Kevin J. Mulhall

Current etiologies and modes of failure in total knee arthroplasty revision.

Although total knee arthroplasty is a very effective intervention and increasing in prevalence, failures do occur. We studied patients presenting for total knee arthroplasty revision to determine any modifiable causes of failure, both short and long term, and where future efforts should be directed to reduce the incidence of failure. A multicenter prospective observational cohort study of 318 consecutive patients, with minimum 1 year follow-up, undergoing total knee arthroplasty revision was performed. Associations between modes of failure were also assessed. The mean time from primary procedure to total knee arthroplasty revision was 7.9 years. Many patients (64.4%) had more than one cause of failure. Thirty-one percent of patients were early (< 2 years) failures at a mean of 11 months. These had a higher prevalence of infection, perioperative factors and comorbidities. Late failures occurred at a mean of 119.2 months. Other major causes of failure included instability (28.9%), wear (24.5%) and component loosening suggesting the importance of modifications in technique, implants and other areas. Application of these findings will ultimately reduce revision numbers through continued refinement of total knee arthroplasty practice and through further specific investigation of these modes of failure.Level of Evidence: Therapeutic study, level II-2 (prospective study). See the Guidelines for Authors for a complete description of levels of evidence.

Adhesion of Staphylococcus to orthopaedic metals, an in vivo study

This study describes a new model of biofilm study in rabbits. The primary focus of this study was to assess biofilm adhesion to orthopaedic metals in their first 48 h in a femoral intramedullary implantation model. Two previous inoculation methods i.e. that of pre‐ and direct inoculation were studied with two bacterial isolates namely Staphylococcus aureus and epidermidis, on titanium and stainless steel metallic implants. A method of sonication and log dilution/plating was used to assess biofilm bacteria adhering to implants. Silver coated metals were then compared with their respective control metals in the new model.

Femoroacetabular impingement after slipped capital femoral epiphysis: does slip severity predict clinical symptoms?

Background Femoroacetabular impingement (FAI) may be common after slipped capital femoral epiphysis though the actual frequency is unknown. The purpose of this study was to determine the frequency of symptomatic FAI in young adults after slipped capital femoral epiphysis and define its relationship with slip severity. Methods We retrospectively reviewed a consecutive series of 49 patients (65 hips) to determine patient and slip characteristics and treatments. Patients were then recalled for clinical and radiographic review to assess symptoms, particularly impingement, and outcomes after skeletal maturity. Results Thirty-six patients (49 hips) were reviewed clinically and radiographically with a mean follow-up of 6.1 years (range: 2.2 to 13.1 y). All patients had reached skeletal maturity. Thirty-one percent (15/49) of patients complained of hip pain or stiffness, whereas 32% (16/49) had clinical signs of impingement. The Southwick slip angle and grade of slip or Loders classification of physeal stability were not predictive of impingement at follow-up. The anterior head-neck offset angle (α angle) correlated most strongly with FAI (r=0.26). No pre-slips or prophylactically pinned hips developed clinical impingement in this review. Conclusions In the absence of radiographic indicators to predict FAI, we advocate all but those hips pinned prophylactically or for pre-slip should be followed into adulthood and clinically monitored for impingement. Grade of slip in adolescence cannot be used as a predictive tool for FAI later in life. Level of Evidence Level II, retrospective study.

Total hip replacement in patients with neurological conditions

Neurological conditions affecting the hip pose a considerable challenge in replacement surgery since poor and imbalanced muscle tone predisposes to dislocation and loosening. Consequently, total hip replacement (THR) is rarely performed in such patients. In a systematic review of the literature concerning THR in neurological conditions, we found only 13 studies which described the outcome. We have reviewed the evidence and discussed the technical challenges of this procedure in patients with cerebral palsy, Parkinsons disease, poliomyelitis and following a cerebrovascular accident, spinal injury or development of a Charcot joint. Contrary to traditional perceptions, THR can give a good outcome in these often severely disabled patients.

Controlled release of transforming growth factor-β3 from cartilage-extra-cellular-matrix-derived scaffolds to promote chondrogenesis of human-joint-tissue-derived stem cells.

The objective of this study was to develop a scaffold derived from cartilaginous extracellular matrix (ECM) that could be used as a growth factor delivery system to promote chondrogenesis of stem cells. Dehydrothermal crosslinked scaffolds were fabricated using a slurry of homogenized porcine articular cartilage, which was then seeded with human infrapatellar-fat-pad-derived stem cells (FPSCs). It was found that these ECM-derived scaffolds promoted superior chondrogenesis of FPSCs when the constructs were additionally stimulated with transforming growth factor (TGF)-β3. Cell-mediated contraction of the scaffold was observed, which could be limited by the additional use of 1-ethyl-3-3dimethyl aminopropyl carbodiimide (EDAC) crosslinking without suppressing cartilage-specific matrix accumulation within the construct. To further validate the utility of the ECM-derived scaffold, we next compared its chondro-permissive properties to a biomimetic collagen-hyaluronic acid (HA) scaffold optimized for cartilage tissue engineering (TE) applications. The cartilage-ECM-derived scaffold supported at least comparable chondrogenesis to the collagen-HA scaffold, underwent less contraction and retained a greater proportion of synthesized sulfated glycosaminoglycans. Having developed a promising scaffold for TE, with superior chondrogenesis observed in the presence of exogenously supplied TGF-β3, the final phase of the study explored whether this scaffold could be used as a TGF-β3 delivery system to promote chondrogenesis of FPSCs. It was found that the majority of TGF-β3 that was loaded onto the scaffold was released in a controlled manner over the first 10days of culture, with comparable long-term chondrogenesis observed in these TGF-β3-loaded constructs compared to scaffolds where the TGF-β3 was continuously added to the media. The results of this study support the use of cartilage-ECM-derived scaffolds as a growth factor delivery system for use in articular cartilage regeneration.

Socioeconomic issues and demographics of total knee arthroplasty revision

Despite rising numbers of total knee arthroplasty revision (TKAR) procedures there remains a paucity of information regarding the relationships between total knee arthroplasty failure and socioeconomic and educational status, demographics, general health and functional disability. We performed a multicenter prospective study of 290 consecutive TKAR patients in order to determine whether they differed from the population they were drawn from in terms of socioeconomic or educational status, race or gender. Secondary aims were to establish the relative comorbid status of this population, social supports and their general health status compared to national norms and their modes of failure. Our cohort consisted of 137 males and 153 females with a mean age of 68.6 years (range, 34-85 years), substantial overall functional disability according to the SF-36 and a large average number of comorbidities at baseline. We found a relative overrepresentation of patients of comparatively low socioeconomic and educational status and also of Caucasian patients in the TKAR population. This large prospective investigation demonstrates demographic features associated with TKA failure and provides a platform for further investigations on the effect demographic characteristics have on the outcomes of TKAR.Level of Evidence: Prognostic Study, Level II (Lesser quality prospective study). See Guidelines for Authors for a complete description of the Levels of Evidence.

Radiographic prediction of intraoperative bone loss in knee arthroplasty revision.

A key challenge for orthopaedic surgeons performing revision total knee arthroplasty is the management of bone loss. The goal of our study was to test the validity of predicting bone loss from preoperative radiographs using two commonly utilized bone loss assessments: the Anderson Orthopaedic Research Institute and University of Pennsylvania systems and secondarily to assess the frequency and severity of bone loss in a prospective study of total knee arthroplasty revisions. Ninety-eight total knee arthroplasty revision patients were assessed and bone loss was detected in 76 (77.6%) patients preoperatively and intraoperatively. The validity of both systems was established. Agreement between preoperative and intraoperative Anderson Orthopaedic Research Institute classification was fair for the femur and good for the tibia. All University of Pennsylvania preoperative measures were correlated with intraoperative measures. Establishing valid and reliable preoperative systems of measuring bone loss facilitates planning of total knee arthroplasty revision and rehabilitation and meaningful comparisons between different series of patients and treatment protocols.Level of Evidence: Diagnostic study, level I (prospective testing of previously developed diagnostic criteria on consecutive patients [with universally applied reference “gold” standard]). See Author Guidelines for a complete description of levels of evidence.

Osteitis pubis in professional soccer players: A report of outcome with symphyseal curettage in cases refractory to conservative management

Osteitis pubis is a painful, noninfectious disorder of uncertain etiology characterized by inflammation of the symphysis pubis in association with a number of conditions, including trauma, rheumatological disorders, pregnancy, and, increasingly in the modern era, with high level athletic exertion. Although most cases of osteitis pubis gradually resolve spontaneously or with conservative measures, there are, nevertheless, a small number of patients in whom the pain persists indefinitely, representing a possible career-ending problem for professional athletes, particularly with the repetitive microtrauma sustained by athletes participating in sports that involve running or kicking.

Simultaneous hip and upper limb fracture in the elderly: incidence, features and management considerations

We performed a retrospective analysis of all patients admitted to a single unit over 4 years with fractured neck of femur. Of the 760 patients admitted over this period of time 36 (4.7%) were found to also have a fracture of the upper limb. The associated upper limb fractures were distal radius (n=28), olecranon (n=2) and neck of humerus (n=5) and fifth metacarpal (n=1), with the same ratio of intracapsular to extracapsular fractures as the whole group. The female to male ratio in the isolated hip fracture group was 2.4:1 and for the combined fractures group was 8:1 (difference P=0.014). The mean patient age was 77.3 years for isolated hip fractures and 83.9 for the combined group (P=0.037). The mean total length of stay in hospital for isolated hip fracture was 15.6 days and for combined fractures was 20.4 days (P=0.010). We have demonstrated that combined upper limb and neck of femur fractures occur in a population that is older and predominantly female. They are associated with a significant increase in hospital stay and increased difficulties in mobilisation as a consequence of the combined fractures. It is therefore important to recognise this specific subgroup of patients presenting with hip fractures in order to ensure that they receive adequate treatment and rehabilitation and that the use of valuable health care resources are optimised.

Human Chondrocyte Viability After Treatment With Local Anesthetic and/or Magnesium: Results From an In Vitro Study

PURPOSE We aimed to assess the effect on chondrocyte viability of adding magnesium to a variety of commonly available local anesthetic agents. METHODS Human chondrocytes were grown under standard culture conditions. Cells were exposed to a local anesthetic agent with the addition of magnesium (10%, 20%, or 50%). Cells were also exposed to the varying concentrations of magnesium and 0.9% saline solution. Untreated cells served as controls. The CellTiter 96 AQueous One Solution Cell Proliferation Assay was used to assess for cell viability 24 hours after exposure. One-way analysis of variance was used to test for statistical significance. RESULTS Magnesium sulfate alone was no more toxic than normal saline solution (P > .3) compared with untreated cells. The addition of magnesium to the local anesthetic agents resulted in greater cell viability than when cells were treated with a local anesthetic alone (lidocaine [P = .033], levobupivacaine [P = .007], bupivacaine [P < .001], and ropivacaine [P < .001]). CONCLUSIONS Our findings support the use of magnesium either alone or in combination with a local anesthetic rather than a local anesthetic alone, and this represents a potential strategy for the reduction of chondrocyte toxicity associated with intra-articular local anesthetic administration after arthroscopy. CLINICAL RELEVANCE The addition of magnesium to a local anesthetic results in a reduced toxic effect to the articular chondrocyte. This may represent a potential approach to intra-articular analgesia.