Shoulder Adhesive Capsulitis Prior to Total Knee Arthroplasty is Associated With Increased Rates of Postoperative Stiffness Requiring Manipulation Under Anesthesia and Arthroscopic Lysis of Adhesions.

BACKGROUND: Arthrofibrosis following total knee arthroplasty (TKA) and adhesive capsulitis (AC) of the shoulder develop via a similar pathologic process. The purpose of this study was to examine the relationship between these two conditions. METHODS: This was a retrospective cohort study using a large nationwide claims database. Patients who had a history of shoulder AC prior to TKA were compared to TKA patients who did not have AC history comparing rates of postoperative stiffness, manipulation under anesthesia (MUA), arthroscopic lysis of adhesions (LOAs), and revision arthroplasty at postoperative timepoints (3 months, 6 months, 1 year, and 2 years). RESULTS: Within 3 months, 6 months, 1 year, and 2 years of their TKAs, patients who had a history of AC prior to TKA were significantly more likely to experience stiffness (OR [odds ratio] = 1.29, 1.28, 1.32, and 1.36, respectively) and LOAs (OR = 6.78, 3.65, 2.99, and 2.81, respectively). They also showed increased risk of MUA within 6 months, 1 year, and 2 years (OR = 1.15, 1.15, and 1.16, respectively) of their TKAs. Patients having a preoperative diagnosis of AC did not have an increased risk of undergoing revision surgery 1 year or 2 years after their TKAs (P > .05). CONCLUSIONS: Patients diagnosed with AC prior to TKA experience higher rates of postoperative stiffness, resulting in additional interventions such as MUA and LOAs. These findings identify a particularly high-risk patient population that may benefit from additional interventions prior to and following TKA. LEVEL OF EVIDENCE: This is a level III prognostic study.

Changes in load distribution in the knee after opening-wedge or closing-wedge high tibial osteotomy.

The treatment of unicompartmental osteoarthritis of the knee by high tibial osteotomy has been carried out by closing-wedge osteotomy. The advantages for opening-wedge osteotomy are ease of procedure and improved correction with comparable short-term to midterm results. It is not known how the opening-wedge high tibial osteotomy procedure alters the load distribution between the medial and lateral compartments of the knee. The current biomechanical study investigated opening-wedge vs closing-wedge osteotomies in 5 pairs of cadaver knees. The results showed that at 5 degrees osteotomy, the closing-wedge provided superior results of load transfer from medial to lateral compartment than that seen with opening-wedge, but at 10 degrees osteotomy, there was no significant difference in load transfer in the knee compartments between the 2 surgery modes.

A biomechanical study of bankart lesion fixation - biodegradable ArthroRivet tack vs. suture repair.

Bioabsorbable fixation is commonly used in soft tissue procedures performed in the shoulder. ArthroRivettrade mark tacks (referred to as rivets here), made from a copolymer of 82% poly-L-lactic acid and 18% polyglycolic acid, were developed for the Bankart procedure. Although a previous in vivo study demonstrated favorable comparison of the fixation strength and absorption characteristics of this device with that of polyglyconate bioabsorbable tacks, there have been no published biomechanical studies of this rivet in the shoulder. Fourteen shoulders were harvested from fresh-frozen cadavers of average age 74 years (46-89). Biomechanical testing was performed by measuring the energy, or work, required to anteriorly displace the humeral head 6 mm from the glenoid. Each shoulder was tested intact, vented, and before and after repair of a simulated Bankart lesion at 0, 45, and 90 degrees of abduction with and without maximal external rotation. Overall, the average work required ranged from 54.7 N-mm to 178.27 N-mm. Although the biomechanical performance of the rivet, based on resistance to anterior displacement of the humeral head, was indistinguishable from that of the suture repair, the statistical power of the test was low due to the large variance in the cadaver specimens. The results, in general, correlated well with those of previously published studies, suggesting the suitability of the bioabsorbable rivet for use in Bankart repair.

Ethics and constitutional government.

The term ethics refers to a set of principles that govern acceptable, proper conduct. Attacks on the Constitution of the United States pose the most serious breach of ethics today. Our country was founded as a republic, not as a democracy. Our Founding Fathers' main concern was to protect citizens from the power of the federal government, so constitutionally, the central government has little or no authority over individual citizens except on federal property. One of the major problems today is the fact that we now have professional politicians. This is due in large part to the lure of financial gain from countless special interest groups. This would change under constitutional law because the federal budget would decrease drastically. Article 1 states that all legislative power is vested in Congress. Congress has only 18 enumerated powers, and almost half of these pertain to defense of the country. Many of our current problems are due to regulatory agencies that have become independent fiefdoms with unconstitutional legislative, as well as executive and judicial, powers. The regulatory agency most relevant to medicine, both clinical care and research, is the FDA. It is now obvious that its basic structure needs to be changed or abolished because its actions are identical to those inherent in authoritarian systems. Constructive change could come from Congress, but it would be most desirable if the Supreme Court would take the lead and reestablish the authority of the Constitution as the Supreme Law of the Land. The FDA's function could be limited to the determination of safety, but preferably its mission would be altered to that of product certification. Defenders of the current system claim that such a drastic change would be too dangerous and their prime example is thalidomide. But it is now known that the market has already solved that problem prior to the government-imposed sanctions. Realistically, market forces and their ramifications, including our legal system, provide the most effective methods of protecting the public from harmful drugs and devices. Fortunately, a model for miracles is available. It is New Zealand, which had become increasingly socialistic after WW II. As a result, they had become noncompetitive, and with the formation of the European Union, they lost their major market exports. In order to survive they made some astounding changes in the mid-1980s. They studied every agency that depended on government funding and transferred much of this work over to the private sector. They turned the remaining agencies into profit-making enterprises. These agencies had cost the government about $1 billion/year. Now, they produce about $1 billion in revenue and taxes. Without question, a return to constitutional government would be an invigorating stimulus to bioengineering research in the future. It would flourish. The eminence of this country did not develop from a strong central government. It is due to its absence, but we are rapidly reaching a point of no return.

A biomechanical study of simulated femoral neck fracture fixation by cannulated screws: effects of placement angle and number of screws.

The angle of placement of hip screws to fix femoral neck fractures is still a controversial subject, and it must be addressed. In the study reported here, we compared the relative stiffness of fixation of simulated Pauwels type III femoral neck fractures fixed with either 2 or 3 cannulated screws implanted at 135 degrees, 145 degrees, and 150 degrees. Each femur was fixed with 2 or 3 cannulated screws and tested under axial loading and anteroposterior (AP) bending. Then each femur was fatigued to 1000 cycles and tested to failure. Fourteen femurs were tested. Results showed that axial stiffness values were not statistically different at different angles. AP bending stiffness of the high-angle (150 degrees) construct was significantly higher than that of either of the other 2 constructs (for 2 screws only). Two-screw fixation appears to be adequate; adding a third screw may not be necessary.

Assessment of immunologic mechanisms for flare reactions to Synvisc.

Intraarticular injection of Synvisc for treatment of knee pain sometimes results in an acute local reaction (flare). We tested the hypothesis that the flare was a Type-1 hypersensitivity reaction as manifested by the presence of Synvisc antibodies in the synovial fluid and serum and by an increase in the concentration of the mast-cell enzyme tryptase in the synovial fluid. Our second objective was to determine whether the ratio of CD4+ to CD8+ lymphocytes in the synovial fluid was increased, as would be expected in a Type-4 hypersensitivity reaction. The study population was a prospective, consecutive series of 16 patients who had a flare, and 20 control patients. We found no differences in product-specific antibodies in the synovial fluid or serum between patients with flares and patients without flares. The mean tryptase level in the synovial fluid of patients with flares, 3.8 +/- 0.8 microg/L, was not different from the corresponding level in the control patients. The CD4+/CD8+ ratio in the synovial fluid was more than eight times greater in patients with flares. Flares that sometimes occur after treatment with Synvisc are probably not Type-1 (antibody-mediated) hypersensitivity reactions, but may be Type-4 (cell-mediated) hypersensitivity reactions.

Percutaneous plate fixation of comminuted ulnar fractures.

The superficial location of ulnar fractures allows minimally invasive insertion of percutaneous plates, which improves stability and creates a friendly healing environment.

External suction drainage in primary total joint arthroplasties.

We compared a novel external suction drainage (ESD) system with a conventional internal suction drainage (ISD) system in patients undergoing primary total hip or knee arthroplasties. Forty-two consecutive patients were studied: 22 who received an ISD system and 20 who received the ESD system. Drainage volume was measured, standardized questionnaires were used to assess patient comfort and response to drain removal, and number of complications were recorded. Significantly less drainage, less pain, and fewer complications occurred in patients treated with the ESD system (P<.05 for each endpoint). Results showed that ESD has advantages over ISD in primary total hip and knee arthroplasties.

Distal tibiofibular syndesmosis fixation: a cadaveric, simulated fracture stabilization study comparing bioabsorbable and metallic single screw fixation.

Metal screws that are used for ruptured tibiofibular syndesmosis repair are often removed within 3 months of placement, suggesting the utility of bioabsorbable screws. A biomechanical study was performed to compare fixation of a simulated syndesmosis separation with a 5-mm oriented copolymer bioabsorbable (82:18 poly-L-lactic acid/poly-glycolic acid) versus a stainless steel screw. Eight pairs of cadaveric lower-leg specimens were cleaned and a pronation external rotation-type injury was created in each. The syndesmosis was fixed with a single, tricortical bioabsorbable screw in 1 ankle and a metal screw in the contralateral ankle (matched pairs). Sequential testing of the specimens showed that torsional stiffness of the fixed, relative to intact, specimens was nearly equivalent (0.730 +/- 0.260 for copolymer, 0.770 +/- 0.300 for stainless steel; P = .401). Application of 1000 cycles of axial load (90 to 900 N) resulted in a significant decrease ( P < .0001) in axial stiffness for each fixation method, but the relative decrease was equivalent for both ( P = .211). Failure torque (17.8 +/- 8.3 N.m copolymer, 21.0 +/- 11.5 N.m stainless steel; P = .238) and angle of rotation at failure (47.9 +/- 13.6 degrees copolymer, 42.0 +/- 11.5 degrees stainless steel; P = .199) were also nearly equivalent. It appears that the 5.0-mm diameter copolymer screw is biomechanically equivalent to the 5.0-mm diameter stainless steel screw for repair of syndesmosis disruption.

A biomechanical study of unilateral posterior atlantoaxial transarticular screw fixation.

The purpose of this study was to investigate the fixation of C1-C2 instability with the use of a unilateral screw. Transarticular screw placement across C1-C2 may be contra-indicated in up to 20% of specimens on at least one side because of anatomic variations or other pathological processes. Hence the current study looks into unilateral screw fixation of C1- C2 instability. Eight cervical spine specimens, C1 through C5, were harvested from fresh human cadavers (4 male and 4 female) of average age 67 years (54-80). C1 and C2-C5 vertebrae were potted to allow motion only at the C1-C2 articulation. Cutting the transverse ligament on both sides of the odontoid and the tectorial membrane destabilized the specimens. Transarticular screw fixation of C1-C2 was performed in a manner similar to the technique described by Magerl. The stability was tested after fixation with one transarticular screw together with a posterior graft and wire. Placement of the screw was randomized, resulting in half the specimens receiving screws on the right side and the remaining half on the left side. The stiffness of the C1-C2 articulation was tested in rotation, lateral bending, flexion, and anterior translation in random order. The rotational stiffness was 1.44 +/- 0.44 N-m/deg, while lateral bending stiffness values were 2.33 +/- 1.14 N-m/mm (right bending) and 2.81 +/- 1.36 N-m/mm (left bending). The stiffness value in flexion was 0.813 +/- 0.189 N-m/mm and in translation 67.1 +/- 25.1 N/m. It was found that stability after unilateral transarticular screw fixation was less than that previously reported after bilateral transarticular screw fixation, but similar to that found with modified Brooks posterior wiring, which has been shown to provide better stability than other posterior wiring methods, and fusion rates of 96% have been reported. We concluded that C1-C2 unilateral posterior transarticular screw fixation with supplemental posterior graft and wiring would confer adequate stability in cases where bilateral screw placement is contraindicated.

Increased intercellular communication through gap junctions may contribute to progression of osteoarthritis.

Our aim was to support the hypothesis of a specific association between gap junctions in synovial tissue and the presence of osteoarthritis, as evidenced by differences between osteoarthritis and non-osteoarthritis synovia in the number of gap junctions, the amount of gap-junction protein, and the amount of enzymatic activity produced through a pathway mediated by gap-junction intercellular communication. An average of 4.41 gap junctions were found per 100 cells counted in the osteoarthritis synovia, compared with 1.00 in the controls. The amount of the gap-junction protein connexin 43 in synovial lining cells was approximately 50% greater in patients with osteoarthritis. Synovial lining cells from patients with osteoarthritis produced matrix metalloproteinases constitutively and, at higher levels, in response to stimulation by interleukin-1 beta. In both cases, intercellular communication through gap junctions was shown to be critical to the ability of the cells to secrete matrix metalloproteinases. Overall, the results indicated that gap junctions between synovial lining cells were altered significantly in patients with osteoarthritis, as a consequence of the disease process or as part of the causal chain. In either case, gap junctions seem to be a rational therapeutic target.

IL-1beta-induced production of metalloproteinases by synovial cells depends on gap junction conductance.

Synovial cells can form networks connected by gap junctions. The purpose of this study was to obtain evidence for a necessary role of gap junction intercellular communication in protein secretion by synovial cells. We developed a novel assay to measure the enzymatic activity of metalloproteinases (MMPs) produced by synovial cells in response to interleukin-1beta (IL-1beta) and employed the assay to explore the biological function of gap junctions. IL-1beta produced a dose-dependent increase in MMP activity that was blocked by exposure to the gap junction inhibitors 18alpha-glycyrrhetinic acid and octanol for as few as 50 min. The inhibitors produced an immediate and marked reduction in intercellular communication, as assessed by transient current analysis using the nystatin perforated-patch method. These observations suggest that communication through gap junctions early in IL-1beta signal transduction is critical to the process of cytokine-regulated secretion of MMPs by synovial cells.

A biomechanical study of femoral neck fracture fixation with the VHS Vari-Angle Hip Fixation System.

Femoral neck fracture fixation with a new device, the VHS Vari-Angle Hip Fixation System (Biomet Orthopaedics Inc, Warsaw, IN), was studied in 14 fresh-frozen cadaver femurs. A Pauwels class III fracture was simulated in these femurs. Seven femurs were fixed by placing the screw at a high (150 degrees) angle to the femoral axis; the other 7 femurs were fixed by placing the screw at a low (135 degrees) angle to the femoral axis. Mean compressive failure load was found to be significantly higher for the high-angle group than for the low-angle group. We concluded that compared with a low-angle screw placement (135 degrees), high-angle screw placement (150 degrees) results in a biomechanically stronger fixation.