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The fluoroscopically assisted direct anterior approach for total hip arthroplasty has gained interest in recent years. One of the perceived advantages is the use of fluoroscopy to aid in the positioning of implants. The purpose of this study was to measure the radiation entrance surface dose to anatomically important areas of both patients and surgeons during direct anterior approach total hip arthroplasty.Radiation dosimetry badges were placed at the sternal notch and pubic symphysis of 50 patients undergoing direct anterior approach total hip arthroplasty. Badges were also placed on the surgeons outside of their lead aprons at the level of the thyroid. Three fellowship-trained arthroplasty surgeons were involved in the study. Radiation exposure of each badge was measured after each case (surgeon and patient). The cumulative dose was also calculated for the surgeons. To limit surgeon bias during the study, 50 consecutive direct anterior approach total hip arthroplasties that occurred prior to this study were analyzed for total fluoroscopic dose and time and served as a control group.Forty-five subjects met study criteria. In the study group, 1 patient had a detectable thyroid exposure equal to 1 mrem. Seven patients had a detectable radiation entrance surface dose at the pubic symphysis (range, 1 to 7 mrem). No radiation entrance surface dose was detectable in the remaining 44 patients at the sternal notch and 38 patients at the pubic symphysis. Surgeons in the study did not experience a detectable radiation entrance surface dose. The mean fluoroscopic time was 13.72 seconds (range, 6.7 to 28.7 seconds). The mean patient radiation exposure was 178 mrem (range, 54 to 526 mrem).This study demonstrates that during direct anterior approach total hip arthroplasty, the mean patient entrance surface dose at the pubic symphysis and the sternal notch is not detectable in most patients. The mean patient exposure in this study during direct anterior approach total hip arthroplasty was 178 mrem, which is less than a single pelvic radiograph (600 mrem). No surgeon in our study demonstrated a detectable radiation entrance surface dose. Our data suggest that direct anterior approach total hip arthroplasty typically results in a negligible or very low dose of absorbed radiation exposure to the patient and the surgeon.We believe this study to have clinical relevance because both patients and surgeons have evidence that utilization of fluoroscopy during direct anterior total hip replacement places both parties at a relatively low radiation exposure risk.

Background In the setting of acetabular deficiency during total hip arthroplasty (THA), the medial protrusio technique (MPT) allows for increased component coverage while avoiding excessive component abduction or elevation of the hip center. The technique involves controlled reaming through the medial acetabular wall while maintaining the continuity of the anterior and posterior columns. The purpose of this study is to analyze the results of the largest reported series to date of primary and revision THAs using the MPT. Methods A retrospective review of THAs performed by a single surgeon from July 2004 to July 2010 identified 102 patients who underwent THA necessitating the use of the MPT (primary 86 and revision 16), with at least 2 years follow-up. Results This study reports the largest series to date of primary and revision THAs using the MPT for acetabular deficiency. Postoperatively, mean Harris hip score was 86 (range 31-96). There was no correlation with degree of medialization and change in Harris hip score (P = .12). At mean follow-up of 41.1 months (range 24-92 months), there were no intrapelvic structure injuries and no acetabular components required revision. The MPT provided a safe and effective method for addressing acetabular deficiency and avoiding component malposition. Conclusion The MPT provided a safe and effective method for addressing acetabular deficiency in this large series of patients. The technique was successful at improving component coverage while maintaining an anatomic hip center and avoiding excessive component abduction. Fixation remained durable with no cases of loosening at final follow-up.

Despite the clear importance of the operative report in the electronic medical record, few studies have addressed the quality.We prospectively evaluated 300 consecutive patients undergoing primary total joint arthroplasties for operative report errors utilizing three different forms of documentation (standard dictation vs. templated dictation vs. a computer registry database generated operative report). The three types of reports were evaluated for errors which were classified as either major or minor.There were significantly more total errors in the standard dictation group compared to both the computer registry database generated (p0.001) and the templated operative reports (p0.001). Major errors were significantly reduced in the database generated reports compared to the templated (p0.001) and standard dictation groups (p0.001). There were significantly more minor errors in the standard dictation group (p0.001) compared to the other two groups. No statistically significant differences in major errors were noted when comparing standard vs. templated operative reports. There was no difference in minor or total errors between the database generated and templated operative reports.The use of a computer registry database generated operative report resulted in fewer major errors versus a templated or standard dictated operative report. Further research is warranted in this area to validate these findings across subspecialties and institutions.

Background Patellofemoral crepitus is a known complication of posterior stabilized (PS) total knee arthroplasty (TKA). This study compared the incidence of patellofemoral crepitus between two femoral components designs. Materials and Methods Between January 2005 and August 2010, 1,120 patients with complete 2-year follow-up had a PS TKA with two different prosthetic designs (group A, 553 patients; group B, 567 patients). Records were reviewed to identify the incidence of total, symptomatic, and operative patellofemoral crepitus. Results No statistical differences were observed in the incidence of total patellofemoral crepitus (group A 14.1%, group B 14.5%; p = 0.932) or symptomatic patellofemoral crepitus (group A 5.6%, group B 4.2%; p = 0.334). The incidence of operative crepitus was greater in group A (3.3%) than in group B (1.3%; p = 0.026). Analysis of mobile versus fixed bearing designs showed a higher incidence of total patellofemoral crepitus in mobile bearing TKA (16.04 vs. 4.93%; p = 0.006) within group B only. Conclusion Femoral component design with a smoother intercondylar box transition zone resulted in a lower incidence of operative patellofemoral crepitus. No statistical differences were noted regarding the incidence of total and symptomatic patellofemoral crepitus. Mobile bearing TKA exhibited greater total crepitus within group B. Level of Evidence Level III.

The authors report the case of an atraumatic femoral component fracture 10 years after primary total knee arthroplasty (TKA) with a modern cemented fixed bearing system. The patient, a 70-year-old man, had the complication without inciting trauma, and he subsequently had severe pain and disability. This rare mode of TKA failure occurred at the superolateral aspect of the femoral component’s anterior flange. At the time of revision, no femoral osteolysis was seen and the backside of the prosthesis fracture fragment was found to be free of cement. To the authors’ knowledge, this is the first case of femoral component fracture in a Vanguard TKA (Biomet, Warsaw, Indiana), and the first case of fracture in a modern cobalt-chrome alloy femoral component associated with aseptic cement debonding. Femoral component stress fracture is a rare but serious complication of TKA. Reports of femoral component fracture in early designs were attributed to geometric design flaws, whereas modern TKA designs appear to fail when ingrowth failure, aseptic debonding, or osteolysis result in inadequate bony support of the prosthesis. Careful attention to bone cuts in porous-coated uncemented TKA systems and proper cementing technique in cemented TKA systems may preclude this rare complication. In the case of severe osteolysis, early revision may prevent catastrophic implant failure. [ Orthopedics . 2020;43(5):e476–e479.]

IntroductionPhysiologic strain patterns of the femur are altered by the bending stiffness of the implant as well as the loading pattern of the implant itself. The Savish Range of Motion (S-ROM) femoral stem has been designed with flutes (to decrease distal material) and with a coronal slot (to decrease stiffness).MaterialsThe purpose of this case report is to briefly discuss design characteristics of femoral stems and their relationship to thigh pain as well as to describe the only report in the literature of a fracture of the anterior spline of a S-ROM prosthesis at the coronal slot.ResultsThe femoral stem fractured at the coronal slot due to multiple bending moments in a small diameter stem.ConclusionsThe proximal metaphyseal sleeve remains well fixed and the patient is functioning well without pain nearly a year after the identification of the fracture on routine follow-up.

Study design Patellar tendon reflexes were elicited among patients who had had a unilateral total knee replacement, those planned for unilateral total knee replacement, and a cohort of controlled patients. Patellar tendon reflex (PTR) response was measured with surface electromyography. Objective The aim of this study was to determine if total knee arthroplasty significantly alters the PTR. Summary of background data As part of the clinical evaluation of the spine, extremity reflexes are provoked. Reflex variation between right and left extremities can be a pathological finding in disease of the spine. It has been noted that in patients who have undergone total knee arthroplasty (TKA), the PTR is diminished on the operative side compared with the contralateral nonoperative side. PTR is part of the clinical exam when evaluating a patient for lumbar radiculopathy. Methods The right and left patellar tendon reflex intensities were measured by quadriceps surface electromyography in 3 groups of patients. Group 1 consisted of 21 patients with unilateral TKA who were at least 6 months postoperative. Group 2 consisted of 18 patients with unilateral severe knee arthritis indicated for TKA. Group 3, serving as the control group, included 20 patients with no evidence of knee arthritis in either knee. The average reflex response for each group was recorded and comparisons were then made between each group. Results Patients who have undergone unilateral TKA have a PTR on average of 55.1% of their contralateral uninvolved side. This is statistically significant when compared with reflexes in patients who are planned for unilateral total knee arthroplasty, 96.03% (P = 0.001) and when compared with patients without evidence for knee arthritis, 102.2% (P Conclusion The results of this case control study show that TKAs do significantly diminish PTRs when compared with a contralateral uninvolved knee in the same patient. Level of evidence 3.

Background Use of leukocyte esterase (LE) testing of synovial fluid as an adjunct to the infection workup in total joint arthroplasty patients has been advocated. The purpose of this study was to determine the false positive rate of this test. Methods Two hundred patients with the diagnosis of degenerative osteoarthritis undergoing a total knee arthroplasty were identified for this study. The knee joint was aspirated under sterile conditions before performing the total knee arthroplasty. The fluid was analyzed with an LE reagent strip. Results There were 27 bloody and 17 dry aspirations. One hundred forty-nine patients produced an aspiration that allowed for LE testing. There was 1 positive LE result. The specificity of the LE test was found to be 99.3%. Conclusion These data suggest the LE strip as a part of the workup for infection in a native knee should yield few false positive results.

Synovial fluid aspiration is a routine practice used by most orthopaedic surgeons to aid in the diagnosis of joint infection. In patients for whom there is a low pretest probability of infection, a positive culture—particularly if it is a broth-only culture—may be considered a contaminant, especially if the bacterial species are skin pathogens. To our knowledge no study has evaluated the incidence of contamination of aspirations from the native knee. What is the frequency of false-positive cultures among knee aspirations of the native knee? Two hundred patients, with a total of 200 knees, with the diagnosis of degenerative osteoarthritis undergoing a total knee arthroplasty (TKA) were identified for this study. None of these patients had symptoms, signs, or laboratory studies to suggest the presence of joint infection; a positive culture in this population therefore would be considered contaminated. Thirty–two (16%) patients were excluded secondary to a dry aspiration. One patient was enrolled in the study but did not have the knee aspirated and another patient’s specimen was accidentally discarded. Each knee was aspirated under sterile conditions before performing the TKA. The fluid was sent for cell count and culture. If insufficient fluid was obtained for both cell count and culture, culture was performed rather than cell count. There were no false-positive cultures (zero of 166 [0%]) in aspirations of native knees. Our study would indicate that when done properly under sterile technique, cultures taken from knee arthrocentesis in patients without prosthetic joints should not be affected by perceived contaminant species. A positive specimen finding on culture should raise a strong suspicion of bacterial septic arthritis. Future studies should include more specimens as well as knees with prior TKA to help further identify the rate of false-positive cultures in knee arthrocentesis in both populations. Level I, diagnostic study.

Patellar crepitus is a complication most commonly seen in patients implanted with a posterior-stabilized total knee arthroplasty (TKA). Recently, design changes in the patellofemoral geometry and the intercondylar box ratio have been optimized in newer TKA designs. A comparative study was performed to analyze the incidence of patellar crepitus between a historical vs modern TKA design.A retrospective review of all patients at our institution that underwent a primary TKA with either a PFC Sigma or Attune posterior-stabilized TKA (DePuy, Inc, Warsaw, IN), with a minimum of 1-year follow-up duration was performed. A total of 1165 participants implanted with the PFC Sigma and 728 with the Attune design were analyzed. Patellar crepitus incidence, functional scores, and range of motion were recorded at each follow-up appointment. Statistical analyses were performed between the 2 groups to determine if there were differences in clinical outcomes.The incidence of crepitus in participants implanted with the Attune was 0.55% vs 6.26% in the PFC Sigma cohort (P.001) at 1 year vs. 0.83% vs 9.4%, respectively at 2 years post operatively (P.001). There were small differences in extension, flexion, and Knee Society Scores between the 2 groups that were not clinically meaningful.The Attune posterior-stabilized TKA demonstrated substantially less patellofemoral crepitus incidence than the historical control. We hypothesize that these findings are related to femoral component changes including a thinner and narrower anterior flange and a reduced femoral intercondylar box ratio.

Total knee arthroplasty (TKA) has shown to portend good long-term survivorship and excellent patient satisfaction. There are various etiologies of failure of a TKA. Instability is a major cause of the need for revision. Often, increased constraint is needed to supplement or perform the function of incompetent ligament and soft tissue structures. Posterior cruciate retaining (PCR) TKA has the least constraint. Posterior cruciate substituting (PS) TKA increases sagittal constraint. Varus–valgus constraint (VVC) adds a marked increase in coronal stability. The ultimate in constraint in TKA is a linked hinged implant. In revision TKA, it is the surgeon's responsibility to implant the prosthesis with the necessary constraint to impart adequate stability.