Allan W. Hennigar

Behaviours caregivers use to determine pain in non-verbal, cognitively impaired individuals.

To create a checklist of behaviours that caregivers could use to determine pain in non‐verbal individuals with mental retardationa, primary caregivers were recruited by the Division of Neurology and interviewed using a semistructured interview. Caregivers of 20 individuals were asked to recall two instances of short, sharp pain and two of longer‐lasting pain and describe the individuals behaviour. Transcribed interviews were reviewed by two of the authors and sets of non‐overlapping items were developed. Average age of the 20 individuals was 14.5 years (range 6 to 29 years) and language level averaged 10 months as scored by the MacArthur Communicative Development Inventory. All had mental retardation and 18 had epilepsy and spastic quadriplegia or hemiparesis. Thirty‐one behaviours were extracted from the interviews. The specific behaviours were often different from one child to another but the classes of behaviours (Vocal, Eating/Sleeping, Social/Personality, Facial expression of pain, Activity, Body and limbs, and Physiological) were common to almost all children. Reliability of using the checklist on interviews was very good (kappa=0.77). The checklist has excellent content validity and will be useful for caregivers of cognitively‐impaired, non‐verbal individuals to report on pain behaviours. Further research is needed to additionally assess its validity and sensitivity.

Prospective relation between catastrophizing and residual pain following knee arthroplasty: two-year follow-up.

BACKGROUND Pain is the primary indication for both primary and revision total knee arthroplasty (TKA); however, most arthroplasty outcome measures do not take pain into account. OBJECTIVE To document the prospective pain experience following TKA, with subjective pain-specific questionnaires to determine if comorbidities, preoperative pain or preoperative pain catastrophizing scores are predictive of long-term pain outcomes. METHODS Fifty-five patients with a primary diagnosis of osteoarthritis of the knee, who were scheduled to undergo TKA, were asked to fill out the McGill Pain Questionnaire (MPQ) and the Pain Catastrophizing Scale (PCS) preoperatively and at three, 12 and 24 months follow-up. Comorbidities were extracted from the Queen Elizabeth II Health Sciences Centre health information system. RESULTS The overall response rate (return of completed questionnaires) was 84%. There was a significant decrease in the MPQ scores (P<0.05) postoperatively. PCS scores did not change over time. Receiver operating characteristic curves revealed the number of comorbidities per patient predicted the presence of pain postoperatively, as documented by the numerical rating subscale of the MPQ at 24 months (P<0.05). Receiver operating characteristic curves for preoperative PCS and rumination subscale scores predicted the presence of pain, as measured by the Pain Rating Index subscale of the MPQ at 24 months (P<0.05). Preoperative PCS scores and comorbidities were significantly higher in the persistent pain group (P<0.05). CONCLUSIONS The number of comorbidities predicted the presence of pain at 24 months follow-up and, for the first time, preoperative PCS scores were shown to predict chronic postoperative pain. This may enable the identification of knee arthroplasty patients at risk for persistent postoperative pain, thus allowing for efficient administration of preoperative interventions to improve arthroplasty outcomes.

Continued stabilization of trabecular metal tibial monoblock total knee arthroplasty components at 5 years—measured with radiostereometric analysis

Background and purpose The trabecular metal tibial monoblock component (TM) is a relatively new option available for total knee arthroplasty. We have previously reported a large degree of early migration of the trabecular metal component in a subset of patients. These implants all appeared to stabilize at 2 years. We now present 5-year RSA results of the TM and compare them with those of the NexGen Option Stemmed cemented tibial component (Zimmer, Warsaw IN). Patients and methods 70 patients with osteoarthritis were randomized to receive either the TM implant or the cemented component. RSA examination was done postoperatively and at 6 months, 1 year, 2 years, and 5 years. RSA outcomes were translations, rotations, and maximum total point motion (MTPM) of the components. MTPM values were used to classify implants as “at risk” or “stable”. Results At the 5-year follow-up, 45 patients were available for analysis. There were 27 in the TM group and 18 in the cemented group. MTPM values were similar in the 2 groups (p = 0.9). The TM components had significantly greater subsidence than the cemented components (p = 0.001). The proportion of “at risk” components at 5 years was 2 of 18 in the cemented group and 0 of 27 in the TM group (p = 0.2). Interpretation In the previous 2-year report, we expressed our uncertainty concerning the long-term stability of the TM implant due to the high initial migration seen in some cases. Here, we report stability of this implant up to 5 years in all cases. The implant appears to achieve solid fixation despite high levels of migration initially.

Shell and tissue growth of juvenile sea scallops (Placopecten magellanicus) in suspended and bottom culture in Lunenburg Bay, Nova Scotia

Abstract Hatchery-reared juvenile sea scallops Placopecten magellanicus (mean shell height = 22.2 ± 0.1 mm) were grown uncontained on the seabed (5–9 m depth) and suspended in pearl nets (3 m above the seabed) at three sites (Site 1, 2 and 3) in Lunenburg Bay, N. S., Canada, between March 1992 and March 1993. Shell and tissue growth rates reached their peak in mid-summer and decreased to the lowest values in winter, although growth never stopped. Monthly measurements of shell heights of individually tagged scallops in pearl nets (100 per net) and on the seabed, yielded mean (± s.e.) annual growth rates of 93 ± 5.5 and 117 ± 4.5 μm/day, respectively, at Site 1, 72 ± 3.0 and 93 ± 3.8 μm/day at Site 2, and 79 ± 2.8 and 73 ± 5.6 μm/day at Site 3. There were significant differences in shell growth rates among the three sites and between the two culture methods in most of the months. The highest shell growth rates generally occurred at Site 2, regardless of culture method. Shell growth rates were significantly higher in bottom than in suspended culture during most measurement periods. Mean final soft tissue condition index of scallops in suspended culture was significantly higher than in bottom culture at Site 2. Mean final adductor muscle condition index and mean final whole dry weights of scallops were significantly lower in suspended culture than in bottom culture at Site 2. Water temperature at all three sites ranged from ~ −2 to 16 °C during the year. There were significant differences in annual mean particulate organic matter concentration between depths, but not among sites. Annual mean chlorophyll concentration differed among sites, but not between depths within sites. Stepwise multiple regression analyses, with water temperature, total particulate matter concentration, and chlorophyll concentration as independent variables, were highly significant for all sites and culture methods. They explained between 46% and 66% of the total variance of shell growth rates in suspended culture and between 36% and 78% in bottom culture, respectively and 55% and 80% for soft tissue growth rates of scallops in suspended and bottom culture, respectively. Growth of scallops in bottom culture at these shallow sites is comparable to animals of the same seed populations grown in the more expensive and labour-intensive suspended culture at the same sites.

Perspectives of Canadian Stakeholders on Criteria for Appropriateness for Total Joint Arthroplasty in Patients With Hip and Knee Osteoarthritis.

As rates of total joint arthroplasty (TJA) for osteoarthritis (OA) rise, there is a need to ensure appropriate use. We undertook this study to develop criteria for appropriate use of TJA.

Inducible displacement of a trabecular metal tibial monoblock component.

Radiostereometric analysis is a highly accurate technique that can be used for measuring micromotion at the bone-implant interface. The purpose of this study was to compare the inducible displacement of the uncemented Trabecular Metal (TM; Zimmer, Warsaw, Ind) tibial monoblock component with that of a cemented implant. Inducible displacement of 14 uncemented TM components and 11 cemented components was measured 24 to 48 months postoperatively. Longitudinal migration of the implants was also measured with radiostereometric analysis at 6, 12, and 24 months postoperatively. The uncemented TM group had significantly lower inducible displacement than the cemented components. Significant correlations were found between longitudinal migration and the inducible displacement tests. The low values of inducible displacement in the TM group indicated good fixation and a promising long-term prognosis.

Decision making in migraine patients taking sumatriptan: an exploratory study.

Until recently, much of the medical and psychological literature has examined and conceptualized the taking of medication from the viewpoint of adherence to or compliance with recommendations from health professionals. However, some authors have argued that medication taking is mostly determined by patient decision making. In order to investigate the factors and processes influencing the patients decision to take or not take abortive therapy for migraines, 20 migraineurs (according to International Headache Society criteria) were asked, using a semistandardized interview, what factors influenced their decision to take or not take sumatriptan when they had a migraine. Qualitative analysis revealed a 2‐stage decision‐making process. First, the patient collects information from interoceptive and environmental cues (symptom monitoring) to predict whether the headache that is beginning will become a migraine. Then, if the patient decides it is a migraine, he or she weighs various factors to decide whether to take sumatriptan. These results are consistent with the current cognitive psychology literature on decision‐making processes and could lead to significant improvements in understanding the process by which patients make decisions about taking sumatriptan and, ultimately, could lead to better patient education and more effective headache control. They also open a whole new field in the empirical investigation of medication‐taking behavior.

Longitudinal migration and inducible displacement of the Mobility Total Ankle System Radiostereometry in 23 patients with 2 years of follow-up

Background and purpose RSA can be used for early detection of unstable implants. We assessed the micromotion of the Mobility Total Ankle System over 2 years, to evaluate the stability of the bone-implant interface using radiostereometric analysis measurements of longitudinal migration and inducible displacement. Patients and methods 23 patients were implanted with the Mobility system. Median age was 62 (28–75) years and median BMI was 28.8 (26.0–34.5). Supine radiostereometric analysis examinations were done from postoperatively to the 2-year follow-up. Standing examinations were taken from the 3-month to the 2-year follow-up. Migrations and displacements were assessed using model-based RSA software (v. 3.2). Results The median maximum total point motion (MTPM) for the implants at 2 years was 1.19 (0.39–1.95) mm for the talar component and 0.90 (0.17–2.28) mm for the spherical tip of the tibial component. The general pattern for all patients was that the slope of the migration curves decreased over time. The main direction of motion for both components was that of subsidence. The median 2-year MTPM inducible displacement for the talar component was 0.49 (0.27–1.15) mm, and it was 0.07 (0.03–0.68) mm for the tibial component tip. Interpretation The implants subside into the bone over time and under load. This corresponds to the direction of primary loading during standing or walking. This statistically significant motion may become a clinically significant finding that would correspond with premature implant failure.

Validation and Precision of Model-Based Radiostereometric Analysis (MBRSA) for Total Ankle Arthroplasty:

Background: The goal of this study was to design a RSA marker insertion protocol to evaluate the stability of the bone-implant interface of a TAA prosthesis, and to validate that this marker insertion protocol can be combined with MBRSA technology to provide clinically adequate precision in assessing the micromotion of the TAA prosthesis. Methods: The Mobility™ Total Ankle System was used in this study. A marker placement protocol was developed with a Phantom Protocol. The Improved Marker Placement Protocol was used in 20 patients. Postoperative RSA double exams were taken. Condition Numbers (CN) were used to assess the marker distribution. The system precision was defined as the standard deviation of the double exams (MTE, MRE). MBRSA software was used to evaluate the double exams. Results: The RSA marker insertion technique for the 20 in vivo cases provided satisfactory results. CNs in all subjects but one were below 50 mm−1 and implied a desirable marker configuration. The tibial sphere MTE was 0.07 mm and the talar was 0.09 mm. The talar MRE was 0.51 degrees. Conclusion: The system precision for these in vivo TAA implants was within the normal range identified by RSA studies, and comparable to the existing TAA RSA studies. This study demonstrated a reliable RSA marker insertion technique in both the tibia and talus. The study confirms that the insertion and MBRSA technique allows the typical high precision demonstrated in other RSA studies

Implementation and validation of an implant-based coordinate system for RSA migration calculation

An in vitro radiostereometric analysis (RSA) phantom study of a total knee replacement was carried out to evaluate the effect of implementing two new modifications to the conventional RSA procedure: (i) adding a landmark of the tibial component as an implant marker and (ii) defining an implant-based coordinate system constructed from implant landmarks for the calculation of migration results. The motivation for these two modifications were (i) to improve the representation of the implant by the markers by including the stem tip marker which increases the marker distribution (ii) to recover clinical RSA study cases with insufficient numbers of markers visible in the implant polyethylene and (iii) to eliminate errors in migration calculations due to misalignment of the anatomical axes with the RSA global coordinate system. The translational and rotational phantom studies showed no loss of accuracy with the two new measurement methods. The RSA system employing these methods has a precision of better than 0.05 mm for translations and 0.03 degrees for rotations, and an accuracy of 0.05 mm for translations and 0.15 degrees for rotations. These results indicate that the new methods to improve the interpretability, relevance, and standardization of the results do not compromise precision and accuracy, and are suitable for application to clinical data.