Morbidity and Safety of Iliac Crest Reference Array Pins in Navigated Total Hip Arthroplasty: A Prospective Cohort Study.

BACKGROUND: Navigated total hip arthroplasty (THA) can employ intra-osseous pins through a separate incision to secure reference arrays to the iliac crest. This study is the first to investigate the consequences of pin use in THA in vivo. METHODS: A prospective, consecutive series of 43 patients presenting for navigated THA were included. Two temporary 125 × 4 mm Schanz screws were inserted into the iliac crest for the attachment of a reference array. Telephone follow-up occurred at 6 and 12 weeks post-operatively. Patients were asked about pain, interference with daily activities, how often the wound was noticed, and duration of discomfort. Patient body mass index was recorded. RESULTS: The follow-up rate was 100%. Pin site pain at any time post-operatively was reported by 24 patients (56%). This improved to 30%, 9%, and 2% at 3, 6, and 12 weeks, respectively. On average, pain lasted for 16 days total. The most common complaints after pain were clothing discomfort (23%), pain when wearing a belt (12%), or pain when mobilizing (9%). For the majority (98%) of patients, all symptoms had resolved by 12 weeks. There was no nerve injury, pin site fracture, infection, or screw breakage. Patients with body mass index greater than 30 kg/m2 were up to 3 times more likely to experience pin site pain (P = .05), and had a longer duration of pain (P = .04). CONCLUSION: Surgeons and patients should be aware that using navigational pins for array fixation carries low complication rates but often will cause pain and irritation that resolves in the short term.

Outcomes following operatively managed acetabular fractures in patients aged 60 years and older.

AIMS: Acetabular fractures in older adults lead to a high risk of mortality and morbidity. However, only limited data have been published documenting functional outcomes in such patients. The aims of this study were to describe outcomes in patients aged 60 years and older with operatively managed acetabular fractures, and to establish predictors of conversion to total hip arthroplasty (THA). METHODS: We conducted a retrospective, registry-based study of 80 patients aged 60 years and older with acetabular fractures treated surgically at The Alfred and Royal Melbourne Hospital. We reviewed charts and radiological investigations and performed patient interviews/examinations and functional outcome scoring. Data were provided by the Victorian Orthopaedic Trauma Outcomes Registry (VOTOR). Survival analysis was used to describe conversion to THA in the group of patients who initially underwent open reduction and internal fixation (ORIF). Multivariate regression analyses were performed to identify factors associated with conversion to THA. RESULTS: Seven patients (8.8%) had died at a median follow-up of 18 months (interquartile range (IQR) 12 to 25), of whom four were in the acute THA group. Eight patients (10%) underwent acute THA. Of the patients who underwent ORIF, 17/72 (23.6%) required conversion to THA at a median of 10.5 months (IQR 4.0 to 32.0) . After controlling for other factors, transport-related cases had an 88% lower rate of conversion to THA (hazard ratio (HR) 0.12, 95% confidence interval (CI) 0.02 to 0.91). Mean standardized Physical Component Summary Score (PCS-12) of the 12-Item Short Form Health Survey (SF-12) was comparable with the general population (age-/sex-matched) by 12 to 24 months. Over half of patients working prior to injury (14/26) returned to work by six months and two-thirds of patients (19/27) by 12 months. CONCLUSION: Patients over 60 years of age managed operatively for displaced acetabular fractures had a relatively high mortality rate and a high conversion rate to THA in the ORIF group but, overall, patients who survived had mean PCS-12 scores that improved over two years and were comparable with controls. Cite this article: Bone Joint J 2020;102-B(12):1735-1742.

Haemosiderotic Synovitis Secondary to Anticoagulant Use: An Unusual Mechanism of Failure of a Unicompartmental Knee Replacement.

Haemosiderotic synovitis is a rare condition caused by recurrent or chronic haemarthroses. This may lead to intra-articular destruction, a painful joint, and, if untreated, ankylosis of the joint. We highlight a case of an elderly lady who presented to an orthopaedic clinic with left knee pain, following recurrent left knee atraumatic haemarthroses secondary to oral anticoagulant use. At her presentation, she had a left medial unicompartmental knee prosthesis in situ. Weight bearing radiographs of the left knee showed marked loss of lateral joint space with valgus alignment. These radiographic findings were not present on the radiographs taken at her first presentation with haemarthrosis nine months previously. A left revision total knee arthroplasty was performed, and a diagnosis of haemosiderotic synovitis was made following histological analysis of intraoperative tissue samples. This case highlights an unusual mechanism of failure of a unicompartmental knee replacement. Though haemosiderotic synovitis is an exceedingly rare condition, it must be considered following recurrent haemarthrosis as, due to its destructive nature, prompt recognition and treatment is paramount.

A novel fluoroscopic approach to assessing patient positioning in total hip arthroplasty: accuracy and the influence of body mass index.

INTRODUCTION: Accurate prosthetic cup placement is important in total hip arthroplasty (THA) and can be influenced by patient positioning. This study aims to assess the accuracy of patient positioning prior to THA, describe a new technique of assessment, and evaluate the influence of body mass index (BMI) on positioning error. METHODS: A consecutive series of 37 patients undergoing unilateral THA were investigated. After patient positioning in lateral decubitus, a lateral fluoroscopic image through the table was taken. The C-arm of the image intensifier was manipulated in 2 planes (coronal, transverse) until a perfect lateral view of the pelvis was obtained, defined as when the native acetabulae were superimposed. Degrees of positioning error in the 2 planes were recorded, along with patient BMI. RESULTS: There were 6 patients (16%) positioned within 2° of true lateral in both planes. A further 21 patients (57%) had an error of 5° or more in at least 1 plane. Mean absolute positioning error was 3.0° (SD 2.2°; range 0°-9°) and 3.0° (SD 3.2°; range 0°-13°) in the transverse and coronal planes respectively. Pelvic adduction in the coronal plane was 4.5 fold more likely than abduction (49% vs. 11%). Correlation was shown between patient BMI and the combined error in the 2 planes (R = 0.48, p = 0.001). DISCUSSION: Fluoroscopic positioning assessment prior to THA demonstrates that significant malpositioning is common and more likely with increasing BMI. This technique may be particularly useful for patients with a BMI of >30 kg m-2.

Nerve fibers in lumbar spine structures and injured spinal roots express the sensory neuron-specific sodium channels SNS/PN3 and NaN/SNS2.

STUDY DESIGN: This prospective study examined the innervation of lumbar spine in tissues from patients with lower back pain and spine nerve roots from patients with traumatic brachial plexus injuries. OBJECTIVES: To demonstrate the presence of nerve fibers in lumbar spine structures and spine nerve roots, and to determine whether they express the sensory neuron-specific sodium channels SNS/PN3 and NaN/SNS2. SUMMARY OF BACKGROUND DATA: The anatomic and molecular basis of low back pain and sciatica is poorly understood. Previous studies have demonstrated sensory nerves in the facet joint capsule and prolapsed intervertebral disc, but not in the ligamentum flavum. The voltage-gated sodium channels SNS/PN3 and NaN/SNS2 are expressed by sensory neurone that mediate pain, but their presence in the lumbar spine is unknown. METHODS: Tissue samples of ligamentum flavum (n = 32), facet joint capsule (n = 20), intervertebral disc (n = 15), and spine roots (n = 8) were immunostained with specific antibodies to protein gene product 9.5 (a panneuronal marker), SNS/PN3, and NaN/SNS2. RESULTS: Protein gene product 9.5 immunoreactive nerve fibers were detected in 72% of the ligamentum flavum specimens and 70% of the facet joint capsule specimens, but in only 20% of the intervertebral disc specimens. The study detected SNS/PN3- and NaN/SNS2-positive fibers, respectively, in 28% and 3% of the ligamentum flavum specimens and 25% and 15% of the facet joint capsule specimens. Numerous SNS/PN3- and NaN/SNS2-positive fibers were found in the acutely injured spine roots, and some were still present in the dorsal roots in the chronic state. CONCLUSIONS: As the findings showed, SNS/PN3- and NaN/SNS2-immunoreactivity is present in a subset of nerve fibers in lumbar spine structures, including ligamentum flavum, and in injured spine roots. Selective SNS/PN3- and NaN/SNS2-blocking agents may provide new therapy for back pain and sciatica.