The Impact of Three-Dimensional Humeral Planning and Standard Transfer Instrumentation on Reconstruction of Native Humeral Anatomy for Anatomic Total Shoulder Arthroplasty.

BACKGROUND: Preoperative three-dimensional CT-based planning for anatomic total shoulder arthroplasty (TSA) has grown in popularity in the past decade with the primary focus on the glenoid. Little research has evaluated if humeral planning has any effect on the surgical execution of the humeral cut or the positioning of the prosthesis. METHODS: Three surgeons performed a prospective study utilizing 3D-printed humeri printed from CTs of existing patients, which were chosen to be -3, -1, 0, 1 and 3 standard deviations of all patients in a large database. A novel 3D printing process was utilized to 3D print not only the humerus, but also all four rotator cuff tendons. For each surgical procedure, the printed humerus was mounted inside a silicon shoulder, with printed musculature and skin, and with tensions similar to human tissue requiring standard retraction and instruments to expose the humerus. Three phases of the study were designed: Phase 1: Humeral neck cuts were performed on all specimens without any preoperative humeral planning, Phase 2: 3D planning was performed, and the cuts and implant selection were repeated, Phase 3: A neck shaft angle guide and digital calipers were used to measure humeral osteotomy thickness to aid in the desired humeral cut. All humeri were digitized. The difference between the prosthetic center of rotation (COR) and ideal COR was calculated. The percentage of patients with a varus neck shaft angle (NSA) was calculated for each phase. The difference in planned and actual cut thickness was also compared. RESULTS: For both 3D change in COR and medial to lateral change in COR, use of preoperative planning alone and with standard transfer instrumentation resulted in a significantly more anatomic restoration of ideal COR. The deviations from planned cut thickness decreased with each phase: Phase 1: 2.6±1.9 mm, Phase 2: 2.0±1.3 mm, Phase 3: 1.4±0.9 mm (p = 0.041 for Phase 3 vs Phase 1). For NSA, in Phase 1: 7/15 (47%) cases were in varus, in Phase 2: 5/15 (33%) were in varus and Phase 3: 1/15 (7%) were in varus (p =0.013 for Phase 3 vs Phase 1). CONCLUSIONS: Use of preoperative 3-D humeral planning for stemless anatomic TSA improved prosthetic humeral center of rotation, whether performed with or without standard transfer instrumentation. The use of a neck-shaft angle cut guide and calipers to measure cut thickness significantly reduced the percentage of varus humeral cuts and deviation from planned cut thickness.

Influence of backside seating parameters and augmented baseplate components in virtual planning for reverse shoulder arthroplasty.

BACKGROUND: The primary goal of this investigation was to examine the influence of a backside seating percentage variable on volume of reamed bone and contact area in virtual planning for glenoid baseplate placement for reverse total shoulder arthroplasty (RTSA). The secondary goal was to assess how the option of augmented glenoid baseplate components affected reamed volume and cortical contact area of virtually positioned baseplates. METHODS: Nine surgeons virtually planned 30 RTSA cases using a commercially available software system. The 30 cases were chosen to span a spectrum of glenoid deformity. The study consisted of 3 phases. In phase 1, cases were planned with the backside seating percentage blinded and without the option of augmented baseplate components. In phase 2, the backside seating parameter was unblinded. In phase 3, augmented baseplate components were added as an option. Implant version and inclination were recorded. By use of computer-assisted design models, total volume of bone reamed, as well as reamed cortical volume and cancellous volume, was calculated. Total, cortical, and cancellous baseplate contact areas were also calculated. Finally, total glenoid lateralization was calculated for each phase and compared. RESULTS: Mean implant version was clinically similar across phases but was statistically significantly lower in phase 3 (P = .006 compared with phase 1 and P = .001 compared with phase 2). Mean implant inclination was clinically similar across phases but was statistically significantly lower in phase 3 (P < .001). Phase 3 had statistically significantly lower cancellous and total reamed bone volumes compared with phase 1 and phase 2 (P < .001 for all comparisons). Phase 3 had statistically significantly larger cortical contact area, lower cancellous contact area, and larger total contact area compared with phase 1 and phase 2 (P < .001 for all comparisons). Phase 3 had significantly greater glenoid lateralization (mean, 10.5 mm) compared with phase 1 (mean, 7.8 mm; P < .001) and phase 2 (mean, 7.9 mm; P < .001). CONCLUSIONS: Across a wide range of glenoid pathology during virtual surgical planning, experienced shoulder arthroplasty surgeons chose augmented baseplates frequently, and the option of a full-wedge augmented baseplate resulted in statistically significantly greater correction of glenoid deformity, improved total and cortical baseplate contact area, less cancellous reamed bone, and greater glenoid lateralization. Backside seating information does not have a significant impact on how glenoid baseplates are virtually positioned for RTSA, nor does it impact the baseplate contact area or volume of reamed bone.

The addition of preoperative three-dimensional analysis alters implant choice in shoulder arthroplasty.

Background: The primary objective of the present study was to investigate how preoperative imaging modalities including 3D computed tomography (CT) scans with preoperative planning software affect implant choice for shoulder arthroplasty. Methods: X-ray, uncorrected 2D CT scans, and 3D CT scans from 21 patients undergoing primary arthroplasty were reviewed by five shoulder surgeons. Each surgeon measured glenoid version, inclination and humeral head subluxation, and then selected an anatomic or reverse shoulder arthroplasty implant based only on these imaging parameters. Each surgeon virtually positioned the implant. Agreement between surgeons and changes in plan for individual surgeons between imaging modalities were assessed. Results: Average measurements of native version, inclination, and subluxation were similar across all imaging modalities with very good interobserver reliability. Overall, there was a high rate of variability in choice of implant depending on imaging modality. Agreement on implant selection between surgeons improved from 68.6% using x-ray to 80.0% with 3D CT. Introducing age added significant variability, reducing agreement on implant choice to 61.0% with 3D CT. Conclusions: The use of preoperative 3D planning changes implant choice in nearly one-third of cases compared to plain radiographs and improves surgeon agreement on implant choice compared to x-ray and 2D CT.Level of evidence: III.

Outcomes of manual small-incision cataract surgery using standard 22 dioptre intraocular lenses at Nkhoma Eye Hospital, Malawi.

The aim of this study was to investigate the outcomes of sutureless, manual small-incision cataract surgery (SICS) in rural sub-Saharan Africa using standard intraocular lenses (IOLs). In order to assess the quality of surgery, we prospectively evaluated the visual outcomes of 1455 consecutive cataract operations performed in 2006 in patients ≥40 years at Nkhoma Eye Hospital, Malawi. All operations used standard 22-dioptre IOLs without pre-operative biometry. Outcomes were categorised according to the World Health Organization criteria, and causes of a poor outcome were recorded. Mean age of patients was 71.5 ± 9.5 years, and 53 % were female. Pre-operatively, 64 % of eyes had a visual acuity (VA) <6/60, and 41.3 % of eyes were blind (VA < 3/60). Without correction (uncorrected VA), nearly eighty percent (78.7 %) achieved a 'good' outcome (VA 6/6-6/18), 19.8 % were 'borderline' (VA < 6/18-6/60), and 1.5 % had a poor (VA < 6/60) outcome. With pinhole-correction, the proportion of good outcomes increased to 89.4 %, and poor outcomes decreased to 0.9 %. Poor outcomes were most commonly due to ocular co-morbidities (54.5 %) and refractive error (36.4 %). Older age and pre-operative blindness were strongly associated with borderline or poor visual outcomes. The most common surgical complication was posterior capsule tear (without vitreous loss). In a rural African environment, using standard IOL power plus SICS can lead to a high proportion of good outcomes and a low frequency of surgical complications. A comparative study is required to determine if any additional benefit in visual outcomes can be gained by the addition of biometry.

Follow-up survey of cataract surgical coverage and barriers to cataract surgery at Nkhoma, Malawi.

PURPOSE: Nkhoma Eye Hospital, Malawi provides high volume, high quality free cataract surgery to people in its catchment region of Central-Malawi. However, a previous survey in 2000 indicated that only 1 in 7 people with bilateral blindness from cataract had received surgery in a 10-mile radius of Nkhoma. METHODS: We conducted a population-based survey in 2006 in the 32 villages within a 10-mile radius of Nkhoma Hospital in people aged ≥ 40 years in order to investigate the cataract surgical coverage (CSC) and barriers to cataract surgery. RESULTS: The prevalence of blindness (visual acuity [VA] <3/60 in better eye) in 835 people aged ≥ 40 was 1.3% (95% CI 0.5-2.1), of which 36.4% was due to cataract. Overall, the CSC was 83.3%, and for eyes (VA<3/60) was 66.0%. The CSC was lower in females compared to males (73.3% vs. 100.0%. P < 0.001). The most common barrier to surgery was cost (58%). CONCLUSION: Our results demonstrate a 5-fold increase in coverage in the 6 years, primarily by increasing efficiency of the service provider and providing a community screening and referral service. Supporting the ophthalmic personnel with appropriate infrastructure and management has been central to this shift. Implementing an active case finding and referral mechanism has enabled this unit to provide regular high volume cataract surgery. There is a need to understand the factors influencing perceptions about cost as a barrier in this community and the disparity between need and access to services for women.

Cataract surgical coverage and outcome of cataract surgery in a rural district in Malawi.

BACKGROUND: Cataract is the leading cause of blindness in Malawi. We sought to determine the cataract surgical coverage and the outcome of cataract surgery in a rural district in Malawi to assess past performance of cataract surgical services. METHODS: From July to October 1999 we conducted a multistage random cluster survey to include 1630 residents aged 50 years or more in Chikwawa District. Visual acuity, cause of vision loss, history of cataract surgery and cause of poor vision (if less than 6/60) were assessed. Cataract surgical coverage, sight restoration rate and outcome were calculated by person and eye and for men and women separately. RESULTS: We examined 1384 people (84.9% of target). Twenty-one people (12 men and 9 women) (30 eyes) had received cataract surgery. The cataract surgical coverage rate was 35.6% (44.4% for men and 28.1% for women [odds ratio 2.0, 95% confidence interval 0.6-7.0]) at a visual acuity level of 6/60, and 55.3% (60.0% for men and 50.0% for women [odds ratio 1.5, 95% confidence interval 0.3-6.7]) at a level of 3/60. Only one eye of one subject had received an intraocular lens. Presenting visual acuity was 6/18 or better in 7 eyes (23.3%), 6/24 to 6/60 in 7 eyes, and worse than 6/60 in 16 eyes (53.3%). Among the 16 eyes with visual acuity less than 6/60, the vision could be improved in 8 with provision of aphakic spectacles. INTERPRETATION: Cataract surgical coverage in this population is similar to that reported from other countries in Africa. As in other settings, cataract surgical coverage was lower in women than in men. Poor outcomes in this population are partly due to surgical complications and partly due to a lack of aphakic correction. Surgical promotion programs will need to focus on differentiating intraocular lens surgery from (previously practised) intracapsular cataract extraction surgery.