Superior long-term survival for fixed bearing compared with mobile bearing in ligament-balanced total knee arthroplasty.

PURPOSE: Only few long-term data on ligament-balanced cruciate-retaining total knee arthroplasty (CR TKA) are currently available. Either a mobile- or fixed-bearing insert can be chosen, which showed good mid-term outcome and few complications and revisions. This multi-centre retrospective cross-sectional cohort study investigated the 12-year results of primary TKA using a balancing gap technique and compared survival and clinical outcome between fixed and mobile inserts. METHODS: In this retrospective cross-sectional cohort study, 557 cases of three clinics (2 Swiss, 1 Dutch) operated between 1998 and 2003 with the first series of a TKA implanted with a balanced gap technique (433 (77.7%) fixed, 124 (22.3%) mobile (anterior-posterior gliding (7-9 mm) and rotational (15°) degrees of freedom) inserts) were included for survival analysis (Kaplan-Meier, by insert type). At the 12-year follow-up (FU) examination of 189 cases, range of motion, knee society score (KSS), numeric rating scale (NRS) for pain and satisfaction were determined and radiographs were evaluated by median tests, by insert type. RESULTS: Of 521 cases available for analysis, 28 (5.4%; 11 fixed, 17 mobile bearing) were revised. Mean cumulative survival after 12.4 years was 97.0% (95% CI 94.7-98.4) for fixed bearings and 85.4% (95% CI 77.5-90.7) after 12.2 years for mobile bearings, p < 0.0001. Patients' mean age at 11.0 years FU (n = 189) was 78.0 (range 54.5-97.3) years. Mean total KSS was 157.8 (24-200) points, and mean passive flexion was 114° (45-150); no clinical score differed significantly between fixed and mobile bearings. CONCLUSION: This study showed a superior survival for fixed bearing compared with mobile bearing in a CR TKA using a ligament-balanced technique after more than 12 years. Clinical outcomes are excellent to good after long-term follow-up, and similar for fixed and mobile bearing. LEVEL OF EVIDENCE: Therapeutic studies-retrospective cohort study, Level III.

A simple method of measuring the wear of explanted acetabular component inserts.

AIMS: The determination of the volumetric polyethylene wear on explanted material requires complicated equipment, which is not available in many research institutions. Our aim in this study was to present and validate a method that only requires a set of polyetheretherketone balls and a laboratory balance to determine wear. METHODS: The insert to be measured was placed on a balance, and a ball of the appropriate diameter was inserted. The cavity remaining between the ball and insert caused by wear was filled with contrast medium and the weight of the contrast medium was recorded. The volume was calculated from the known density of the liquid. The precision, inter- and intraobserver reliability, were determined by four investigators on four days using nine inserts with specified wear (0.094 ml to 1.626 ml), and the intra-class correlation coefficient was calculated. The feasibility of using this method in routine clinical practice and the time required for measurement were tested on 84 explanted inserts by one investigator. RESULTS: In order to get the mean for all investigators and determinations, the deviation between the measured and specified wear was -0.08 ml (sd 0.12; -0.21 to 0.11). The interobserver reliability was 0.989 ml (95% confidence interval (CI) 0.964 to 0.997) and the intraobserver reliability was 0.941 for observer 1 (95% CI 0.846 to 0.985), 0.983 for observer 2 (95% CI 0.956 to 0.995), 0.939 for observer 3 (95% CI 0.855 to 0.984), and 0.934 for observer 4 (95% CI 0.790 to 0.984). The mean time required to examine the samples was two minutes (sd 2; 1 to 5). CONCLUSION: The method presented here was shown to be sufficiently precise for many settings and is a cost-effective and quick method of determining the volumetric wear of explanted acetabular components. However, the measurement of wear for scientific purposes will probably continue to involve more accurate and dedicated laboratory equipment.Cite this article: Bone Joint Res 2017;6:530-534.

Awareness and use of intertrochanteric osteotomies in current clinical practice. An international survey.

Current literature shows that intertrochanteric osteotomies can produce excellent results in selected hip disorders in specific groups of patients. However, it appears that this surgical option is considered an historical one that has no role to play in modern practice. In order to examine current awareness of and views on intertrochanteric osteotomies among international hip surgeons, an online survey was carried out. The survey consisted of a set of questions regarding current clinical practice and awareness of osteotomies. The second part of the survey consisted of five clinical cases and sought to elicit views on preoperative radiological investigations and preferred (surgical) treatments. The results of our survey showed that most of these experts believe that intertrochanteric osteotomies should still be performed in selected cases. Only 56% perform intertrochanteric osteotomies themselves and of those, only 11% perform more than five per year. The responses to the cases show that about 30-40% recommend intertrochanteric osteotomies in young symptomatic patients. This survey shows that the role of intertrochanteric osteotomies is declining in clinical practice.

Multi directional intertrochanteric osteotomy for primary and secondary osteoarthritis--results after 15 to 29 years.

Between 1974 and 1987, 276 intertrochanteric osteotomies were performed in 217 patients. In 48 hips the osteotomy was done for idiopathic osteoarthritis. In 166 hips the osteoarthritis was secondary to acetabular dysplasia, in 23 to trauma, in 14 to slipped capital femoral epiphysis, in five to Legg-Calvé-Perthes' disease and in 20 to avascular necrosis of the femoral head. Good results were achieved in young females with mild osteoarthritis secondary to acetabular dysplasia, and in patients with posttraumatic osteoarthritis. All other indications showed a poorer long-term survival. Our study shows that acetabular dysplasia and posttraumatic arthritis remain valid indications for intertrochanteric osteotomy.

Total hip replacement using hemi-circumferential interposition acetabuloplasty for acetabular deficiency in post-Perthes deformities: technique and long-term results.

We describe a technique of hemi-circumferential interposition grafting that allows placement of the cup in the anatomical position of the original acetabulum in the rare cases of post-Perthes or Perthes-like deformities of the femoral head combined with a steep and shallow acetabulum. This technique was performed on 10 hips (9 patients, with an average age of 56 years). One revision was performed for septic loosening after 2.1 years; however, the graft was well integrated and provided sufficient support for the revision cup. All the others had a good clinical and radiological result after an average of 11.4 years with an average Harris Hip Score of 97. The authors have found this an easy-to-use method, which can give an excellent, long-lasting result. It also provides important bone stock for possible subsequent revisions.;

Evaluation and treatment of young adults with femoro-acetabular impingement secondary to Perthes' disease.

Hip pain and loss of motion in young adults with previous Legg-Calve-Perthes-Disease may be caused by anterior femoro-acetabular impingement. Eleven patients (12 hips) with the chief complaint of groin pain and significant proximal femoral deformity were treated. Gadolinium-enhanced magnetic resonance arthrography in ten patients indicated labral injury and adjacent acetabular cartilage lesions in nine hips. A surgical dislocation of each hip confirmed that there was impingement induced intra-articular injury consistent with the pathology indicated on the MRI. Reshaping of the femoral head, with correction of the femoral head/neck offset, and treatment of the acetabular rim pathology was performed for each hip in conjunction with other procedures for the proximal femur. Correction of the impingement and increased range of motion could be visualized intra-operatively. At a mean follow-up of 33 months, half of all patients were pain-free and all had improvement in pain compared with preoperatively. Ten patients had an improved range of motion and two a slight decrease. No additional necrosis following the dislocation of the femoral head was seen.;

Entrapment of the external iliac vein in a both-column acetabular fracture.

We present a patient with an associated both-column acetabular fracture with entrapment of the external iliac vein in the fracture. This complication was not recognized until fracture manipulation during open reduction and fixation. This case report demonstrates that an acetabular fracture can have an associated vascular injury without any obvious clinical signs. This can be especially dangerous during percutaneous manipulation and fixation of these fractures as an obstruction or injury to the external iliac vein may occur and remain unrecognized. We feel that any surgeon involved in treating patients with acetabular or pelvic fractures should be aware of this potentially serious complication.

Acetabular reduction osteotomy using surgical dislocation of the hip joint for treatment of a malunited acetabular fracture.

INTRODUCTION: Acetabular fractures remain a challenge for the orthopedic and trauma surgeon, with frequently poor outcome in terms of pain and lack of motion and high rate of posttraumatic arthritis especially in badly reconstructed fractures where the anatomy was not restored. Surgical treatment of malunited acetabular fractures is often necessary, although it can be very complex. CASE PRESENTATION: We report a young woman who sustained both column fracture with central dislocation of the femoral head in which the posterior wall fragment was initially not fixed anatomically. CONCLUSIONS: Surgical dislocation of malunited acetabular fractures is a relatively new therapeutic option that provides full access to the femoral head and acetabulum without compromising the blood supply to the femoral head. Our results show that it can also be of great help in restoring malunited acetabular fractures.

Intertrochanteric osteotomy in young adults for sequelae of Legg-Calvé-Perthes' disease--a long term follow-up.

Between 1974 and 1999 we performed 15 intertrochanteric osteotomies in 14 patients with a painful hip secondary to Legg-Calvé-Perthes' disease. In seven patients, the osteotomy was combined with advancement of the greater trochanter, acetabular roof plasty, or both. One patient died 5 years after the osteotomy and one patient was lost to follow-up. One patient had a revision osteotomy 21 years after the initial osteotomy, and five patients had a prosthetic replacement 8-25 years after the osteotomy. The average follow-up of the remaining osteotomies was 11.3 years. An intertrochanteric osteotomy can decrease pain and improve clinical function medium and long term without radiological progression of joint degeneration.

Biomechanical and biological considerations relating to the clinical use of the Point Contact-Fixator--evaluation of the device handling test in the treatment of diaphyseal fractures of the radius and/or ulna.

The Point Contact-Fixator (PC-Fix) was designed as part of the developmental evolution of more biological devices for internal fixations. It is a device characterized by minimal contact to the underlying periosteum and bone, hereby minimizing potential damage to perfusion. A multicentre handling test was conducted in 1993 and 1994 in six hospitals to assess its performance. A total of 83 fractured forearm bones (34 radii and 49 ulnae) in 52 patients were stabilized with a PC-Fix. The mean age of the patients was 37 years. There were 24 AO type A, 24 type B and 5 type C fractures. Nine fractures were open. Mean follow-up was 15.6 months; follow-up was 100%. All 21 surgeons involved considered the use of the PC-Fix self-explanatory and relatively easy. Handling difficulties were mainly related to insertion of the monocortical screws. In particular, the precision required for insertion, the inability to incline the screw and the inability to pull the plate to the bone using the screw were considered hard to deal with. Stripping of the hexagonal slot was a problem at removal of the implant, possibly related to overtightening of the screws at insertion. In 76 of 83 bones (49 of 53 forearms), the fractures united without additional surgery. The healing pattern typically showed early callus formation bridging the fracture, followed by progressive mineralization of the central radiolucent line. Complications included one infection, one late displacement and four delayed unions, all requiring revision surgery. In 8 forearms, plate removal was performed after a mean of 10.3 months. Two refractures occurred after removal of the implant 6 and 7 months postoperatively. In conclusion, the practical handling of the new implant was straightforward and easily learnt. The treatment failures observed were related to technical and strategic errors. We consider that, when using devices with a locking compression principle, a minimum number of three screws should be placed on each side of the fracture, that interfragmentary compression of simple fractures is desirable in order to increase stability and that, contrary to in vivo animal studies, early plate removal is not indicated. The trend in fracture fixation is to improve the biomechanical and biological properties of operating technique and the devices used. The PC-Fix has proven a useful step in the right direction in this evolutionary process.

PC-Fix and local infection resistance--influence of implant design on postoperative infection development, clinical and experimental results.

Bacterial infection is still one of the main complications after internal fixation of fractures. The design of implants influences local infection resistance. To reduce the development of infections around implants after internal fixation, the vitality of the bone should be preserved to optimize cellular and humoral host defence mechanisms. For extramedullary fracture fixation, two implant designs are currently in routine use: the Dynamic Compression Plate (DCP) and the Limited Contact Dynamic Compression Plate (LC-DCP). The Point-Contact-Fixator (PC-Fix) is a new design concept based on the philosophy of the LC-DCP and the external fixator. Its function relies on splinting the fragments of a fracture internally with locking bolts rather than with screws that compress the plate to the bone. In this way, the blood supply is not compromised by compression of the periosteum. We investigated the effect of this new design on the incidence of postoperative infection rates in a clinical and an experimental setting. In a prospective multicentre study 1,229 PC-Fixators were used in 896 patients. Of these, 1,172 were available for assessment of infection development. The overall infection rate was 1.1% (13/1,172). The infection rate after open fractures was 1.6% (4/256) and after closed procedures (including closed fractures, osteotomies and non-unions) 1.0% (9/916). These rates are low in comparison to published rates using DCP and LC-DCP. In an experimental study, we compared the infection rates across two groups of rabbits four weeks after fixing either a bacterially contaminated DCP or a PC-Fix to the tibia. Infection rates in the DCP group were significantly higher than in the PC-Fix group: Of the 38 evaluated animals, 12 with a DCP and 5 with a PC-Fix developed local infection (p=0.022). The new PC-Fix design shows low postoperative infection rates in the clinical setting and lower infection rates than the DCP in the experimental setting. The design is an important step in the process of reducing postoperative infection rates.

[Treatment of united or malunited fractures of the elbow]. / Die Behandlung von nicht oder nicht korrekt verheilten Frakturen am Ellbogen.

Nonunions and malunions around the elbow are often due to incorrect initial treatment of a fracture. We have to differentiate between nonunions and malunion of adults and children. There are general principles for the treatment of nonunions and malunions of the distal humerus. They should not always be treated by decortication, internal fixation and bone graft. Removal of non-united fragments or a correction osteotomy may be good alternatives. A correct surgical approach and a biologically accurate osteosynthesis are necessary for good joint mobility, whereby the most difficult problem is to regain extension. An arthrolysis is not normally necessary during the first operation of a non- or malunion. It can be carried out, if necessary, on removal of implants. If these principles are followed, then the operation is usually successful and the patient satisfied. If treatment fails, the possibility of a joint replacement or an arthrodesis should not be forgotten.

Anterior femoroacetabular impingement after femoral neck fractures.

OBJECTIVES: To verify whether anterior femoroacetabular impingement can be a reason for hip pain and loss of motion in patients with a healed femoral neck fracture. DESIGN: Retrospective clinical, radiologic, and surgical evaluation. SETTING: Third referral hospital. PATIENTS: Nine patients who previously sustained a femoral neck fracture were treated between 1995 and 1999 for hip pain and loss of motion. All these mostly young patients (mean age 33.3 years) complained of groin pain. During the physical examination, acute pain could be elicited by passively forcing the femoral neck against the acetabular rim in flexion, adduction, and internal rotation, motions that were all limited. METHODS: Conventional radiographs and, if possible, arthrographic magnetic resonance imaging scans were followed by a surgical subluxation or dislocation of the femoral head to analyze the sequelae of anterior femoroacetabular impingement. Treatment was based on improvement of the anterior offset (the difference between the anterior contour of the head and the femoral neck) or intertrochanteric osteotomy to ameliorate clearance of the joint. RESULTS: Intraoperatively in eight patients (one not operated), impingement was found to result from insufficient reduction of the fracture, already visible on the conventional radiographs. Retrotorsion (mean 20 degrees) of the head caused anterior impingement in all patients, additional varus position (mean caput collum diaphysis angle 115 degrees) of the head caused anterolateral impingement in two patients. In all patients, anterior labral and adjacent acetabular cartilage lesions were found during surgical subluxation or dislocation of the femoral head, comparable to those seen on the magnetic resonance imaging scan. They proved to result from repetitive abutment and compression between the head-neck junction and the acetabulum. CONCLUSION: Femoroacetabular impingement can be a cause for hip pain and loss of motion in patients who previously sustained a femoral neck fracture. The condition causes degenerative anterior labral and adjacent acetabular cartilage lesions. Early treatment is essential to prevent further degeneration and osteoarthrosis of the joint. Prevention is predicated by initial precise anatomic reduction of such fractures in all planes.

Radiological signs of osteitis around extramedullary metal implants. A radiographic-microbiological correlative analysis in rabbit tibiae after local inoculation of Staphylococcus aureus.

Radiographic changes in the early stages of osteomyelitis may be subtle and, especially after plate osteosynthesis, frequently missed. A previously described experimental model of local bacterial infection was used in an attempt to determine the reliability of specific changes on conventional radiographs for the diagnosis of osteitis after metal-plate implantation and subsequent inoculation of Staphylococcus aureus in rabbit tibiae. Roentgenograms of the treated limbs were evaluated, and seven radiographic parameters, to which numerical scores were assigned, were determined for each bone. Our results substantiate the conclusion that a radiographically verified periosteal reaction is a constant and early skeletal feature of acute osteomyelitis and has the strongest association to the microbiological results (P < 0.05), emphasising its high predictive value. Plate implantation does not notably impede the diagnosis of osteomyelitis. An association between the amount of inoculated bacteria and the extent of radiographic changes could be found. The results of this present study closely resemble those described in man and suggest that this model may be useful for future experimental investigations in determining a score judging the severity of osseous involvement in local bacterial infection after plate osteosynthesis.

Influence of the design for fixation implants on local infection: experimental study of dynamic compression plates versus point contact fixators in rabbits.

OBJECTIVES: Comparison of infection resistance after local bacterial challenge associated with two different designs for fixation implants: the conventional dynamic compression plate (DCP) and the point contact fixator (PC-Fix). DESIGN: Randomized, prospective study in experimental animals. Grouped sequential experimental procedure. Observation time was twenty-eight days, with twenty animals per group. SETTING: Following surgery, animals were kept without restrictions in individual hutches. ANIMALS: Forty White New Zealand rabbits. Thirty-eight animals, nineteen per group, were included in the final evaluation. INTERVENTION: Under sterile conditions, specially manufactured titanium DCP or PC-Fix of identical dimensions were fixed to rabbit tibiae. After wound closure, different concentrations of Staphylococcus aureus, between 2 x 10(4) and 2 x 10(8) colony-forming units (CFU), were inoculated percutaneously at the implant site. MAIN OUTCOME MEASUREMENTS: Implants, underlying bone, and surrounding soft tissues were removed under sterile conditions and quantitatively evaluated for bacterial growth. Infection was defined as positive bacterial growth at the bone-implant interface. RESULTS: The overall infection rate was 45 percent. The infection dose of 50 percent (ID50) was 7.08 x 10(5) CFU for the DCP group and 8.51 x 10(6) CFU for the PC-Fix group. The infection rate was 63 percent (twelve of nineteen animals) for the DCP group and 26 percent (five of nineteen animals) for the PC-Fix group. This difference was statistically significant (p = 0.022). CONCLUSIONS: After local bacterial challenge, we found a statistically significant difference in the infection rates depending on the implant design. The higher infection resistance associated with the PC-Fix design seems to be related to the reduced contact area at the bone-implant interface.

Anterior femoroacetabular impingement after periacetabular osteotomy.

As experience with the Bernese periacetabular osteotomy has grown, an unexpected observation in a group of patients has alerted the authors to the risk of a secondary impingement syndrome that may occur some time after the periacetabular osteotomy. This possibly may explain residual pain and limited range of motion in a larger group of patients. The impingement is produced by abutment of the femoral head or head to neck junction on the anterior rim of the properly aligned acetabulum. The symptoms are those of restricted flexion, and limited or absent internal rotation in flexion, with variable groin pain. Magnetic resonance imaging studies may reveal acetabular labral disease and adjacent cartilage damage associated with the impingement. Lack of anterior or anterolateral offset between the femoral neck and head results in neck to rim contact when the hip is flexed and/or internally rotated. Before the periacetabular osteotomy this is compensated by the lack of anterior acetabular coverage, but after proper correction the mismatch becomes apparent. The authors recently have devised a routine during the periacetabular osteotomy procedure whereby after the acetabular fragment is corrected into the desired position, the joint is opened, visually inspected, and palpated for impingement with the hip flexed and internally rotated. When necessary, a resection osteoplasty of the femoral neck to head junction is performed to improve the head and neck offset and reduce the anterior contact. This, in the short term, has provided satisfactory prevention of postoperative impingement.

Infection after open reduction and internal fixation with dynamic compression plates--clinical and experimental data.

Infection rates for open reduction and internal fixation (ORIF) with the DCP in clinical studies are based on heterogeneous data on general risk factors and do not take into account the direct effect of the implant (material, design, surface, technique). The initial degree of bacterial contamination is generally unknown and the applied definition of the term infection is not mentioned. In our own prospective randomized clinical study including 281 cases of ORIF with the DCP (154 steel vs 127 titanium), the influence of the implant material on susceptibility to local infection was examined in relation to initial bacteria contamination (109 non-contaminated / 172 contaminated). Although in the group of contaminated DCPs the difference in the infection rates for stainless steel (sSt) and commercially pure titanium (cpTi) showed no statistical significance, a tendency was apparent. In an animal experiment, the lower rates of infection for c.p.Ti-DCP compared to sSt-DCP in the presence of a local bacterial challenge could be demonstrated with statistical significance. The need for further experimental research in the field of implant related local infection after ORIF will be discussed and strategies for further investigations proposed.