increasing number of studies about partial two-stage exchange arthroplasty in the management of periprosthetic hip infections have been published. The aim of the present work was to systematically review the current knowledge about this procedure, and critically verify the success as well as the complications of this treatment option. MATERIALS-METHODS: A literature search was performed through PubMed until June 2018. Search terms were "partial two stage hip" and "partial retention hip", and "retaining well fixed hip". RESULTS: A total of 7 studies reporting on a total of 80 patients could be identified. All studies had a level of evidence IV. The great majority of the studies reported on the isolated removal of the acetabular cup and placement of an antibiotic-loaded cement spacer head onto the retained, well-fixed stem. Most of the periprosthetic infections were caused by staphylococci. The infection eradication rate varied between 81.3 and 100% at a mean follow-up between 19 and 70 months. Poor outcome was observed at the site of MRSA infections. CONCLUSIONS: The partial two-stage exchange arthroplasty appears to be a possible option in the management of PJI when one prosthetic component is well-fixed so that their removal might result in significant bone loss and compromise of fixation at the time of the later prosthesis reimplantation, and the causative organisms are not multiresistant. The small numbers published about this protocol does not allow for a generalization of application and should be only applied in highly selected patients. Future studies with larger collectives and longer follow-ups are welcome to evaluate the clinical success of this option and its possible role in the management of PJI.

An Untypical Case of Gouty Infiltration of Both Peroneal Tendons and a Longitudinal Lesion of the Peroneus Brevis Tendon Mimicking Synovial Sarcoma.

We present a case of a 70-year-old male patient with an untypical gout infiltration of the peroneal tendons mimicking synovial sarcoma. The patient had a negative history of gout at initial presentation in our department. Magnetic resonance imaging of the region revealed a finding highly suspicious for synovial sarcoma of the peroneal tendons. Open biopsy was performed. Histopathological examination of the tissue samples demonstrated the presence of gout with no signs of malignancy. The gout infiltration was excised in a subsequent surgery. Orthopedic surgeons should be aware of the potential manifestation of gout in tendons and bear this in mind in the differential diagnosis of soft tissue tumors.

Antibiotic Elution from Hip and Knee Acrylic Bone Cement Spacers: A Systematic Review.

Knowledge about the elution from antibiotic-loaded cement spacers is an indispensable premise for guarantee of clinical success. A systematic literature search was performed through PubMed. Search terms were "antibiotic elution" and "antibiotic release" in combination with "spacer," "hip spacer," and "knee spacer," respectively. A total of 11 studies could be identified. Seven studies reported on the release of antibiotics after spacer implantation, three studies at spacer removal, and one study on both time points. Seven studies reported on hip spacers, one study on knee spacers, and three studies on both. In eight studies, custom-made spacers have been implanted and in three prefabricated ones. In the majority of the studies, the cement has been loaded with an antibiotic combination, mostly consisting of aminoglycoside (either gentamicin or tobramycin) and vancomycin. Measured concentrations exceeded the minimal inhibitory concentration of the particular pathogen organisms in each case. However, large discrepancies were observed with regard to the height of the antibiotic concentration depending on the antibiotic combination and the antibiotic ratio used. Current literature data indicate a sufficient elution of antibiotics after spacer implantation and at spacer removal, respectively. Future studies are required to optimize the local antibiotic therapy at the site of spacer implantation.

Triple fracture during rehabilitation after revision total knee arthroplasty.

PURPOSE: The incidence of periprosthetic fractures after knee-joint implant revisions is increasing in prevalence. We present a method of treatment for a patient who sustained a triple fracture--a periprosthetic femur fracture, a patella fracture, and a tibial shaft fracture. METHODS: The femoral fracture was treated with a specially designed intramedullary nail, the patella fracture with a figure-of-eight suture, and the tibial shaft fracture by a minimal-invasive plate osteosynthesis using a percutaneous plating technique. RESULTS: Osseous consolidation was confirmed, and the patient presented a satisfying range of movement under full-weight-bearing conditions after mobilisation. CONCLUSIONS: Simultaneous multiple periprosthetic fractures are a special challenge, and in situ coupling of the endoprosthesis with a slotted hollow nail presents a valuable option for the treatment. LEVEL OF EVIDENCE: Level V, Expert opinion.

Pyrocarbon spacer as a trapezium replacement for arthritis of the trapeziometacarpal joint; a follow-up study of 60 cases.

Rhizarthrosis is the most common degenerative joint disease of the hand, affecting about 10% of the population. We report our results with trapezium replacement using a pyrocarbon spacer. Between January 2005 and April 2010, 70 patients underwent trapeziectomy with interposition of a pyrocarbon spacer. Sixty patients were examined at an average follow-up of 23.6 (5-64) months after the operation. Six (8.6%) of the 70 implanted pyrocarbon spacers dislocated. Based on the assessment scale devised by Buck-Gramcko, 19 patients achieved a very good outcome (31.6%), 31 patients (51.6%) had a good outcome, six results were satisfactory (10%) and four patients (6.6%) had a poor result. In this study, trapeziectomy and implantation of a pyrocarbon spacer achieved good or very good results in 83.2% of cases. The high cost of the implant and the observed rate of spacer dislocation should however be considered critically. While the short-term results of this method are encouraging, long-term outcomes will show whether this technique can keep up with the good results of suspension arthroplasty.

Enhancement of bone formation in hydroxyapatite implants by rhBMP-2 coating.

The combination of hydroxyapatite (HA) implants serving as osteoconductive scaffold with growth factors is an interesting approach for the improvement of bone defect healing. The purpose of this study was to test whether recombinant human bone morphogenetic protein-2 (rhBMP-2) coating of solid HA-implants improves bone formation in a cortical bone defect. Cylindrical trephine mill defects (diameter: 9.8 mm, depth: 10 mm) were created into the cortical tibia shaft of minipigs and subsequently filled either by plain HA cylinders (Endobon) or by rhBMP-2-coated HA cylinders. Fluorochrome labeling for the evaluation of time-dependent bone formation was done on days 8, 9, and 10 postsurgery with tetracyclin-100, at days 25 and 30 with alizarin-komplexon, and finally on days 32, 37, 73, and 79 with calcein green. Twelve weeks after implantation, the tibiae were harvested and were prepared for standard histological staining, fluorochrome analysis, and histomorphometry. Coating of HA implants with rhBMP-2 led to significant enhanced new bone formation of 84.7% (+/-4.6%) of the implant area with almost complete bony incorporation compared with only 27.7% (+/-8.5%) in the uncoated HA implants (p = 0.028). In both types of implants, osteoconduction of HA led to bone ingrowth of the surrounding host bone into the implants. However, only rhBMP-2-coated implants showed multitopic de novo bone formation reflecting the osteoinductive properties of rhBMP-2 in all areas of the HA implant. This study showed that the coating of HA ceramic implants with rhBMP-2 can significantly enhance new bone formation attributable to its osteoinductive effects.

Comparison of new bone formation, implant integration, and biocompatibility between RGD-hydroxyapatite and pure hydroxyapatite coating for cementless joint prostheses--an experimental study in rabbits.

This is the first work to report on additional Arginin-Glycin-Aspartat (RGD) coating on precoated hydroxyapatite (HA) surfaces regarding new bone formation, implant bone contact, and biocompatibility compared to pure HA coating and uncoated stainless K-wires. There were 39 rabbits in total with 6 animals for the RGD-HA and HA group for the 4 week time period and 9 animals for each of the 3 implant groups for the 12 week observation. A 2.0 K-wire either with RGD-HA or with pure HA coating or uncoated was placed into the intramedullary canal of the tibia. After 4 and 12 weeks, the tibiae were harvested and three different areas of the tibia were assessed for quantitative and qualitative histology for new bone formation, direct implant bone contact, and formation of multinucleated giant cells. Both RGD-HA and pure HA coating showed statistically higher new bone formation and implant bone contact after 12 weeks than the uncoated K-wire. There were no significant differences between the RGD-HA and the pure HA coating in new bone formation and direct implant bone contact after 4 and 12 weeks. The number of multinucleated giant did not differ significantly between the RGD-HA and HA group after both time points. Overall, no significant effects of an additional RGD coating on HA surfaces were detected in this model after 12 weeks.

[Bond strength of a bioresorbable bone adhesive: results of a biomechanical study in a sheep model]. / Biomechanische Analysen zur Verbundfestigkeit eines bioresorbierbaren Knochenklebers: experimentelle Untersuchungen am Schafsmodell.

The purpose of this study was to investigate the bond strength of a new bone adhesive based on ethylene glycol-oligolactide-bismethacrylate on 36 sheep. A 2-cm metaphysial segment was produced on the ulna of each sheep by an oscillating saw and it was not stabilized by any type of additional osteosynthesis. Adhesive was applied to the osteotomy gaps in 18 sheep, the remaining 18 animals served as controls. A total of 6 animals with glue and 6 controls were euthanized after 21, 42 and 84 days. The bond strength after repair of the gaps through bone adhesive compared to a control group was studied by using a four-point bending test. There was a continual increase of bending stiffness from 21 to 84 days in all sheep, with the highest bending stiffness of 102.83 N/mm2 by the glue group after 84 days as opposed to the control group with 58.48 N/mm2 (p = 0.25). Morphological investigations showed more callus formation by the control group than the adhesive group after 84 days (p = 0.04). In addition, an in vitro gluing of the ulna segment was performed with a four-point bending test after 10, 60 and 360 min polymerization time. The in vitro gluing of the ulna segment showed a continual increase of bending stiffness to 17.32 N/mm2 after 360 min (p = 0.59).

Elastic stable intramedullary nailing in pediatric femur and lower leg shaft fractures: intraoperative radiation load.

BACKGROUND: Elastic stable intramedullary nailing (ESIN) is currently the therapy of choice in unstable, transverse and short oblique femoral and tibial-fibular shaft fractures in childhood and adolescence. As with every intramedullary technique, it requires a greater intraoperative reliance on radiological imaging. Literature concerning intraoperative radiation load in ESIN is rare, results having a wide range from less than 1 minute to more than 15 minutes. METHODS: We performed a retrospective analysis of 53 femoral and 24 tibial shaft fractures. In addition, image intensifier times of several steps of the operative procedure in 10 femoral shaft fractures were evaluated prospectively. RESULTS: The average radiation time in femoral fractures was 70.3 (range, 12-193) seconds, in tibial shaft fractures, 42.4 (range, 16-108) seconds. The prospective analysis of femur shaft fractures was able to show the most intense use of imaging during fracture passage (43.2%) and placement of the nail tips (26.6%). Image intensifier times in educational operations were not significantly higher than in operations performed by experienced surgeons. CONCLUSIONS: The actual intraoperative radiation load is influenced by bone mass and soft tissue coverage. Surgeons are able to reduce it only by decreasing the fluoroscopy time. According to our results, image intensifier time should not exceed 3 minutes in ESIN of femoral shaft fractures and 2 minutes in ESIN of lower-leg fractures. Low intraoperative radiation times are a mark of quality with respect to the interests of patients, surgeons, and operation theater staff.

Treatment of a double nonunion of the femur by rhBMP-2.

A 49-year-old patient sustained an ipsilateral fracture of the lateral femoral neck and distal femoral shaft, which were treated with a long intramedullary nail with a hip screw component. Both fractures did not heal, and both nonunion sites were revised by reosteosynthesis with a dynamic hip screw for the femoral neck and a locked intramedullary nail for the shaft region combined with autogenous bone grafting at both sites. At 14 months from injury and after 2 operations, both nonunions persisted. At a third surgery, 1 kit of recombinant human bone morphogenetic protein-2 (rhBMP-2) on an absorbable collagen sponge was applied to each site, without any modification of the osteosynthesis or additional bone grafting. The lateral femoral neck and the femoral shaft consolidated 24 and 30 weeks, respectively, after the rhBMP-2 application, and the patient resumed his work as industrial worker after 7 months after his last surgery. We believe this is the first study to report the successful use of 2 kits of rhBMP-2 in a double nonunion of the femur.

Treatment of periprosthetic femoral fractures by effective lengthening of the prosthesis.

The increasing number of hip and knee arthroplasties implies a greater likelihood of periprosthetic fractures and need for successful treatment options. We asked whether in situ effective lengthening of the indwelling prosthesis by a custom-made slotted hollow intramedullary nail provided a reasonable alternative to the established internal fixation techniques and prosthesis exchange. Between 1994 and 2005, we treated 25 patients (four male and 21 female; average age, 80 years) with a hip or knee periprosthetic fracture using this technique. Preconditions included a well-fixed prosthesis with a conical tip. In 23 hip cases a retrograde femur nail and in two knee fracture cases an antegrade nail were used for in situ lengthening of a femoral hip or knee implant stem. In all 25 cases, we used a preoperatively manufactured custom-made implant; in 20 patients, we recommended immediate mobilization by partial or full weightbearing. Eighteen of 25 patients were followed a minimum of 7 months (mean, 25 months; range, 7-31 months). Three patients died and four were lost to followup. We observed fracture healing in all patients, but one female patient had subsequent prosthesis loosening. The major complication rate was 6% (one of 18). We believe effective lengthening of the indwelling prosthesis by a custom-made slotted hollow intramedullary nail is a reasonable option for treating periprosthetic femoral fractures.

The effects of combined gentamicin-hydroxyapatite coating for cementless joint prostheses on the reduction of infection rates in a rabbit infection prophylaxis model.

Infections remain a critical issue in total joint arthroplasty. Addition of antibiotics to bone cement was shown to significantly improve antimicrobial prophylaxis in cemented joint arthroplasty. In cementless joint arthroplasty a comparable prophylaxis by local antibiotics has not been possible yet. The aim of the current study was to investigate the antimicrobial effect of two different gentamicin-hydroxyapatite (HA) coatings for cementless prostheses in a rabbit infection model. Staphylococcus aureus with a dose of 10(7) CFUs was inoculated into the intramedullary canal of the tibia of 30 rabbits followed by the implantation of standard steel HA K-wires (n=10), steel K-wires coated with a gentamicin-HA combination (n=10), and steel K-wires coated with a gentamicin-RGD-HA combination (n=10), respectively. The animals were sacrificed after 28 days and clinical, histological and microbiological assessment on the bone and on the removed K-wire itself by agar plating and DNA-pulsed field gel electrophoresis were carried out to detect infection. There was a statistically significant reduction of infection rates by both gentamicin-coating types (0 infections in both groups) compared to standard HA coating (7 infections in 8 animals; 2 animals were lost due to acute diarrhea) (p<0.001). An excellent correlation between agar plating testing results of the K-wires and of the bone samples was found. Detailed histology showed cortical lysis, abscess and sequester formation in the infected animals. Both gentamicin-coating types showed significant improvement of infection prophylaxis compared to standard HA coating and, therefore, this coating technology could help to improve infection prophylaxis in cementless total joint arthroplasty. In further studies biocompatibility of the coatings has to be assessed.

Glycerol-l-lactide coating polymer leads to delay in bone ingrowth in hydroxyapatite implants.

Glycerol-l-lactide as coating polymer for the delivery of basic fibroblast growth factor (bFGF) from hydroxyapatite (HA) ceramic implants was shown to lead to significant delay in bone ingrowth into the implants compared to implants without the coating polymer. The purpose of this work was to study bone ingrowth in HA ceramic implants with and without the coating polymer but without growth factors to enable differentiation between a locking effect of the pores by the polymer and the fact of inactivation of the growth factors by the polymer, which could both be possible for the delay. A defect was created in the subchondral region of both femurs in 24 miniature-pigs and was either filled by the HA implants with or without the coating polymer. Histomorphometry showed a significant delay in bone ingrowth in the polymer coated implants both after 6 and 12 weeks. Detailed histology revealed that the HA pores were completely "locked" by the polymer leading to complete loss of the osteoconductive properties of the HA. Also electron microscopy showed filling of the HA pores by the polymer. Therefore, it can be concluded that glycerol-l-lactide should not be used to coat HA ceramic implants due to significant delay in bone ingrowth.

Frequency and effects of intratendinous and peritendinous calcifications after open Achilles tendon repair.

BACKGROUND: Although calcification of the Achilles tendon has been described by several authors, a detailed evaluation of its frequency and effects on clinical outcome has not been reported. The purposes of this work were to determine the frequency of calcifications in the Achilles tendon after open repair and their effects on clinical outcomes and to identify possible risk factors for postoperative calcification. METHODS: Thirty-six patients with open Achilles tendon repair were evaluated at an average followup of 19 months. Evaluation included a self-assessment questionnaire concerning treatment outcomes, clinical examination, and radiographic and ultrasonographic examinations. RESULTS: No patient had calcifications in the Achilles tendon area before surgery. Postoperatively, intratendinous or peritendinous calcifications, ranging in size from 3 mm to 37 mm, were found in 10 (28%) of the 36 patients. The development of calcifications was associated with chronic swelling, decreased range of motion of the ankle joint, and increase pain, especially with calcifications larger than 10 mm. No association was found between the development of calcifications and the surgical technique, suture materials, time from injury to surgery, or postoperative management, and no risk factors could be identified. CONCLUSIONS: Calcifications of the Achilles tendon appear to be frequent after open tendon repair and to have a negative effect on clinical outcome.

Effect of glycerol-L-lactide coating polymer on bone ingrowth of bFGF-coated hydroxyapatite implants.

Basic fibroblast growth factor (bFGF)-coated hydroxyapatite (HA) cylinders showed good bony incorporation in a previously conducted animal study. However, some cylinders exhibited focal inhomogeneous bone ingrowth. The purpose of the current study was to test whether glycerol-L-lactide polymer coating could improve release properties and bone incorporation of bFGF-coated HA implants. bFGF-coated HA cylinders with or without coating polymer were investigated for in vitro release of bFGF by an immuno-ligand-assay and also for bone ingrowth in miniature pigs after 42 and 84 days. Release from bFGF polymer composites was lower for the first 3 days compared to the other group but was more homogenous and detectable amounts were still found after 20 days. There was significant delay in bone ingrowth of the polymer implants in which even after 84 days bone ingrowth was not completed, whereas in the other group incorporation after 42 days occurred. Detailed histology revealed filling of the HA pores with the polymer, making ingrowth of the surrounding host bone impossible. Only after 84 days starting resorption of the polymer accompanied by bone ingrowth was found. The current study showed that glycerol-L-lactide is not suitable for coating of HA implants due to polymer induced "locking" of HA pores.

Bone ingrowth in bFGF-coated hydroxyapatite ceramic implants.

This experimental study was performed to evaluate angiogenesis, bone formation, and bone ingrowth in response to osteoinductive implants of bovine-derived hydroxyapatite (HA) ceramics either uncoated or coated with basic fibroblast growth factor (bFGF) in miniature pigs. A cylindrical bone defect was created in both femur condyles of 24 miniature pigs using a saline coated trephine. Sixteen of the 48 defects were filled with HA cylinders coated with 50 microg rhbFG, uncoated HA cylinders, and with autogenous transplants, respectively. Fluorochrome labelled histological analysis, histomorphometry, and scanning electron microscopy were performed to study angiogenesis, bone formation and bone ingrowth. Complete bone ingrowth into bFGF-coated HA implants and autografts was seen after 34 days compared to 80 days in the uncoated HA group. Active ring-shaped areas of fluorochrome labelled bone deposition with dynamic bone remodelling were found in all cylinders. New vessels could be found in all cylinders. Histomorphometric analysis showed no difference in bone ingrowth over time between autogenous transplants and bFGF-coated HA implants. The current experimental study revealed comparable results of bFGF-coated HA implants and autogenous grafts regarding angiogenesis, bone synthesis and bone ingrowth.

Reconstruction of the lower leg with the sural artery flap.

BACKGROUND: Soft tissue covering on the lower leg is frequently a difficult challenge and causes increasing problems for treatment in smaller hospitals. We introduce a plastic surgery method for covering these soft tissue defects. METHOD: An island of skin, centered above the sural nerve, is cut out in the middle dorsal area of the lower leg. The subcutaneous vascular pedicle is prepared along the nerve. The gained skin flap is rotated into the defect site and fixed without tension. The wound of the donor-site defect is usually closed primarily, and the flap pedicle is covered with Meshcraft. RESULTS: In 18 of the 21 patients treated by this method the flap healed without functional impairment, one patient experienced a necrosis leading to the loss of the flap. And a partial loss of the skin island was recorded in two cases, complete healing was achieved by means of Meshcraft transplantation. CONCLUSIONS: The superficial sural artery flap usually results in a reliable and complete healing of soft tissue defects within the area of the lower legs with justifiable operational expenditures also for elderly patients and those with vascular ailments.