Fracture-related infection: A consensus on definition from an international expert group.

Fracture-related infection (FRI) is a common and serious complication in trauma surgery. Accurately estimating the impact of this complication has been hampered by the lack of a clear definition. The absence of a working definition of FRI renders existing studies difficult to evaluate or compare. In order to address this issue, an expert group comprised of a number of scientific and medical organizations has been convened, with the support of the AO Foundation, in order to develop a consensus definition. The process that led to this proposed definition started with a systematic literature review, which revealed that the majority of randomized controlled trials in fracture care do not use a standardized definition of FRI. In response to this conclusion, an international survey on the need for and key components of a definition of FRI was distributed amongst all registered AOTrauma users. Approximately 90% of the more than 2000 surgeons who responded suggested that a definition of FRI is required. As a final step, a consensus meeting was held with an expert panel. The outcome of this process led to a consensus definition of FRI. Two levels of certainty around diagnostic features were defined. Criteria could be confirmatory (infection definitely present) or suggestive. Four confirmatory criteria were defined: Fistula, sinus or wound breakdown; Purulent drainage from the wound or presence of pus during surgery; Phenotypically indistinguishable pathogens identified by culture from at least two separate deep tissue/implant specimens; Presence of microorganisms in deep tissue taken during an operative intervention, as confirmed by histopathological examination. Furthermore, a list of suggestive criteria was defined. These require further investigations in order to look for confirmatory criteria. In the current paper, an overview is provided of the proposed definition and a rationale for each component and decision. The intention of establishing this definition of FRI was to offer clinicians the opportunity to standardize clinical reports and improve the quality of published literature. It is important to note that the proposed definition was not designed to guide treatment of FRI and should be validated by prospective data collection in the future.

Osteonecrosis of distal tibia in open dislocation fractures of the ankle.

INTRODUCTION: Open ankle dislocation fractures are one of the most severe injuries of the ankle. Development of posttraumatic arthrosis is well known. However, there are just a few case reports describing evidence of posttraumatic osteonecrosis (PON) of distal tibia. The pathophysiological mechanism remains unclear and the question of morphologic or personal risk factors cannot be answered. The goal of this study was to evaluate the morphologic characteristics of open dislocated ankle fractures in correlation with the development of PON to facilitate early identification of patients with higher risk of posttraumatic osteonecrosis. MATERIAL AND METHODS: In this study data from 28 patients with open dislocation fractures of the ankle between 1975 and 2006 found at our databases were evaluated retrospectively. For each patient we documented personal data, mechanism of injury, type of lateral malleolar fracture, severity of open fracture, degree of tibiotalar dislocation, presence of medial malleolar fracture, presence of deltoid ligament rupture, time until joint reduction and kind of surgical treatment. We also documented clinical complications and number of surgeries. Presence of PON was examined by radiographs, magnetic resonance imaging (MRI) or histological analysis. RESULTS: Within 12 out of 28 patients with open ankle dislocation fractures a PON of the distal tibia could be found. Nine out of 15 patients with high-energy trauma and 12 out of 19 patients with type C fibular fracture developed PON. 73% of male patients and 88% of the patients with type III soft tissue damage according to Gustillo developed PON. However, if patients suffered from type C fibular fracture, total talus dislocation and grade III soft tissue damage ("necrotic triad") PON was developed in 100% of cases. Other patient's characteristics like late joint reduction, postoperative infection or bimalleolar fracture showed no higher proportion of patients with PON. CONCLUSION: In this study we were able to identify clinical manifestations and risk factors for the development of PON of the distal tibia. All indentified risk factors were associated with heavy fracture mechanisms leading most likely to a serious devascularisation of at least parts of the distal tibial epiphysis. With regard to presented results early identification of patients with higher risk of PON might be possible and maybe additional treatment options can be initialised to protect patients from this process.

Long-term prognosis of nerve palsy after total hip arthroplasty: results of two-year-follow-ups and long-term results after a mean time of 8 years.

INTRODUCTION: Nerve damage is a rare but serious complication after THA. There exist only little data about the outcome of these patients particularly regarding the long-term results later than 2 years postoperatively. Aim of this study is to answer the following questions: Is the recovery to be expected for light nerve lesions different from the severe ones? Is there a possibility of nerve recovery more than 2 years after THA? Is the potential of nerve recovery depending on the affected nerve? MATERIALS AND METHODS: This study investigates 2,255 primary THA as well as revision surgeries performed from 1988 to 2003 relating to iatrogenic nerve lesion. We classified the nerve lesion according to the core muscle strength in severe (M0-M2) and light (M3-M4) nerve damage and differentiated between femoral, sciatic and superior gluteal nerve, according to the electromyography. RESULTS: We found 34 cases of iatrogenic nerve damage representing an incidence of 1.5 %. 17 of 34 (50 %) patients showed a complete recovery after 2 years. Out of the remaining 17 patients, six out of seven patients with a final examination after a median time of 93 months achieved further improvement. The different nerves showed no significant different potential of recovery. CONCLUSIONS: In contrast to the literature, an improvement beyond the limit of 2 years is probable and independent of the nerve affected.

The histology around the cemented Müller straight stem: A post-mortem analysis of eight well-fixed stems with a mean follow-up of 12.1 years.

The aim of this study was to obtain detailed long-term data on the cement-bone interface in patients with cemented stems, implanted using the constrained fixation technique. A total of eight stems were removed together with adjacent bone during post-mortem examinations of patients with well-functioning prostheses. Specimens were cut at four defined levels, contact radiographs were obtained for each level, and slices were prepared for histological analysis. Clinical data, clinical radiographs, contact radiographs and histological samples were examined for signs of loosening and remodelling. The mean radiological follow-up was 9.6 years and all stems were well-fixed, based on clinical and radiological criteria. Contact radiographs revealed an incomplete cement mantle but a complete filling of the medullary canal for all implants. Various amounts of polyethylene particles were evident at the cement-bone interface of seven stems, with no accompanying inflammatory reaction. Cortical atrophy and the formation of an 'inner cortex' were confirmed in six of eight stems by contact radiographs and histology, but were only visible on two clinical radiographs. Our results confirm that a complete cement mantle is not essential for the survival of Müller straight stems into the mid term, and support our hypothesis that no benefit to long-term survival can be expected from modern cementing techniques.

Fixation and loosening of the cemented Muller straight stem: a long-term clinical and radiological review.

The original forged Müller straight stem (CoNiCr) has shown excellent ten- to 15-year results. We undertook a long-term survival analysis with special emphasis on radiological changes within a 20-year period of follow-up. In all, 165 primary total hip replacements, undertaken between July 1984 and June 1987 were followed prospectively. Clinical follow-up included a standardised clinical examination, and radiological assessment was based on a standardised anteroposterior radiograph of the pelvis, which was studied for the presence of osteolysis, debonding and cortical atrophy. Survival of the stem with revision for any reason was 81% (95% confidence interval (CI), 76 to 86) at 20 years and for aseptic loosening 87% (95% CI, 82 to 90). At the 20-year follow-up, 15 of the surviving 36 stems showed no radiological changes. Debonding (p = 0.005), osteolysis (p = 0.003) and linear polyethylene wear (p = 0.016) were associated with aseptic loosening, whereas cortical atrophy was not associated with failure (p = 0.008). The 20-year results of the Müller straight stem are comparable to those of other successful cemented systems with similar follow-up. Radiological changes are frequently observed, but with a low incidence of progression, and rarely result in revision. Cortical atrophy appears to be an effect of ageing and not a sign of loosening of the femoral component.

Backside volumetric change in the polyethylene of uncemented acetabular components.

Polyethylene wear of acetabular components is a key factor in the development of periprosthetic osteolysis and wear at the articular surface has been well documented and quantified, but fewer data are available about changes which occur at the backside of the liner. At revision surgery for loosening of the femoral component we retrieved 35 conventional modular acetabular liners of the same design. Linear and volumetric articular wear, backside volumetric change and the volume of the screw-head indentations were quantified. These volumes, clinical data and the results from radiological Ein Bild Röntgen Analyse migration analysis were used to identify potential factors influencing the volumetric articular wear and backside volumetric change. The rate of backside volumetric change was found to be 2.8% of the rate of volumetric articular wear and decreased with increasing liner size. Migrated acetabular components showed significantly higher rates of backside volumetric change plus screw-head indentations than those without migration. The backside volumetric change was at least ten times larger than finite-element simulation had suggested. In a stable acetabular component with well-anchored screws, the amount of backside wear should not cause clinical problems. Impingement of the screw-heads could produce more wear particles than those generated at the liner-shell interface. Because the rate of backside volumetric change is only 2.8% of the rate of volumetric articular wear and since creep is likely to contribute a significant portion to this, the debris generated by wear at the backside of the liner may not be sufficient to create a strong osteolytic response.

Postoperative rehabilitation after percutaneous Achilles tendon repair: early functional therapy versus cast immobilization.

PURPOSE: To report a comparative study on postoperative management following percutaneous repair of acute Achilles tendon ruptures. METHODS: One hundred and three patients with percutaneous repair after acute Achilles tendon rupture were prospectively entered in our departmental database. Before July 1999, 15 patients were treated postoperatively with below-knee cast immobilization; after July 1999, patients underwent early functional therapy using a special shoe. Patients were seen at 6 weeks, 12 weeks, and 12 months after surgery. Matched pairs were selected based upon gender, age, weight, height, body mass index, and the side involved. The total number of patients consisted of 14 matched pairs. Compared outcomes included clinical evaluation, time away from work, and time before return to sports. RESULTS: Fifteen patients had an objective force reduction compared to the nonoperated side (9 cast group; 6 shoe group). The mean Achilles tendon score was 81 points in the cast group and 88 points in the shoe group. Patients in the cast group had a significantly (p = 0.042) longer time before return to work (67 days) compared to those in the shoe group (37 days). CONCLUSION: Early mobilization in a special shoe is preferable to postoperative immobilization after percutaneous Achilles tendon repair. It provides a good clinical outcome and shortens the time for return to work and sports.

Ex vivo adenoviral transfer of bone morphogenetic protein 12 (BMP-12) cDNA improves Achilles tendon healing in a rat model.

The aim of our study was to evaluate the histological and biomechanical effects of BMP-12 gene transfer on the healing of rat Achilles tendons using a new approach employing a genetically modified muscle flap. Biopsies of autologous skeletal muscle were transduced with a type-five, first-generation adenovirus carrying the human BMP-12 cDNA (Ad.BMP-12) and surgically implanted around experimentally transected Achilles tendons in a rat model. The effect of gene transfer on healing was evaluated by mechanical and histological testing after 1, 2, 4 and 8 weeks. One week after surgery, the maximum failure load of the healing tendons was significantly increased in the BMP-12 group, compared with the controls, and the tendon stiffness was significantly higher at 1, 2 and 4 weeks. Moreover, the size of the rupture callus was increased in the presence of BMP-12 and there was evidence of accelerated remodeling of the lesion in response to BMP-12. Histological examination showed a much more organized and homogeneous pattern of collagen fibers at all time points in lesions treated with the BMP-12 cDNA muscle graft. Both single fibrils and the collagen fibers had a greater diameter, with a higher degree of collagen crimp than the collagen of the control groups. This was confirmed by sirius red staining in conjunction with polarized light microscopy, which showed a higher shift of small yellow-green fibers to strong yellow-orange fibers after 2, 4 and 8 weeks in the presence of BMP-12 cDNA. There was also an earlier shift from fibroblasts to fibrocytes within the healing tendon, with less fat cells present in the tendons of the BMP-12 group compared with the controls. Treatment with BMP-12 cDNA-transduced muscle grafts thus produced a promising acceleration and improvement of tendon healing, particularly influencing early tissue regeneration, leading to quicker recovery and improved biomechanical properties of the Achilles tendon. Further development of this approach could have clinical applications.

[Corrective osteotomy of post-traumatic malunions and pseudarthroses in the femur using a fork plate: a prospective analysis of 23 consecutive cases]. / Korrekturosteotomien von posttraumatischen Fehlstellungen und Pseudarthrosen im Bereich des Femurs mittels Gabelplatte: Eine prospektive Analyse von 23 konsekutiven Fällen.

INTRODUCTION: The fork plate is a further development of the AO fixed-angle blade plate, which facilitates the seeding of the angle blade. In a prospective study we evaluated the applicability of the fork plate for the correction of post-traumatic malunions and pseudarthroses in the femur. MATERIAL AND METHODS: Between 01/1993 and 12/2003 a consecutive series of 23 patients were operated due to post-traumatic malunion or pseudarthrosis of the femur with an average age of 46 years at the time of surgery. The operative procedure is analogous to the one using angle blade plates. The most important surgical step, the placement of the fork instead of the blade, is more precise thanks to stepwise control with the image intensifier. RESULTS: All preexisting malunions and pseudarthroses were corrected with the fork plate as preoperatively planned. Complications not related to the implant were found in 13%, all of which resolved without sequelae. In 87% we found a bony union of the osteotomy after 3 months, and the three remaining femora healed within an additional 2-12 months without loss of the correction achieved. CONCLUSION: In all of the cases analyzed, the fork plate proved to be of value for correction of femoral malunion and pseudarthrosis. In relation to the angle blade plate, the fork plate features a modified surgical technique with the same possible indications. As a consequence this modification provides a high level of therapeutic safety even with a small number of annual operations performed.

[Infected knee arthroplasty. A treatment algorithm at the Kantonsspital Liestal, Switzerland]. / Infekt nach Knietotalprothesenimplantation. Zweizeitiger Wechsel als Element des Liestaler Behandlungsalgorithmus.

The algorithm differentiates between several surgical treatment options depending on the duration of the infection, on the amount of soft tissue damage, on the stability of the implant and the type of micro-organism. If the symptoms of infection exist for less then 3 weeks, a radical debridement is indicated under the condition of a stable implant and good soft tissue conditions. A one-stage exchange is possible with satisfactory conditions of soft tissue and the absence of difficult-to-treat, resistant micro-organisms. In patients with sinustracts or compromised soft tissue, a two-stage exchange is necessary. The placement of a spacer combined with a short interval of 2-3 weeks until reimplantation is possible for easy-to-treat bacteria. For difficult-to-treat micro-organisms, an interval of 8 weeks without spacer until reimplantation is necessary. While stabilised by a fixateur extern, antimicrobial treatment is administered for the first 6 weeks. If the tissue specimens at reimplantation two weeks later do not show growth of bacteria or signs of acute inflammation, antimicrobial treatment can be discontinued. For all other above-mentioned treatment protocols, we administer antimicrobial treatment for a total of 6 months. We present the results of 40 consecutive infected total knee arthroplasties treated according to our algorithm, including a detailed presentation of the two-stage revision procedure.

Outcome of prosthetic knee-associated infection: evaluation of 40 consecutive episodes at a single centre.

Few studies have compared the long-term success of different surgical strategies in prosthetic knee-associated infection. Accordingly, a retrospective cohort study was performed of 40 episodes in 35 consecutive patients undergoing revision surgery for prosthetic knee-associated infection at a single centre between 1988 and 2003. The median patient age was 70 (44-90) years; the median follow-up period was 28 (2-193) months; 45% of infections were early, 23% were delayed, and 32% were late; and 55% of infections were caused by staphylococci. The probability of survival without prosthesis failure was 92.4% (95% CI, 84.1-100) after 1 year, and 88.7% (95% CI, 78-99.4) after 2 years. Recurrence-free survival was observed in 20 (95%) of 21 patients treated with debridement and retention, in both patients with one-stage exchange, and in 11 (85%) of 13 patients with two-stage exchange. Patients with delayed infection had a worse outcome than those with early or late infection (67% vs. 97%; p < 0.03). Patients with at least partially adequate antimicrobial therapy had a higher success rate than those with inadequate treatment (94% vs. 60%; p 0.069). The outcome was similar for patients with a duration of therapy of 3 to < 6 months, and those with a duration of therapy of > or = 6 months (91% vs. 87% success). Different surgical procedures had similar success rates, provided that the type of infection, the pathogen, the stability of the implant and the local skin and soft-tissue condition were considered. Adherence to an algorithm defining a rational surgical and antibiotic treatment strategy contributed to a favourable outcome.

Functional ankle control of rock climbers.

OBJECTIVE: To evaluate whether rock climbing type exercise would be of value in rehabilitating ankle injuries to improve ankle stability and coordination. [figure: see text] METHODS: A group of 25 rock climbers was compared with a group of 26 soccer players. All were male, uninjured, and exercised three to four times a week. Active ankle stability was evaluated by one leg stand stabilometry (measurement of migration of the centre of gravity) and measurements of maximum strength of ankle isokinetic concentric flexion and extension (Cybex). RESULTS: The rock climbers showed significantly better results in the stabilometry and greater absolute and relative maximum strength of flexion in the ankle. The soccer players showed greater absolute but not relative strength in extension. CONCLUSION: Rock climbing, because of its slow and controlled near static movements, may be of value in the treatment of functional ankle instability. However, it has still to be confirmed whether it is superior to the usual rehabilitation exercises such as use of the wobble board.

Five-year results of two cemented hip stem models each made of two different alloys.

INTRODUCTION: The aim of this study was to compare the influence of two different cemented hip stems each made of two different alloys concerning survival and outcome. MATERIALS AND METHODS: The 5-year results with 161 Mueller straight stems made of cobalt chromium (SS CoCr), 272 Mueller straight stems made of titanium (SS Ti), 233 Mueller SL stems made of titanium (SL Ti) and 255 SL stems made of cobalt chromium (SL CoCr) implanted consecutively in this order were compared. All patients were followed up prospectively during the first 5 years after implantation. The evaluation of the results was retrospective. RESULTS: The survival rates for aseptic loosening were 100% (SS CoCr), 92.8% (SS Ti), 81.6% (SL Ti) and 97.8% (SL CoCr). Clinical and radiological outcomes like pain occurrence, use of pain medication, ability to climb stairs, amount of stem subsidence and osteolysis correlated statistically significantly with the results of the survival rates. Concerning the two alloys, chromium cobalt showed better results, and concerning the two designs, the straight stem had a better outcome. For the four prostheses being compared, the results were influenced more by the alloy than by the design, and the small-sized titanium stems were more susceptible to undergoing revision than the large-sized prostheses. CONCLUSION: Stem design and even more alloy may influence the survival rate and clinical outcome. Evaluating the results, we recommend the use of the classic straight stem prosthesis made of cobalt chromium.

Management of infection associated with total hip arthroplasty according to a treatment algorithm.

BACKGROUND: An algorithm for the management of hip arthroplasty-associated infections was validated in a cohort study. PATIENTS: 60 patients with 63 episodes of total hip arthroplasty-associated infections observed from 1985 to 2001 were included. The treatment algorithm was based on the time of manifestation, pathogenesis, and condition of implant and soft tissue. Three treatment options were proposed, namely debridement with retention, one-stage and two-stage replacement. RESULTS: The median patients' age was 72 years, the median follow-up 28 months; 29% were early, 41% delayed, and 30% late infections, 57% of the infections were exogenously and 43% hematogenously acquired. The overall success rate for the first treatment attempt was 83% (52/63). Patients treated according to the algorithm had a better outcome than the others (44/50 = 88% vs 8/13 = 62%, Relative risk (RR) 0.31, 95% confidence interval (CI): 0.11-0.86, p < 0.03); those treated with adequate antimicrobial therapy had a better success rate (87% vs. 50%, p < 0.01). CONCLUSION: The proposed algorithm defines a rational surgical/antibiotic treatment strategy.

Ten-year follow-up of primary straight-stem prosthesis (MEM) made of titanium or cobalt chromium alloy.

INTRODUCTION: An increased revision rate of cemented titanium stems compared with cobalt chromium stems has been described after a short follow-up. In this paper, the minimum 10-year outcome after the implantation of titanium (Ti) and cobalt chromium ME (CoCr) Mueller straight-stem prostheses is analyzed in order to estimate the prognosis of the patients who were not revised. MATERIALS AND METHODS: . A total of 272 (Ti) straight stems were implanted between 1987 and 1990, and 161 (CoCr) straight stems were implanted from 1984 to 1987. Clinical and radiological checks were carried out prospectively after 1, 2, 5, and 10 years. RESULTS: The survival rate concerning aseptic loosening of the stem after 5 years was 92.8% (Ti)/100% (CoCr) and after 10 years 80.9%/98.2%. Thirty-six (Ti)/2 (CoCr) patients required revision of the stem due to aseptic loosening. The revision rate per year of the Ti stems increased until 7 years postoperatively and decreased thereafter. At the 10-year follow-up, 107 Ti and 84 CoCr implants were checked, and the subjective and clinical parameters did not differ between the two groups. CONCLUSION: Except for an increased subsidence rate of the stems in the Ti (31%) versus the CoCr group (16%), there was no statistically significant difference in the clinical and radiological outcomes.

Management of infection associated with prosthetic joints.

In orthopedic implant surgery, infection is rare, but difficult to eradicate. Neither diagnosis nor treatment of such infections is standardized. A MEDLINE search with the keywords "orthopedic implant-related infection" and "joint replacement and infection" identified studies published from 1982-2002. One single randomized controlled trial could be found. In addition, larger retrospective case series and observational studies with clear definition of the observed intervention were also selected for inclusion. A rational algorithm based on clinical experience in orthopedic implant-related infections, observational studies and the controlled trial is presented. The conditions for the different therapeutic options (debridement with retention, one-stage exchange, two-stage exchange, removal without reimplantation or suppressive antibiotic treatment) are presented. The proposed algorithm is based on the interval after implantation (early, delayed, late), the type of infection (exogenous vs hematogenous), the condition of the implant and the soft tissue, as well as comorbidity of the patient. Considering both surgical and antimicrobial therapy, our algorithm facilitates either retrospective evaluation of case series or the planning of well-defined prospective studies.

Friction between human finger flexor tendons and pulleys at high loads.

A method was developed to indirectly measure friction between the flexor tendons and pulleys of the middle and ring finger in vivo. An isokinetic movement device to determine maximum force of wrist flexion, interphalangeal joint flexion (rolling in and out) and isolated proximal interphalangeal (PIP) joint flexion was built. Eccentric and concentric maximum force of these three different movements where gliding of the flexor tendon sheath was involved differently (least in wrist flexion) was measured and compared. Fifty-one hands in 26 male subjects were evaluated. The greatest difference between eccentric and concentric maximum force (29.9%) was found in flexion of the PIP joint. Differences in the rolling in and out movement (26.8%) and in wrist flexion (14.5%) were significantly smaller. The force of friction between flexor tendons and pulleys can be determined by the greater difference between eccentric and concentric maximum force provided by the same muscles in overcoming an external force during flexion of the interphalangeal joints and suggests the presence of a non-muscular force, such as friction. It constitutes of 9% of the eccentric flexion force in the PIP joint and therefore questions the low friction hypothesis at high loads.

Revision cup arthroplasty using Burch-Schneider anti-protrusio cage.

From 1986 until 1995 we used the Burch-Schneider anti-protrusio cage in 31 patients (33 hips) and followed the patients for 5 years. Five patients died within the 5-year follow-up. Clinical outcome listed an average Harris hip score of 71/70/66 points after 1, 2 and 5 years respectively. One patient had a revision due to late-onset haematogenous infection. We found cup migration in nine patients. Migration was self-limiting in three cases and in two there was no bony graft ingrowth. Screw breakage was seen in one case. All migrated cages showed a higher rotational centre than cages without migration.

Statistical analysis of failure times in total joint replacement.

Time to revision is an important criterion describing the quality of implants in total joint surgery. Estimates of failure probabilities are required to inform a patient about the risk of suffering a reoperation. Also, regression models are used for comparing different prosthesis designs. Typically, patients dying before a revision are considered as censored for time to prosthesis failure. We argue that this technique is inadequate for estimation of failure probabilities and insufficient for comparison of different designs. We propose a new approach based on a competing risk model to account for concurrent mortality. We describe differences in the estimation of failure probabilities and in the interpretation of regression models for implant failure. Additionally, we introduce a random effects term in the regression model to account for potential dependencies in the failure times of bilaterally treated patients. The new approach is illustrated with fictitious data and data from an observational study conducted at a specialized hospital in Switzerland.