Clinical observations suggest mid-flexion instability may occur more commonly with rotating platform (RP) total knee arthroplasty (TKA), including increased revision rates and patient-reported instability and pain. We propose that increased gap laxity leads to liftoff of the lateral femoral condyle with decreased conformity between the femoral component and polyethylene (PE) insert surface leading to PE subluxation or dislocation. The objectives of this study were to define “at risk” loading conditions that predispose patients to PE insert subluxation or spinout, and to quantify the margin of error for flexion/extension gap laxity in preventing these adverse events under physiologic loading conditions. Biomechanical testing was performed on six fresh frozen cadaveric knees implanted with a posterior stabilized RP TKA using a gap balancing technique. Rotational displacement and torque were measured over time, while stiffness, yield torque, max torque and displacement were calculated using a post-processing, custom MatLab code. Revision with varying size femoral components (size 3–6) and PE insert thicknesses (10–15mm), by downsizing one step, were used to create a spectrum of flexion/extension gap mismatch. Each configuration was subjected to three loaded testing conditions (0°, 30° and 60° flexion) in balanced and eccentric varus loading, known to represent daily clinical function and “at risk” circumstances.Introduction
Methods
Several surgical approaches are available for elective total hip arthroplasty (THA) for osteoarthritis. While posterior surgical approaches are the most common, interest in a direct anterior (Hueter) approach is increasing because of alleged advantages in convalescence. However, no studies have examined differences in patient-reported global and condition-specific measures of health across multiple institutions. The ongoing Pulmonary Embolism Prevention after Hip and Knee Replacement (PEPPER) study is a PCORI-funded multicenter pragmatic clinical trial randomizing patients to three different antithrombotic regimens. We analyzed operative data from PEPPER to compare pre-post changes in validated patient-reported outcome measures after THA based on surgical approach. Participants (age 21 or older) were recruited from 27 academic medical centers for the PEPPER trial. Eligibility screening, baseline measures, and operative detail were entered into a central database with standardized blinded post-operative data collection protocol. We included participants undergoing elective primary total hip arthroplasty, excluding those undergoing revision, resurfacing, bilateral procedures, on chronic preoperative anticoagulation, with a recent history of gastrointestinal, cerebral, or other hemorrhage, defective hemostasis, or uncontrolled hypertension. Participating centers reported the operative approach as “Posterior”, “Transgluteal”, or “Anterior”. The brief version of the Hip Dysfunction and Osteoarthritis Outcome Score (HOOS Jr.) and the Patient Reported Outcome Measurement Information System Global Survey (PROMIS10) were ascertained pre-operatively, and at 1, 3 and 6 months post-operatively. Mixed-effects linear regression was used to compare difference in patient-reported outcomes over time based on surgical approach, adjusting for baseline measures of health outcome, patient age, sex, race, ethnicity, BMI, comorbidity, education, work status, alcohol use, and smoking status.Introduction
Methods
Total joint arthroplasty (TJA) is a high value elective orthopaedic procedure, the indications for which may vary among surgeons as well as patients. The utilization of other discretionary procedures is known to be influenced by the availability of qualified surgeons. We investigated the existence of a correlation between geographic variation in TJA utilization and the regional density of arthroplasty surgeons. The number of Medicare-funded total hip (THA) and total knee (TKA) arthroplasties performed in predetermined geographic referral regions were obtained from the Dartmouth Atlas for 2012. The number of surgeons specializing in total joint arthroplasty in each respective region was derived from the AAHKS membership list. Linear regression was used to assess the relationship between number of arthroplasties performed per 1000 Medicare beneficiaries and the number of AAHKS-members per 100,000 beneficiaries in each Hospital Referral Region (HRR). For THA in aggregate, a positive correlation was found between number of THA performed per 1,000 beneficiaries and increasing TJA surgeon density. Positive correlations were also noted when HRRs were stratified by size from 50,000 to 250,000 beneficiaries. The number of THA performed per 1,000 beneficiaries in regions with AAHKS members was greater than in regions without (4.03 vs 3.29; p=0.008). In contrast, there was no correlation between the rate of TKA utilization and HRR surgeon density, and no consistent relationship between TKA rate and HRRs stratified by size. Likewise, there was no difference in the rate of TKA between HRRs with and without AAHKS members (8.48 vs 8.84; p=0.18). The frequency of THA positively correlates with AAHKS surgeon density in all but the largest HRRs and was greater in regions with AAHKS members than in those without. Such relationships were not apparent for TKA utilization. These data may have important implications for more cost-effective utilization of THA.
“Like other craftsmen, we have often two ways at least of doing the same job, the success of which is dependent upon the character and the integrity of the man. “Approaches” are for us both physical and psychological: in the case of the hip joint it seems clear that there is more than one good method and that, for the sake of those we train, we should keep an open mind.” Orientation relative to the abductor musculature and ease of access to the pathology in question should provide the compelling basis for selection of operative approaches to the hip, rather than being based solely on surgeon habit. Approaches to primary total hip arthroplasty remain the surgeon's choice; posterior approaches provide challenges to cup orientation and anterior approaches offer more difficult access to the proximal femur. Imperatives for a decubitus position posterior approach include pelvic dissociation with need for posterior column plating, removal of retained posterior hardware, and sciatic neurolysis after prior injury. Conversely, indications for a supine anterolateral approach include an isolated acetabular revision with a well-fixed femoral stem and the need for retroperitoneal removal of an intrapelvic acetabular component. Transgluteal approaches inflict potentially the greatest damage to the abductor musculature and are best reserved for primary operative settings; stability of a femoral endoprosthesis is optimised through this approach by preserving the posterior capsular structures. The transtrochanteric approach provides unrivaled exposure to both pelvis and acetabulum from either a supine or decubitus position, and is most helpful for removal of long well-fixed femoral stems whether cemented or cementless.
Conventional wisdom holds that aseptic failure of proximal ingrowth femoral stems should be addressed by revision to a longer femoral stem dependent upon more distal fixation. This is a reliable and time-honoured strategy with a high likelihood of success provided secure initial fixation of the revision stem is obtained. Yet, stems reliant upon more distal diaphyseal fixation are accompanied by a greater risk of physiologic thigh pain attributable to the differential in flexural stiffness of the femoral shaft compared with the prosthetic stem. Contemporary proximal ingrowth femoral stems have become the most popular device used in total hip arthroplasty and are traditionally reserved for primary procedures. Nevertheless, the flat tapered design offers a tight fit between the medial and lateral endosteal cortices of the femur, unimpeded by an increasing anteroposterior dimension of the stem, and provides a secure geometrical block to rotational movement of the stem. In instances when the primary stem is not fit to the endosteal cortex on the anteroposterior radiograph, such as with the Corail or SROM devices, the opportunity may exist for revision with a flat tapered proximal ingrowth stem that is upsized to abut the endosteal femoral cortex. Such a strategy preserves the diaphyseal femur for subsequent revision in these typically young patients and avoids the issue of thigh pain in this active population. Likewise, revision of a well-fixed long stem that is associated with unrelenting thigh pain may be similarly accomplished by revision to a flat proximal ingrowth stem provided the integrity of the upper femur can be maintained during the revision. A prophylactic cerclage wire around the proximal femur is a helpful adjunct when using flat tapered proximal ingrowth stems in the revision setting.
The Accreditation Council of Graduate Medical Education (ACGME) has formalized a limit of 16 consecutive duty hours for first year and 20 hours for intermediate level trainees, while maintaining a maximum of 80 duty hours per week despite social pressure to further reduce this limit. Deterioration in cognitive and technical performance secondary to fatigue is the basis for the 16 hour rule, along with the notion that “strategic napping” be strongly encouraged for trainees that must remain for longer shifts. For more senior trainees, graduated independence and responsibility are recognized as important to prepare for the independent practice of medicine. Yet, a reduction of nearly 7000 hours, or the equivalent of 2 years of surgical education and experience, results from the 80-hour duty limitation compared to surgical training of two decades ago. The contention is that duty hours must be constrained to optimize patient safety and the learning environment, but it is unclear whether mastery of the necessary cognitive and technical competencies can be achieved in such a constricted time period. Another worrisome by-product of legislated duty hour limitations is the unintended encouragement of a “shift worker” mentality and erosion of the ethos of professionalism among trainees. Effective mentoring takes on critical importance in this challenging environment, yet productive mentoring may be counter to learned adaptive behaviours and instinctive personality traits of some accomplished surgeon educators. Fostering effective mentors in academic surgery requires us to develop behaviors that are conducive to the mentoring process. As our trainees struggle to achieve mastery of a surgical discipline within a prescribed and constricted time period, we must consider a competency-based system of surgical education rather than one that is time-defined. Likewise, the personal and professional growth of our trainees in this system, as well as the succession planning for our specialty, are dependent upon the creation of an environment conducive to effective mentoring in academic orthopaedics.
