BACKGROUND:

Impingement of the femoral neck with the acetabular component after metal-on-metal hip resurfacing arthroplasty (HRA) is a possible cause of edge loading and accelerated bearing wear. No attempt has been made to correlate radiographic impingement signs and blood metal ion levels. QUESTIONS/

PURPOSES:

We (1) compared serum cobalt (CoS) and chromium (CrS) concentrations between patients with and without radiographic impingement signs treated with unilateral HRA, (2) determined whether divot depth on the femoral neck correlated with CoS and CrS, and (3) assessed the predictive value of radiographic impingement signs for high levels of CoS and CrS.

METHODS:

A retrospective radiographic review of 141 patients with CoS and CrS analyses yielded 21 patients with and 120 without radiographic impingement signs (controls). Radiographic measurements included divot depth and orientation of the acetabular component to compute the contact patch to rim distance, a measure of functional head coverage. We defined a patient as having radiographic impingement signs if a remodeling of the femoral neck cortex showed a depression matching the predicted path of an impinging acetabular component. CoS and CrS were analyzed by inductively coupled plasma mass spectrometry and the radiographs were taken within 12 months of the last blood draw.

RESULTS:

Median CoS and CrS were greater in the impingement group than in controls in patients with less than 10-mm contact patch to rim distances. Divot depth did not correlate with CoS or CrS. In predicting elevated ion levels (≥ 7 μg/L), the presence of a radiographic impingement sign showed a sensitivity of 50% for CoS and 33% for CrS and a specificity of 87% for both CoS and CrS.

CONCLUSIONS:

Radiographic impingement signs influenced CoS and CrS only when the functional head coverage was insufficient due to poor socket positioning. Radiographic impingement signs alone were not a good predictor of elevated metal ion levels.

LEVEL OF EVIDENCE:

Level III, diagnostic study. See Instructions for Authors for a complete description of levels of evidence.

BACKGROUND:

Limited information is available regarding the incidence, risk factors, and optimal prophylaxis in orthopaedic oncology patients, although malignancy and major orthopaedic surgery are associated with an increased pulmonary embolism (PE) risk. QUESTIONS/

PURPOSES:

We aimed to investigate the incidence of PE after musculoskeletal tumor surgery in Japanese patients and analyze the potential risk factors for PE.

METHODS:

We retrospectively identified 3750 patients (1981 males, 1769 females) who underwent musculoskeletal tumor surgery during 2007 to 2010 using the Japanese Diagnostic Procedure Combination administrative database. Data collected included sex, age, primary diagnosis, type of surgery, duration of anesthesia, and comorbidities that may affect PE incidence. Univariate logistic regression analyses were performed to examine the relationship of each factor with PE occurrence.

RESULTS:

We identified 10 patients with PE during the survey period. A primary malignant bone tumor was associated with a significantly higher risk of PE than a primary malignant soft tissue tumor (odds ratio [OR], 5.58; 95% CI, 1.39-22.42). Bone tumor resection (OR, 7.94; 95% CI, 1.77-35.59) and prosthetic reconstruction (OR, 9.15; 95% CI, 1.52-55.07) were associated with a significantly higher risk of PE than soft tissue tumor resection.

CONCLUSIONS:

Malignant bone tumors and bone tumor resections have a higher risk of PE than malignant soft tissue neoplasms and soft tissue resections. Both populations might require PE prophylaxis as it is likely that the risk is greater than with other major orthopaedic surgery, but data accumulation should continue, and further investigation should be done to clarify details of the incidence, risk factors, and optimal prophylaxis for PE.

LEVEL OF EVIDENCE:

Level II, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.

BACKGROUND:

Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) have recently been suggested as diagnostic criteria for periprosthetic joint infection (PJI) diagnosis. Thresholds for these markers should be reexamined since they have been determined arbitrarily. QUESTIONS/

PURPOSES:

Based on recently defined criteria for PJI, we determined (1) whether there is a difference in the threshold value of ESR and CRP between hips and knees, (2) whether the threshold value for ESR and CRP should be different for early-postoperative and late-chronic PJI, and (3) the optimal thresholds for ESR and CRP in PJI diagnosis.

METHODS:

We retrospectively reviewed 1962 patients with revision arthroplasty for aseptic failure (1095 hips, 594 knees) or first onset of PJI (108 hips, 165 knees) between 2000 and 2009. The PJI diagnosis was made independent of ESR and CRP using criteria recently proposed by the Musculoskeletal Infection Society. Patients with comorbidities that confound ESR and CRP were not included. Receiver operating characteristic (ROC) analysis was performed to determine thresholds.

RESULTS:

ESR and CRP levels in late-chronic PJI were higher in knees than in hips. Optimal thresholds for ESR and CRP were 48.5 mm/hour and 13.5 mg/L in hips and 46.5 mm/hour and 23.5 mg/L in knees, respectively. In early-postoperative PJI, ESR and CRP were similar in both joints with common thresholds of 54.5 mm/hour and 23.5 mg/L, respectively.

CONCLUSIONS:

The data suggest a similar threshold for ESR but not for CRP should be implemented for late-chronic hips and knees. Optimal magnitudes are higher than conventional thresholds, indicating the need for refinement of thresholds if ESR and CRP are to be criteria for PJI diagnosis. Early-postoperative and late-chronic PJI might require different thresholds.

LEVEL OF EVIDENCE:

Level III, diagnostic study. See Instructions for Authors for a complete description of levels of evidence.

BACKGROUND:

The use of a highly conforming, anterior-stabilized bearing has been associated with clinical success in a limited number of studies. QUESTIONS/

PURPOSES:

We compared Knee Society scores, radiographic results, complication rates, and revision rates with the use of anterior-stabilized bearings compared with cruciate-retaining (CR) bearings.

METHODS:

A series of 382 patients with 468 primary total knee arthroplasties (TKAs) between 2003 and 2008 with minimum 2-year followup were reviewed. Anterior-stabilized bearings comprised 49% (n = 228) of the sample and CR bearings consisted of 51% (n = 240). The decision to use an anterior-stabilized bearing was based on integrity of the posterior cruciate ligament (PCL) intraoperatively or after sacrifice of the PCL to achieve soft tissue balance. The tibial and femoral component designs were the same regardless of bearing choice. Outcomes were measured with Knee Society scores, complications, revision TKA, and survival. Radiographs were analyzed for component alignment and evidence of loosening.

RESULTS:

There was no difference in Knee Society knee scores, radiographic alignment, component loosening, manipulation rate, major complications, or time to revision for patients between the two groups. However, the CR group had significantly more revisions than the anterior-stabilized group (21 CR [1.5%] versus seven anterior-stabilized [4.6%], p = 0.03) at a minimum followup of 5 months (mean, 42 months; range, 5-181 months).

CONCLUSIONS:

The use of a highly congruent anterior-stabilized bearing for PCL substitution has comparable clinical and radiographic results to traditional CR TKA. These results suggest that this approach is an effective method to achieve stability without the PCL in primary TKA.

LEVEL OF EVIDENCE:

Level III, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

BACKGROUND:

Analysis of arthrokinematics may have clinical use in the diagnosis of dynamic instability of the thumb and wrist. Recent technological advances allow noninvasive, high-resolution imaging of skeletal (thumb and carpal bones) structures during motion. QUESTIONS/

PURPOSES:

The primary purpose of this study is to define the arthrokinematics, estimated joint contact patterns, and distribution ratios of the carpometacarpal joint of the thumb using four-dimensional CT (three-dimensional CT + time) and registration algorithms. The second purpose is to validate the accuracy of the approach.

METHODS:

Four-dimensional CT scans were obtained using a nongated sequential scanning technique. Eighteen image volumes were reconstructed over a 2-second cycle during thumb circumduction in one healthy volunteer. Using a registration algorithm, serial thumb motions as well as estimated joint contact areas were quantified. To evaluate the accuracy of our approach, one cadaveric hand was used.

RESULTS:

During circumduction, the ranges of motion of the thumb carpometacarpal joint were: flexion-extension, 27.3°; adduction-abduction, 66.9°; and pronation-supination, 10°. The magnitude of the translation of the center of the estimated joint contact area of the metacarpal was 4.1, 4.0, 1.0, and 1.5 mm when moving from the initial key pinch position to adduction, adduction to palmar abduction, palmar abduction to opposition, and opposition to the initial key pinch position, respectively. The maximum estimated contact area on the trapezium and on the metacarpal was in palmar abduction; the minimum was in adduction. Dominant central-volar contact patterns were observed on both the trapezium and the metacarpal bone except in adduction. This analysis approach had an average rotational error of less than 1°.

CONCLUSIONS:

During circumduction, the estimated joint contact area was concentrated on the central-volar regions of both the trapezium and the metacarpal bones except when the thumb was adducted.

CLINICAL RELEVANCE:

This tool provides quantification of estimated joint contact areas throughout joint motion under physiological dynamic loading conditions; this tool may, in future studies, help to clarify some of the ways that joint mechanics might or might not predispose patients to arthritis.

BACKGROUND:

The treatment of displaced, intraarticular calcaneal fractures (DIACFs) remains challenging and the best treatment choices remain controversial. The majority of patients will have some lasting functional restrictions. However, it is unclear which patient- or surgeon-related factors predict long-term function. QUESTIONS/

PURPOSES:

We determined (1) the impact of patient- and surgeon-related factors on function of patients after internal fixation of DIACFs and (2) whether severity of injury correlated with subsequent function.

METHODS:

We retrospectively reviewed all 210 patients operatively treated for 242 DIACFs between 2000 and 2003; of these, 127 patients (60%) with 149 fractures were available for followup at a minimum of 69 months (average, 95 months; range, 69-122 months). Severity of injury was quantified by the classifications of Sanders and Zwipp Function was quantified using the American Orthopaedic Foot and Ankle Society (AOFAS) Ankle-Hindfoot score, an adjusted Zwipp score, the Foot Function Index (FFI), and the SF-36 physical and mental component summary (PCS and MCS) scores.

RESULTS:

At latest followup, the median AOFAS score was 77, the median Zwipp score was 60, the median FFI was 27, and the median SF-36 PCS and MCS scores were 44 and 55, respectively. The foot-related scores and the SF-36 PCS negatively correlated with the severity of injury, work-related injuries, and bilateral fractures.

CONCLUSIONS:

We found the severity of a DIACF related to subsequent foot function and quality of life. Both fracture severity classifications predicted function. Anatomic reconstruction of the shape and articular surfaces of the calcaneus leads to predictable function in the medium to long term.

LEVEL OF EVIDENCE:

Level IV, prognostic study. See Instructions for Authors for a complete description of levels of evidence.

BACKGROUND:

The use of retrograde nailing for gunshot wound femur fractures is controversial due to concerns of knee sepsis after this procedure since the knee is entered to introduce the nail into the canal. QUESTIONS/

PURPOSES:

We compared retrograde and antegrade nailing for gunshot femur fractures to determine whether (1) knee sepsis or other adverse events were more likely to complicate procedures using retrograde nails, (2) there were differences in surgical time or blood loss, and (3) there were differences in radiographic union.

METHODS:

We retrospectively reviewed our prospective trauma database from 1999 to 2012 for patients with a diagnosis of gunshot and femur fracture. We performed a detailed review of medical records and radiographs for those patients with OTA Classification Type 32 femur fractures secondary to gunshot injury treated with either retrograde or antegrade femoral nailing. Eighty-one patients were treated with intramedullary nailing (53 retrograde and 28 antegrade). We reviewed elements of the operative treatment (procedure, anesthesia time, operative time, and estimated blood loss) for all 81 patients. For clinical and radiographic review, followup was adequate for 43 and 25 patients with retrograde and antegrade nailing, respectively. Minimum followup was 3 months for both groups (retrograde: mean, 41 months; range, 3-148 months; antegrade: 26 months: range, 3-112 months).

RESULTS:

No patients in either group developed knee sepsis. No significant differences were found between groups with regard to operative time, blood loss, or radiographic union.

CONCLUSIONS:

With the numbers available, immediate retrograde nailing appears as safe and effective as antegrade nailing for gunshot femur fractures. Immediate retrograde nailing is as safe as antegrade nailing for gunshot femur fractures.

LEVEL OF EVIDENCE:

Level III, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.