The implications of mechanical alignment on soft tissue balancing in total knee arthroplasty.

PURPOSE: We hypothesized that the individual bone geometry is the most important variable to achieve acceptable soft tissue balancing during total knee arthroplasty. METHODS: Long-standing 3-foot films and computer navigation data from 90 patients with varus (n = 45) or valgus deformity (n = 45) were utilized who underwent navigated total knee arthroplasty. Mean age was 65 ± 8 years with 50 women and 40 men. Hip-knee-ankle angle (HKA) was measured and ranged from 23° varus to 21.5° of valgus. Three additional measurements were made: lateral distal femoral angle (DFA), the intraarticular angle (IAA), and the medial proximal tibial angle (PTA). Intra-operative computer navigation data were obtained. Knees were then stressed with both a maximum varus/valgus moment in 10° flexion. Values were compared with the angle measurements of 3-foot films. Maximum varus/valgus measurements were correlated with HKA for both varus and valgus knees. RESULTS: Varus knees: Mean HKA measured 9° ± 5°, and the maximum varus stress measured intraoperatively was 12° ± 4°. The mean DFA, PTA, and IAA were 88° ± 2.5°, 84° ± 3.4°, and 4.5° ± 2.5°, respectively. If the HKA was <10°, the deformity was correctable in (16/26) 61 % of cases. Positive correlation exists between the HKA, and maximal varus stress obtained intraoperatively (r = 0.75, p < 0.0001). IAA correlated with increasing HKA (r = 0.80, p < 0.0001). Mean IAA was significantly greater in the varus than valgus group (4.5 ± 2.6 vs 3.2 ± 2.4, respectively, p = 0.01). Valgus knees: Mean HKA measured was 9.4° ± 4°. The mean DFA, PTA, and IAA were 83° ± 2°, 89.5° ± 2°, and 3.2° ± 2.4°, respectively. If the HKA was more than 10°, maximal varus stress of the knee was able to correct the valgus deformity (15/22) 68 % of the time. If the HKA was <10°, the deformity was correctable in (21/23) 91 % of cases. Positive correlation exists between the HKA and maximal valgus stress examination (r = 0.74, p < 0.0001). There was a positive correlation of IAA with increasing HKA (r = 0.61, p < 0.0001). Mean flexion contracture for varus knees was 6.3° ± 6.9° compared with 0.8° ± 7.6° in the valgus group (p = 0.0004). CONCLUSION: These data suggest that soft tissues play more of a role in the varus knee deformity than they do in the valgus knee and that the bony contribution may be the main contributing factor to the overall deformity of the valgus knee. LEVEL OF EVIDENCE: IV.

Short Term Outcomes of a Hydroxyapatite Coated Metal Backed Patella.

We retrospectively evaluated the records and radiographs of 101 knees with a hydroxyapatite coated metal backed patella (HAP) and 50 knees with a cemented polyethylene patella (CP) with minimum two year clinical follow up. There were no patellar revisions during the study period. Patients in both the HAP and CP groups had similar clinical outcomes at final follow-up. Forty-five percent of patients in the HAP group had 1-2mm areas of decreased trabecular bone density around the pegs, which were not observed in the CP group, and may represent stress shielding. This uncemented HAP component has satisfactory early clinical outcomes, but long-term follow up is necessary to determine the durability of this implant.

Hemiarthroplasty of the distal humerus for acute and chronic complex intra-articular injuries.

BACKGROUND: Comminuted intra-articular distal humeral fractures represent a challenging upper extremity injury. This study reviews clinical and radiographic results in patients with distal humeral hemiarthroplasty (DHH). METHODS: DHH with the Latitude prosthesis (Tornier, Saint-Ismier, France) was performed in 8 patients (mean age, 64 years; age range, 33-75 years) for unreconstructible fractures of the distal humerus or salvage of failed internal fixation. Clinical outcomes were assessed with the American Shoulder and Elbow Surgeons elbow instrument; Mayo Elbow Performance Index; and Disabilities of the Arm, Shoulder and Hand questionnaire at a mean of 36 months. Radiologic assessment included radiographs and computed tomography to evaluate olecranon wear and densitometry (dual-energy x-ray absorptiometry). Range of motion, pain, and elbow satisfaction were recorded, and descriptive statistics were used for analysis. RESULTS: Seven patients were available to participate in the follow-up examination. Acute cases (5 patients) scored better than salvage cases (2 patients) on the Mayo Elbow Performance Score (80 points [range, 67-95 points] and 65 points [range, 50-80 points], respectively) and Disabilities of the Arm, Shoulder and Hand score (31 points [range, 2.5-68 points] and 39 points [range, 17-62 points], respectively). The mean arc of elbow flexion and extension was 96° (range, 70°-130°), with mean flexion of 120° (range, 90°-135°) and a mean extension loss of 19° (range, 5°-30°). The mean arc of forearm rotation was 160° (range, 140°-180°). Reoperation was required in 4 patients because of painful retained hardware. Five patients reported pain with activities of daily living. CONCLUSION: DHH should be used with caution until such time as longer-term outcome studies are able to show the efficacy of this procedure.

A radiographic and clinical comparison of reamer-irrigator-aspirator versus iliac crest bone graft in ankle arthrodesis.

PURPOSE: We evaluated radiographic fusion at follow-up and complication rates in patients who had either iliac crest (ICBG) or femoral reamer-irrigator-aspirator (RIA) bone graft for tibiotalar fusion. METHODS: We retrospectively reviewed charts and radiographs of all patients who had a tibiotalar fusion from August 2007 to February 2011. Records were analysed for patient demographics, complications, and clinical symptoms. Radiographs were reviewed in sequential order by two fellowship-trained foot and ankle surgeons and one orthopaedic surgeon who specialises in foot and ankle surgery to determine radiographic fusion at routine follow-up. Patients were contacted to determine current visual analog scores (VAS) at their graft site. RESULTS: Mean patient age was 49.4 ± 12.1 years in the RIA group and 49.3 ± 15.4 years in the ICBG group (p = .97). Pre-operative characteristics showed no significant differences between groups. The ICBG group had significantly more nonunions than the RIA group (six vs. one, p = 0.04). Two patients in the ICBG had chronic pain at their graft site based on their VAS score; there were none in the RIA group. Radiographic fusion at follow-up was similar between groups, with no significant difference (12.48 ± 3.85 weeks vs.12.21 ± 3.19 weeks, p = .80). CONCLUSIONS: There was a significantly higher nonunion rate in the ICBG group, but both groups had a solid radiographic bony fusion at similar follow-up time points. Our results suggest RIA bone graft is a viable alternative to ICBG for tibiotalar fusion.

Antimicrobial susceptibility of Propionibacterium acnes isolates from shoulder surgery.

Orthopedic surgeons at our institution have noticed an increase in the number of infections due to Propionibacterium acnes, especially following operations on the shoulder. We collected P. acnes isolates from our hospital microbiology laboratory for 1 year and performed antimicrobial susceptibility testing on 28 strains from the shoulder. Antibiotics with the lowest MIC values against P. acnes (MIC50 and MIC90) included penicillin G (0.006, 0.125), cephalothin (0.047 and 0.094), and ceftriaxone (0.016, 0.045), while others also showed activity. Strains resistant to clindamycin were noted.

Bilateral acetabular fractures in an adolescent after low-energy trauma.

BACKGROUND: Pediatric pelvic fractures are rare, accounting for approximately 2.4% to 5.5% of annual admissions at large level I trauma centers. An acetabular fracture is involved in only about 1% to 15% of these cases and is almost exclusively caused by a high-energy trauma. METHODS: This is a report of an otherwise healthy 15-year-old male adolescent who sustained a nondisplaced bilateral anterior column and wall acetabular fracture after a low-energy mechanism during a hockey game. The patient was managed nonoperatively with non-weight-bearing restrictions and had complete resolution of his symptoms by 10 weeks. RESULTS: This case shows that a low-energy mechanism can create significant bilateral acetabular fractures in the immature skeleton. CONCLUSIONS: The presented case may represent an underdiagnosed cause of hip and groin pain in the adolescent patient/athlete when initial radiographs appear normal.

Hemolysis as a clinical marker for propionibacterium acnes orthopedic infection.

Determining if a Propionibacterium acnes culture is a true infection or a contaminant remains a challenge. We conducted a study to distinguish between a true infection and a contaminated culture based on the P acnes hemolytic phenotype and clinical presentation. All P acnes strains were from orthopedic patients who had undergone arthroplasty or nonarthroplasty shoulder procedures. Hemolysis was determined according to P acnes growth on brucella blood agar plates after 48 to 72 hours. Each patient record that corresponded to the obtained P acnes strains was retrospectively reviewed for clinical data. An orthopedic surgeon involved in the care of the patients, but blinded to the hemolytic status of the bacteria, classified these infections as definite, likely, or unlikely. Of the 22 P acnes strains, 13 were hemolytic, and 9 were nonhemolytic. Of the 13 hemolytic strains, 10 were definite infections; only 3 of the 9 nonhemolytic strains were definite infections. Mean (SD) C-reactive protein level was significantly higher (P = .03) in the hemolytic group, 16 (11) mg/mL, than in the nonhemolytic group, 7.9 (10) mg/mL. A hemolytic phenotype of P acnes may represent a more pathogenic strain of bacteria, and may be more likely to be found in patients with a definite infection with P acnes rather than a contaminated culture.

Biomechanical comparison of femoral fixation devices for anterior cruciate ligament reconstruction using a novel testing method.

BACKGROUND: A novel biomechanical test method was implemented to compare the mechanical performance of two femoral fixation anchors (AperFix(r), Cayenne Medical, Scottsdale, AZ, USA or the AppianFx(r), KFx Medical, Carlsbad, CA, USA) that were utilized in anterior cruciate ligament reconstruction. METHODS: Anterior cruciate ligament reconstructions were performed in 20 porcine femurs by using bovine extensor tendon grafts secured with 9 mm femoral anchors (AperFix(r) or AppianFx(r)). 10 specimens were tested for each anchor type. Infrared position sensors determined the repair construct displacements during conditioning (20 cycles at 5-50 N at 0.25 Hz), cyclic loading (1500 cycles at 50-200 N at 1 Hz), and ultimate loading (150 mm/min). Outcomes included tendon elongation, anchor displacement, stiffness, maximum load, yield load, and load at 5mm of anchor displacement. It was hypothesized that there would be no differences in the outcomes of these two devices. Independent measure t-tests compared the performance of the devices (p<0.05). FINDINGS: The performance of the two anchors was comparable during the cyclic loading. During ultimate loading, a statistically higher yield load (p<0.01) and a load at 5mm of anchor displacement (p<0.01) were demonstrated for the AppianFx(r) as compared to AperFix(r). Maximum load and stiffness were not significantly different. INTERPRETATION: Given the good clinical track record of the AperFix(r), the comparable, and in some cases superior, the biomechanical data presented here for the AppianFx(r) are encouraging for their clinical implementation. This study also introduced a novel test method that directly tracks the relevant construct displacements during cyclic and ultimate loading tests of the anterior cruciate ligament reconstructions.

Brace treatment resulting in overcorrection of adolescent idiopathic scoliosis.

Brace treatment for idiopathic scoliosis in skeletally immature children is the only effective nonoperative modality for the control of curve progression. The Charleston bending brace is a custom-molded spinal orthosis that holds the patient in a completely corrected or overcorrected position while worn at night. A 9-year-old girl presented with 10° right upper thoracic and 7° left lower thoracic curves and was Risser sign 0. Nighttime treatment with a Charleston bending brace was initiated when the left lower thoracic curve progressed to 19°. After 27 months of nighttime brace wear, the lower thoracic curve was 21° to the right. Further investigation, including magnetic resonance imaging of the spine, failed to diagnose an identifiable explanation for this atypical occurrence. Conservative treatment may improve radiographic and cosmetic appearance. Overcorrection of the curve, although not likely, is possible when part-time or nighttime bracing is implemented as a means of conservative management.

Ceramic-on-ceramic failure secondary to head-neck taper mismatch.

We report a case of catastrophic failure of ceramic-on-ceramic total hip arthroplasty without precipitating event or trauma. The patient was a 64-year-old woman who had degenerative osteoarthritis and underwent the index primary total hip arthroplasty 3 years earlier. Intraoperative findings included an intact ceramic femoral head, a slightly damaged ceramic liner insert, diffuse metallosis, and excessive wear of the trunnion of the stem. After removal of the metallic debris, excision of metalloid tissue, and copious lavage of the joint, the prosthesis was revised to a modular revision system. Although previous operative reports had been reviewed before surgery, there was no indication of a head-neck taper mismatch. Only after revision surgery was performed, and high suspicion arose, were previous implant records analyzed and the mismatch identified.

Lymphangioleiomyomatosis: A review.

Lymphangioleiomyomatosis (LAM) is a rare disease, of unknown etiology, affecting women almost exclusively. Microscopically, LAM consists of a diffuse proliferation of smooth muscle cells. LAM can occur without evidence of other disease (sporadic LAM) or in conjunction with tuberous sclerosis complex (TSC). TSC is an autosomal dominant tumor suppressor gene syndrome characterized by seizures, mental retardation, and tumors in the brain, heart, skin, and kidney. LAM commonly presents with progressive breathlessness or with recurrent pneumothorax, chylothorax, or sudden abdominal hemorrhage. Computed tomography (CT) scans show numerous thin-walled cysts throughout the lungs, abdominal angiomyolipomas, and lymphangioleiomyomas. No effective treatment currently exists for this progressive disorder. The prevalence of lymphangioleiomyomatosis is probably underestimated based on its clinical latency and the absence of specific laboratory tests. With the utilization of international LAM data registries the "classical" picture of the disorder appears to be evolving as a larger number of patients are evaluated. An increased awareness of LAM and its common clinical presentation may advance the development of new therapeutic strategies and reduce the number of mistakenly diagnosed patients.