Braden McKnight

Spinopelvic mobility and acetabular component position for total hip arthroplasty

Aims Posterior tilt of the pelvis with sitting provides biological acetabular opening. Our goal was to study the post‐operative interaction of skeletal mobility and sagittal acetabular component position. Materials and Methods This was a radiographic study of 160 hips (151 patients) who prospectively had lateral spinopelvic hip radiographs for skeletal and implant measurements. Intra‐operative acetabular component position was determined according to the pre‐operative spinal mobility. Sagittal implant measurements of ante‐inclination and sacral acetabular angle were used as surrogate measurements for the risk of impingement, and intra‐operative acetabular component angles were compared with these. Results Post‐operatively, ante‐inclination and sacral acetabular angles were within normal range in 133 hips (83.1%). A total of seven hips (4.4%) had pathological imbalance and were biologically or surgically fused hips. In all, 23 of 24 hips had pre‐operative dangerous spinal imbalance corrected. Conclusions In all, 145 of 160 hips (90%) were considered safe from impingement. Patients with highest risk are those with biological or surgical spinal fusion; patients with dangerous spinal imbalance can be safe with correct acetabular component position. The clinical relevance of the study is that it correlates acetabular component position to spinal pelvic mobility which provides guidelines for total hip arthroplasty.

Surgical management of midshaft clavicle nonunions is associated with a higher rate of short-term complications compared with acute fractures.

BACKGROUND Little is known about the perioperative complication rates of the surgical management of midshaft clavicle nonunions. The purpose of the current study was to report on the perioperative complication rates after surgical management of nonunions and to compare them with complication rates of acute fractures using a population cohort. METHODS The American College of Surgeons National Surgical Quality Improvement Program database was queried to identify patients who had undergone open reduction-internal fixation of midshaft clavicle fractures between 2007 and 2013. Patients were stratified by operative indication: acute fracture or nonunion. Patient characteristics and 30-day complication rates were compared between the 2 groups using univariate and multivariate analyses. RESULTS A total of 1215 patients were included in our analysis. Of these, 1006 (82.8%) were acute midshaft clavicle fractures and 209 (17.2%) were midshaft nonunions. Patients undergoing surgical fixation for nonunion had a higher rate of total complications compared with the acute fracture group (5.26% vs. 2.28%; P = .034). On multivariate analysis, patients with a nonunion were at a >2-fold increased risk of any postsurgical complication (odds ratio, 2.29 [95% confidence interval, 1.05-5.00]; P = .037) and >3-fold increased risk of a wound complication (odds ratio, 3.22 [95% confidence interval, 1.02-10.20]; P = .046) compared with acute fractures. CONCLUSION On the basis of these findings, patients undergoing surgical fixation for a midshaft clavicle nonunion are at an increased risk of short-term complications compared with acute fractures. This study provides additional information to consider in making management decisions for these common injuries.

Instability (INS)/Dislocation (DISL)

(a) Epidemiology The incidence ranges from 0.2 to 7% for primary and 5 to 25% for revision THA [1–3]. INS is the third reason of revision THA following loosening and infection but the first reason of early revision. Greater than 50% of DISLs occur within three months postoperatively [4, 5]. The risk of recurrence following the first episode is estimated up to 33% [4]. (b) Types [4–7] 1. Early dislocation [6, 7] It occurs during the first 3–6 postoperative months. It is the most common type (50–70%). The inadequate healing and other preoperative risk factors are the main reasons. It has a better prognosis with a lower rate of recurrence. Usually nonoperative treatment. 2. Intermediate [6] It occurs between the six months and five years postoperatively. The older age, muscular laxity, and cognitive impairment are the main reasons. 3. Late dislocation [6, 7] It occurs more than five years postoperatively. It usually has a multifactorial etiology. It has a higher rate of recurrence. Frequently involves operative treatment. (c) Risk Factors 1. Patient’s [5] (a) Neuromuscular and cognitive disorders [5, 8] Muscular dystrophy, dementia, alcoholism, Parkinson, MS, etc. Muscle weakness, imbalance, and inability to comply with activity restriction (b) Age [9, 10] It is not definitely considered an independent risk factor [5]. Muscle weakness, frailty, propensity to fall, and lack of adherence to the postoperative protocol that follows the older age are the main reasons. (c) Posttraumatic/prior hip surgery and history of fracture (d) Other underlying diseases (osteonecrosis, inflammatory arthritis, DDH) [11] (e) Patient noncompliance with activity restrictions 2. Surgical (not only one cause but usually multifactorial) [5] (a) Surgical approach Although the posterior approach was considered an independent risk factor of dislocation at the past [11], the meticulous repair of the soft tissue and the use of large heads lessened the risk [10]. A meta-analysis [12] found that the dislocation rates of posterior approach with and without repair were 0.49 and 4.46%, respectively, and 8.21 times the greater relative risk for the posterior approach without soft tissue repair than with soft tissue repair [12]. Goldstein [13] et al. and Pellici [14] et al. reported decrease of dislocation rate with posterior capsule repair from 4.8 to 0.7% in 1515 patients and from 4.1 to 0%, respectively. A recent meta-analysis [15] involving 13,203 primary THAs found dislocation rates of 1.27% for trans-trochanteric, 3.23% for posterior (2.03% with capsular repair), 2.18% for anterolateral, and 0.55% for the direct lateral approach. There were however only four prospective studies that did not have sufficient power to reach statistical significance [15]. (b) Soft tissue tensioning/condition of soft tissues [4, 5] Meticulous reconstruction of posterior joint capsule and short external rotators lessened the dislocation risk [14]. Non-healing of the soft tissue following revision THA increases the risk. Trochanteric nonunion increases sixfold the risk of dislocation. Abductor deficiency [16]. (c) Restoration of offset [3, 4] Less offset limits the soft tissue tensioning and increases dislocation risk. (d) Restoration of leg length [17] (e) Component positioning [18] It is the most common cause of instability [5, 19]. Cup safe zone of abduction is 40 ± 10 and anteversion is 15–20 ± 5–10. It is also affected by the orientation of the pelvis and body position [4, 5, 20, 21]. Risk factors are low-volume surgeons, obesity, and minimal approaches [17, 19]. Femoral stem false positioning (inadequate offset, length, and/or version on the femoral side) is another reason. Uncombined version of cup and stem and the effect of pelvic tilt [22]. X-rays more suitable for inclination than anteversion measurement. Different CT protocols have been proposed but they lack standardization [4]. Femoral anteversion is easier to measure on CT by evaluating the angle between the femoral neck and the axis of posterior condyles [22], which proved that this value differs from surgeon thought by 16.8° as a mean [22]. (f) Impingement Usually femoral neck comes into contact during ROM with liner or cement, osteophyte, or heterotopic ossification creating torque and dislocation. Medial placement of femoral component and cup is another reason. Increased head/neck ratio decreases possibility. (g) Head size [18] Larger head advantages: increased head/neck ratio, avoidance of a skirted component, and increased jump distance because the head sits deeper in the shell and allows greater range of subluxation before dislocation occurs [5, 16, 23, 24]. (h) Liner profile Neutral liners increased risk than posteriorly elevated (however posteriorly elevated increase time of neck impingement and liner wear so not uniformly recommended). Oblique and lateralized. (i) Surgeon experience Higher dislocation rate was reported among surgeons who perform < 30 THAs yearly choice of implant [5]. Treatment Primary THA: first dislocation Patient assessment [5, 10] 1. History (of dislocation and surgical note) 2. Physical examination (LLD, ROM, neurovascular integrity) 3. Infection exclusion (CRP, ESR, aspiration, culture) 4. Imaging (AP X-rays, CT) to detect cup orientation, eccentric wear, the possibility of liner dissociation, osteophytes, bone quality and integrity, femoral offset, subsidence, angulation, anteversion (difficult) component geometry (including head-to-neck ratio), osteolysis, and component loosening 5. Time of dislocation is crucial for the reason/weeks or months think soft tissue tension (including muscle weakness and inadequate capsular healing and scarring), component malposition, infection, or patient noncompliance. Late dislocations (> 1 year) think stretching of the soft tissues or polyethylene wear 6. Direction of dislocation evaluated from X-rays and from the direction of relocation Closed reduction: spica With sedation to prevent damage to implant. In case of well-positioned and stable implant postreduction [3]. 6–12 weeks spica (their use based on small series [3]). Their use is extremely patient dependent [25]/even the most compliant have difficulties/probably in noncompliant patient can be considered [3, 25]. Almost two-thirds have effective treatment in this way. Indications for operative management 1. Recurrent dislocation >2 times 2. Chronic dislocation 3. Irreducible dislocation 4. Soft tissue tension 5. Impingement 6. Malposition of components (one of the primary causes) Recurrent dislocation Identify the cause to have better chance of successful management [26]. Assess the patient using the previously mentioned steps for primary DISL. Revision seems to be more effective for component malpositioning, infection, and abductor insufficiency. However, none of the available surgical procedures can uniformly solve the problem of instability [6]. In case of multifactorial cause, the treatment is less obvious.

Hip Arthroscopy Survivorship: A Population-based Study

Objectives: Recently, hip arthroscopy has been increasingly utilized to address pathology such as femoracetabular impingement and symptomatic labral tears. However, its role in advanced age and degenerative changes has not been clearly defined. The aim of this study was to examine survivorship following hip arthroscopy and identify risk factors for failure. Methods: Data from the California Office of Statewide Health Planning and Development, a mandatory statewide discharge database, was utilized to identify patients who underwent hip arthroscopy from 2000 to 2014. Exclusions included lower extremity trauma, infection, congenital deformities, malignancy, and concurrent arthroplasty. Demographic information was assessed and failure defined as conversion to total hip arthroplasty (THA). Statistically significant differences between patients requiring THA and those who did not were identified by univariate analysis. Multivariate analysis was performed to account for identified differences, and a Kaplan-Meier curve constructed to estimate 5 and 10-year survivorship. Results: After exclusions, 10,061 patients were identified with an average follow-up of 2.7 years. Five and 10-year survivorship were 90.9% and 77.9%, respectively. Patients converted to THA were older (53.1 years versus 40.1 years, p<0.001) and had more comorbidities (27.5% versus 20.1% having at least one comorbidity, p<0.001). THA patients had a higher prevalence of osteoarthritis (41.5% versus 13.24%, p<0.001) and osteochondral defects (44.0% versus 38.9%, p=0.001). On multivariate analysis, each 1-year increase in age presented a 7% increase in failure risk (OR 1.07, p<0.001). Obese patients were more likely to fail (OR 2.19, p=0.049), as were patients with osteoarthritis and osteochondral defects (OR 2.98, p<0.001 and OR 1.13, p=0.081). Patients whose surgery included removal of loose bodies or debridement were also at increased risk of failure (OR 1.58, p<0.001 and OR 1.62, p=0.001). Conclusion: Older age, obesity, and diagnoses of osteoarthritis or osteochondral defects at the time of surgery are risk factors for conversion to arthroplasty following hip arthroscopy. Table 1: Patient Demographics Total Cohort THA group Non-THA group p-value 10,061 100.00% 1,322 13.14% 8,739 86.86% Age 42.11 SD=14.07 53.07 SD=10.25 40.45 SD=13.82 <0.001 Sex Male 4,266 42.40% 540 40,85% 3,726 42.64% <0.001 Female 5,771 57.36% 772 58.40% 4,999 57.20% Unknown 24 0.24% 10 0.76% 14 0.16% Race White 7,265 72.21% 1,005 76.02% 6,260 71.63% <0.001 Black 428 4.25% 49 3,71% 379 4.34% Hispanic 1,076 10.69% 98 7.41% 978 11.19% Asian 284 2.82% 24 1.82% 260 2.98% Other 326 3.24% 23 1.74% 303 3.47% Missing 559 5.56% 123 9.30% 682 7.80% Comorbidities Hypertension 966 9.60% 228 17.25% 738 8.44% <0.001 Asthma 693 6.89% 81 6.13% 612 7.00% 0.241 Obesity 486 4.83% 92 6.96% 394 4.51% <0.001 Depression 362 3.60% 54 4.08% 308 3.52% 0.308 Diabetes mellitus 294 2.92% 51 3.86% 243 2.78% 0.030 CKD 25 0.25% 4 0.30% 21 0.24% 0.562 PVD 19 0.19% 4 0.30% 15 0.17% 0.302 CHF 9 0.09% 2 0.15% 7 0.08% 0.335 Number comorbidities None 7,951 79.03% 958 72.47% 6.993 80.02% <0.001 One 1,509 15.00% 242 18.31% 1,267 14.50% Two 478 4.75% 94 7.11% 384 4.39% Three 104 1.03% 26 1.97% 78 0.89% Four 18 0.18% 2 0.15% 16 0.18% Five 1 0.01% 0 0.00% 1 0.01% Diagnostic indications Osteoarthritis 1,706 16.96% 549 41.53% 1,157 13.24% <0.001 Osteochondral defect 3,984 39.60% 581 43.95% 3,403 38.94% 0.001 Synovitis/Tenosynovitis 1,298 12.90% 172 13.01% 1,126 12.88% 0.899 Sprains and Strains 1,659 16.49% 180 13.62% 1,479 16.92% 0.003 Other arthropathy 4,855 48.26% 5.50 41.60% 4,305 49.26% <0.001 Arthroscopy procedure Diagnostic 104 1.03% 13 0.98% 91 1.04% 0.846 Removal of loose/foreign body 584 5.80% 143 10.82% 441 5.05% <0.001 Debridement 6,795 67.54% 1,126 85.17% 5,669 64.87% <0.001 Synovectomy 2,070 20.57% 322 24.36% 1,748 20.00% <0.001 Femoroplasty 2,014 20.02% 91 6.88% 1,923 22.00% <0.001 Acetabuloplasty 1,274 12.66% 50 3.78% 1,224 14.01% <0.001 Labral repair 1,500 14.91% 58 4.39% 1,442 16.50% <0.001 Unspecified 193 1.92% 38 2.87% 155 1.77% 0.007 Figure 1. Kaplan-Meier survival curve with failure defined as conversion to total hip arthroplasty.

Redefining Zone II: Anatomy of the Flexor Digitorum Superficialis Insertion

Background: Flexor zone II is defined as the region spanning the proximal aspect of the A1 pulley to the insertion of the flexor digitorum superficialis (FDS) tendon. Descriptions of the FDS insertion are inconsistent in the literature, but zones of injury are frequently determined with reference to superficial landmarks. The purpose of this study was to describe the footprint of the FDS insertion and define its relationship to the proximal interphalangeal (PIP) skin crease. Methods: The FDS insertion on the index, middle, ring, and small fingers was dissected in 6 matched pairs of fresh-frozen cadaveric hands. A Kirschner wire was used to mark the level of the PIP skin crease on bone before measurements of the FDS footprint and its position relative to the PIP skin crease were made using digital calipers. Results: The radial and ulnar FDS slips inserted a mean distance of 3.22 mm from the distal aspect of the PIP skin crease and varied by digit. The mean distal extent of the FDS insertion was 8.29 mm. The mean length of the insertion of each FDS slip was 5.15 mm and the mean width was 1.9 mm. Conclusions: The radial and ulnar FDS slips insert on average 3.22 mm distal to the PIP skin crease and vary by digit. Knowledge of the FDS insertion is clinically relevant when differentiating between flexor zone I and zone II injuries, planning surgical approaches to the finger, and in guiding patient expectations for surgery given the variability in outcome based on zone of injury.