Component Rotation in Well-Functioning, Gap Balanced Total Knee Arthroplasty Without Navigation.

BACKGROUND: Malalignment of total knee arthroplasty (TKA) components is a potential cause of clinical failure following TKA. Since the goal of a gap balancing (GB) technique is equal flexion and extension gaps secondary to soft-tissue balancing, and not necessarily component alignment, variation in component placement may exist. Our purpose was (1) to evaluate precision of component alignment in well-functioning GB TKAs performed without the aid of navigation using computed tomographic evaluation and (2) to determine any relationship between femoral version and/or tibial torsion and TKA component positioning. METHODS: There were 93 well-functioning TKAs performed with an extension gap first GB technique with a minimum 2-year follow-up evaluated using computed tomography to assess component rotational alignment, as well as osseous femoral version and tibial torsion. Femoral and tibial rotational alignment was assessed by previously described methods. RESULTS: The mean Knee Society Score was 185.7 ± 21.7. The mean range of motion was 128.5 ± 7.8°. Femoral posterocondylar axis (relative to the transepicondylar axis) values ranged from -8.3 to 4.1° with a mean of -0.78 ± 2.7° (internal rotation). Mean tibial rotation was 17.2 ± 7.9° internal rotation relative to the tibial tubercle. No correlation was found between native femoral version and femoral component rotational alignment (Pearson's correlation coefficient, r, 0.007). Weak correlation was found between native tibial torsion and tibial component alignment (r = 0.24). CONCLUSION: Despite being only a secondary objective with the GB technique, most components evaluated were within the desired range of rotation. Alignment was not influenced by native osseous rotational geometry. LEVEL OF EVIDENCE: Level III, Retrospective Cohort Study.

Revision Total Knee Arthroplasty for Arthrofibrosis.

BACKGROUND: Arthrofibrosis after TKA is a significant cause of patient dissatisfaction. There is little evidence regarding revision arthroplasty in this patient population. The purpose of this study is to evaluate outcomes after revision TKA for arthrofibrosis. METHODS: We retrospectively reviewed 46 consecutive revision TKAs for arthrofibrosis between 2007 and 2015 with minimum 2-year follow-up. Range of motion (ROM), complication rates, and Knee Society Scores (KSS) were recorded. RESULTS: Patients were followed for a mean of 59 months. ROM and KSS significantly improved: with flexion improving from 88° to 103° and extension improving from 11° to 3° (P < .001). There was not a relationship between patient or surgical factors and outcomes in this study. The rate of complications was 28.2% with a 17.4% reoperation rate. CONCLUSION: While revision for arthrofibrosis after TKA can be associated with significant improvements in ROM and KSS, caution is advised given high rates of revisions, reoperations, and complications. Thirty percent of patients in this series had a decrease in one or more component of the KSS or a net decrease in arc of motion after revision surgery.

Radiographic Changes in Nonoperative Contralateral Knee After Unilateral Total Knee Arthroplasty.

BACKGROUND: Some patients perceive symptomatic improvement in the contralateral knee after unilateral total knee arthroplasty (TKA). This so-called "splinting effect" has been observed but has not been radiographically evaluated. METHODS: A retrospective review of patients with bilateral knee osteoarthritis treated with unilateral TKA was performed. Patients were subcategorized into 2 groups based on whether contralateral TKA was performed within the 2-year period. Contralateral radiographic measurements were performed. RESULTS: Forty-four of 203 patients had contralateral TKA performed within 2 years. Preoperative parameters were significantly worse in the bilateral group. By 6 weeks postoperatively, mechanical axis plumbline improved approximately 1°, with more change in those patients with preoperative varus alignment. Larger delta changes were also present in bilateral group preoperative to 1-year radiographs for tibiofemoral angle and joint space widening. CONCLUSION: In patients with bilateral knee osteoarthritis who undergo unilateral TKA, a splinting effect may be present and measurable radiographically with improvement of contralateral mechanical axis plumbline. Further research is necessary to determine whether this improvement may delay contralateral TKA implantation.

What is the Long-term Economic Societal Effect of Periprosthetic Infections After THA? A Markov Analysis.

BACKGROUND: Current estimates for the direct costs of a single episode of care for periprosthetic joint infection (PJI) after THA are approximately USD 100,000. These estimates do not account for the costs of failed treatments and do not include indirect costs such as lost wages. QUESTIONS/PURPOSES: The goal of this study was to estimate the long-term economic effect to society (direct and indirect costs) of a PJI after THA treated with contemporary standards of care in a hypothetical patient of working age (three scenarios, age 55, 60, and 65 years). METHODS: We created a state-transition Markov model with health states defined by surgical treatment options including irrigation and débridement with modular exchange, single-stage revision, and two-stage revision. Reoperation rates attributable to septic and aseptic failure modes and indirect and direct costs were calculated estimates garnered via multiple systematic reviews of peer-reviewed orthopaedic and infectious disease journals and Medicare reimbursement data. We conducted an analysis over a hypothetical patient's lifetime from the societal perspective with costs discounted by 3% annually. We conducted sensitivity analysis to delineate the effects of uncertainty attributable to input variables. RESULTS: The model found a base case cost of USD 390,806 per 65-year-old patient with an infected THA. One-way sensitivity analysis gives a range of USD 389,307 (65-year-old with a 3% reinfection rate) and USD 474,004 (55-year-old with a 12% reinfection rate). Indirect costs such as lost wages make up a considerable portion of the costs and increase considerably as age at the time of infection decreases. CONCLUSIONS: The results of this study show that the overall treatment of a periprosthetic infection after a THA is markedly more expensive to society than previously estimated when accounting for the considerable failure rates of current treatment options and including indirect costs. These overall costs, combined with a large projected increase in THAs and a steady state of septic failures, should be taken into account when considering the total cost of THA. Further research is needed to adequately compare the clinical and economic effectiveness of alternative treatment pathways. LEVEL OF EVIDENCE: Level II, economic and decision analysis.

The Basics of the Sunshine Act: How It Pertains to the Practicing Orthopaedic Surgeon.

The Physician Payments Sunshine Act is a disclosure law requiring all drug, medical device, and biologics companies to report transfers of value to physicians and teaching hospitals. It was passed into law in 2010 as part of the Affordable Care Act. The first set of data was released via an online public database on September 30, 2014, with subsequent annual reports to come. Three categories of payments are recorded: general payments, ownership interests, and research payments. With few exceptions, any transfer of value greater than $10 is reported. The first dataset of 4.4 million payments totaling more than $3.5 billion was released amidst controversy and technical problems. Identified data constituted $1.3 billion in transfer payments; de-identified data constituted $2.2 billion in payments. Data regarding an additional $1.1 billion in payments were not published, in part because of unresolved disputes. The largest amount of funding went to research payments. The highest proportion of general payments went to licensing and royalty payments. Orthopaedic surgeons comprised 3.5% of the physicians represented, and they were responsible for more than 20% of total payments. The full impact of the Sunshine Act will not be clear until several years after its implementation.

Does the addition of a nerve wrap to a motor nerve repair affect motor outcomes?

The purpose of this study was to evaluate the effect of wrapping bioabsorbable nerve conduit around primary suture repair on motor nerve regeneration in a rat model. Forty rats were randomly divided into two experimental groups according to the type of repair of the rat sciatic nerve: group I had primary suture repair; group II had primary suture repair and bioabsorbable collagen nerve conduit (NeuraGen® 1.5 mm, Integra LifeSciences Corp., Plainsboro, NJ) wrapped around the repair. At 12 weeks, no significant differences in the percentage of recovery between the two groups were observed with respect to compound muscle action potentials, isometric muscle force, and muscle weight (P = 0.816, P = 0.698, P = 0.861, respectively). Histomorphometric analysis as compared to the non-operative sites was also not significantly different between the two groups in terms of number of myelinated axons, myelinated fiber area, and nerve fiber density (P = 0.368, P = 0.968, P = 0.071, respectively). Perineural scar tissue formation was greater in primary suture repair group (0.36 ± 0.15) than in primary repair plus conduit wrapping group (0.17 ± 0.08). This difference was statistically significant (P < 0.001). Wrapping bioabsorbable nerve conduit around primary nerve repair can decrease perineural scar tissue formation. Although the scar-decreasing effect of bioabsorbable nerve wrap does not translate into better motor nerve recovery in this study, it might have an effect on the functional outcome in humans where scar formation is much more evident than in rats.

Learning curve of robotic-assisted microvascular anastomosis in the rat.

We hypothesized that the learning plateau and learning rate of robotic-assisted microvascular anastomosis could be estimated statistically using curve-fitting method. Three surgeons with various microsurgical experiences performed 20 microsurgical anastomoses of the rat femoral artery using the da Vinci robotic system (Intuitive Surgical, Inc., Sunnyvale, CA). We evaluated the anastomosis time, patency rate, and quality of anastomosis. Objective structured assessment of technical skills (OSATS) score which is introduced to assess surgical dexterity was also measured. The average starting anastomosis time was 101 ± 30 minutes, and the estimated mean learning plateau was 33 ± 15 minutes. The estimated mean learning rate for anastomosis time was 22 ± 5 trials and the estimated mean learning rate for OSATS score was 8 ± 1 trials. Overall patency rate was 90 ± 5%. Anastomosis patency correlated with OSATS score and quality of anastomosis rather than anastomosis time. Important aspects of learning curve can be estimated by fitting inverse curves for robotic-assisted microvascular anastomosis. As anastomosis time does not necessarily correlate with the patency rate, OSATS score might be a valuable tool to evaluate surgeons during training for this complicated surgical task.

Meralgia paresthetica: relation to obesity, advanced age, and diabetes mellitus.

OBJECTIVE: To determine the incidence of meralgia paresthetica (MP) and its relationship to diabetes mellitus (DM) and obesity. METHODS: A population-based study was performed within Olmstead County Minnesota, from January 1, 1990, to December 31, 1999. MP incidence and its association with age, gender, body mass index (BMI), and DM were reviewed. RESULTS: A total of 262 patients with MP, 262 normal controls, and 262 BMI-matched normal controls with mean age of 50 years were identified (51% men). The age- and sex-adjusted incidence of MP was 32.6 per 100,000 patient years, whereas the incidence of MP in people with DM was 247 per 100,000 patient years, 7 times the occurrence of MP in the general population. Of the patients with MP, 28% had DM vs 17% of BMI-matched controls and the majority of people with MP developed DM after the diagnosis of MP. Patients with MP are 2 times more likely to develop DM (odds ratio 2, 95% confidence interval 1.3-3.0, p = 0.0027). The mean BMI of patients with MP (30.1 kg/m(2), obese class I) was significantly higher than that of age- and gender-matched controls (27.3 kg/m(2), overweight). MP incidence increased 12.9 per 100,000 patient years in the hemidecade study period with an associated increase in both BMI (2.2 kg/m(2)) and average age (3 years). CONCLUSIONS: MP is a frequent painful neuropathy associated with obesity, advancing age, and DM. The incidence rate of MP is predicted to increase as these demographics increase in world populations. Because MP associates with DM beyond weight- and age-matched controls, more aggressive counseling of these patients in prevention of DM may be warranted.

Patterns of intraneural ganglion cyst descent.

On the basis of the principles of the unifying articular theory, predictable patterns of proximal ascent have been described for fibular (peroneal) and tibial intraneural ganglion cysts in the knee region. The mechanism underlying distal descent into the terminal branches of the fibular and tibial nerves has not been previously elucidated. The purpose of this study was to demonstrate if and when cyst descent distal to the articular branch-joint connection occurs in intraneural ganglion cysts to understand directionality of intraneural cyst propagation. In Part I, the clinical records and MRIs of 20 consecutive patients treated at our institution for intraneural ganglion cysts (18 fibular and two tibial) arising from the superior tibiofibular joint were retrospectively analyzed. These patients underwent cyst decompression and disconnection of the articular branch. Five of these patients developed symptomatic cyst recurrence after cyst decompression without articular branch disconnection which was done elsewhere prior to our intervention. In Part II, five additional patients with intraneural ganglion cysts (three fibular and two tibial) treated at other institutions without disconnection of the articular branch were compared. These patients in Parts I and II demonstrated ascent of intraneural cyst to differing degrees (12 had evidence of sciatic nerve cross-over). In addition, all of these patients demonstrated previously unrecognized MRI evidence of intraneural cyst extending distally below the level of the articular branch to the joint of origin: cyst within the proximal most portions of the deep fibular and superficial fibular branches in fibular intraneural ganglion cysts and descending tibial branches in tibial intraneural ganglion cysts. The patients in Part I had complete resolution of their cysts at follow-up MRI examination 1 year postoperatively. The patients in Part II had intraneural recurrences postoperatively within the articular branch, the parent nerve, and the terminal branches, although in three cases they were subclinical. The authors demonstrate that cyst descent distal to the take-off of the articular branch to the joint of origin occurs regularly in patients with fibular and tibial intraneural ganglion cysts. The authors believe that parent terminal branch descent follows ascent up the articular branch from an affected joint of origin. This mechanism for bidirectional flow explains cyst within terminal branches of the fibular and tibial nerves and is dependent on pressure fluxes and resistances. This new pattern is consistent with principles previously described in a unified (articular) theory, is generalizable to other intraneural ganglion cysts arising from joints, and has important implications for pathogenesis and treatment of these intraneural cysts.