A two-year comparison of reverse total shoulder arthroplasty mini-humeral tray and augmented mini-glenoid baseplate implants vs. standard implants

BACKGROUND

Patients who undergo reverse total shoulder arthroplasty (RTSA) are getting younger with greater function expectations. This retrospective, longitudinal study of prospectively collected data compared perceived shoulder function and strength, active shoulder mobility, radiographic evidence of scapular notching, and implant survival over the initial 2-years post-RTSA among patient groups who received either standard central fixation point liner and glenoid baseplate implants, or lower size profile mini-humeral tray with offset trunnion options and mini-augmented glenoid baseplate implants.

MATERIALS AND METHODS

Patients who underwent primary RTSA using standard central fixation point liner and glenoid baseplate implants (Group 1, n = 180) were compared with patients who underwent primary RTSA using lower size profile mini-humeral tray with offset trunnion options and mini-augmented glenoid baseplate implants (Group 2, n = 53) for active shoulder mobility, American Shoulder and Elbow Surgeons (ASES) score, perceived ability to lift 10 lbs (4.5 kg) overhead, radiographic evidence of scapular notching, and implant survival. Data was collected pre-surgery, 6-weeks, 6-months, 1-year, and 2-years post-RTSA (p ≤ 0.05).

RESULTS

More Group 2 patients had more complex B or C Walch glenoid morphology, while Group 1 had more A1 or A2 types (p ≤ 0.001). Group 2 had greater active shoulder flexion at 6-months, 1-year, and 2-years (p ≤ 0.018) and external rotation (in adduction) at 6-months and 2-years (p ≤ 0.004) compared to Group 1, with higher ASES scores at 6-months and 2-years (p ≤ 0.026) (with small-to-medium effect sizes), and with more patients meeting or exceeding the minimal clinically important difference (MCID) at 2-years (p = 0.045) and patient acceptable symptomatic state (PASS) levels at 6-months, 1-year and 2-years (p ≤ 0.045). Scapular notching was identified in six of 53 (11.3%) Group 2 patients and in 32 of 180 (17.7%) Group 1 patients. Group 1 patients had more grade 2 or greater scapular notching grades compared to Group 2 (p = 0.04). Implant survival was comparable with Group 1 = eight of 180 (4.4%) and Group 2 = 1 of 53 (1.9%) of patients requiring removal for 95.6% and 98.1% implant survival, respectively.

CONCLUSION

Limited scapular notching and excellent implant survival was observed in both groups. Despite including individuals with more complex glenoid deficiency, patients receiving the lower size profile implants generally displayed better active shoulder mobility and perceived shoulder function compared to those who received standard implants. These patients also more frequently met or exceeded the MCID by 2-years post-RTSA and PASS levels by 6-months, 1-year, and 2-years post-RTSA, with lower scapular notching grades.

LEVEL OF EVIDENCE

Retrospective comparative study.

Mini-augmented glenoid baseplate and mini-humeral tray reverse total shoulder arthroplasty implant comparisons: two-year clinical outcomes

BACKGROUND

Augmented glenoid baseplate and offset humeral tray reverse total shoulder arthroplasty (RTSA) implants may decrease the mechanical impingement that creates scapular notching and improve shoulder function. This study evaluated the clinical efficacy of three different RTSA glenoid baseplate and offset humeral tray combinations for patient-reported shoulder function, pain and instability, radiographic imaging evidence of glenoid baseplate or humeral stem subsidence and migration, bony changes associated with implant loosening, and scapular notching over the initial 2 years post-RTSA. Primary outcomes included active shoulder mobility, perceived function, pain, instability, scapular notching, and implant survival.

METHODS

Sixty-seven patients from 6 research sites received one of three different glenoid baseplate and humeral tray combinations. Group 1 (n = 21) received a mini-augmented glenoid baseplate with a standard humeral tray; Group 2 (n = 23) received a standard glenoid baseplate and a mini-humeral tray with 3 trunnion offset options; Group 3 (n = 23) received both a mini-augmented glenoid baseplate and a mini-humeral tray with 3 trunnion offset options. Subjects underwent radiologic evaluation, completed the ASES scale, the EQ-5D-5L quality of life scale, VAS shoulder pain and instability questions, and active shoulder mobility measurements pre-operatively, and 6-weeks, 6-months, 1-2 years post-RTSA.

RESULTS

Improved active shoulder mobility, quality of life, perceived function, decreased shoulder pain and instability, excellent implant survival and minimal scapular notching were observed for all groups. Group 3 had better overall active shoulder mobility than the other groups and better perceived function than Group 1.

CONCLUSION

The group that received the mini-augmented glenoid baseplate and mini-humeral tray combination had better overall active shoulder flexion, external rotation at 90° abduction, and internal rotation. This group also had better perceived shoulder function compared to the group that received a mini-augmented glenoid baseplate with a standard humeral tray.

Liposomal bupivacaine nerve block provides better pain control post-total shoulder arthroplasty than continuous indwelling catheter

BACKGROUND

Pain control is essential to successful total shoulder arthroplasty (TSA).

MATERIALS AND METHODS

This non-blinded, randomized clinical trial compared shoulder pain, narcotic use, interscalene (IS) block application time, and costs in 76 subjects who were randomly assigned to receive either a single injection IS nerve block of 10 cc (133 mg) liposomal bupivacaine mixed with 10 cc of 0.5% bupivacaine (Group 1), or 20 cc of 0.5% ropivacaine direct injection combined with an indwelling IS nerve block catheter delivering 0.2% ropivacaine at a continual 4 cc/h infusion for the initial 3 post-operative days (Group 2). Surgical time, local anesthesia duration, hospital stay length, morphine milligram equivalents (MME) consumed, worst shoulder pain at 24, 48 and 72 h, and complications were recorded. Patient reported function, pain and activity level surveys were completed before, and 6-week post-TSA (P < 0.05).

RESULTS

Group 1 had less pain 24-h (0.72 ± 0.8 vs. 3.4 ± 2.9, p < 0.0001) and 48-h (2.5 ± 2.2 vs. 4.8 ± 2.6, p = 0.005) post-TSA. At 24-h post-TSA, MME consumption was similar (Group 1 = 4.5 ± 6.4 vs. Group 2 = 3.7 ± 3.8, p = 0.54), but was lower for Group 1 at 48 h (0.0 ± 0.0 vs. 0.64 ± 0.99, p = 0.001). Group 2 had longer IS block application time (10.00 ± 4.6 min vs. 4.84 ± 2.7 min, p < 0.0001). Only group 2 had a strong relationship between MME consumption over the first 24-h post-TSA and pain 24-h post-TSA (r = 0.76, p < 0.0001), a moderate relationship with pain 48-h post-TSA (r = 0.59, P = 0.001), and a weak relationship with pain 72-h post-TSA (r = 0.44, P = 0.02). Significant relationships for these variables were not observed for Group 1 (r ≤ 0.30, p ≥ 0.23). Group 1 IS block costs were less/patient than Group 2 ($190.17 vs. $357.12 USD).

CONCLUSION

A single shot, liposomal bupivacaine interscalene nerve block provided better post-TSA pain control with less narcotic consumption, less time for administration and less healthcare system cost compared to interscalene nerve block using a continuous indwelling catheter.

LEVEL OF EVIDENCE

Level I, Prospective, Randomized.

Interpositional scaffold anchor rotator cuff footprint tear repair: excellent survival, healing, and early outcomes

PURPOSE

Shoulder function limitation duration after a full-thickness rotator cuff tendon (RCT) tear may influence post-repair healing and outcomes. A suture anchor was developed to improve footprint repair fixation and healing through biological fluid delivery and scaffold augmentation. The primary multicenter study objective was to evaluate RCT repair failure rate based on 6-month MRI examination, and device survival at 1-year follow-up. The secondary objective was to compare the clinical outcomes of subjects with shorter- and longer-term shoulder function limitation duration.

METHODS

Seventy-one subjects (46 men) with moderate-to-large RCT tears (1.5-4 cm), at a median 61 years of age (range = 40-76), participated in this study. Pre-repair RCT tear location/size and 6-month healing status were confirmed by an independent radiologist. Subjects with shorter- (Group 1: 17.8 ± 21 days, n = 37) and longer-term (Group 2: 185.4 ± 89 days, n = 34) shoulder function limitation durations were also compared over 1 year for active mobility, strength, American Shoulder and Elbow Surgeon's Shoulder Score (ASES score), Veterans RAND 12 Item Health Survey (VR-12), and visual analog scale (VAS) pain and instability scores.

RESULTS

Three of the 52 subjects [5.8%] who underwent 6-month MRI experienced a re-tear at the original RCT footprint repair site. By the 1-year follow-up, overall anchor survival was 97%. Although Group 2 displayed lower ASES and VR-12 scores pre-repair (ASES = 40.1 ± 17 vs. 47.9 ± 17; VR-12 physical health (PH) = 37.2 ± 9 vs. 41.4 ± 8) (p ≤ 0.048), at 3-month post-RCT repair (ASES = 61.3 ± 19 vs. 71.3 ± 20; VR-12 PH = 40.8 ± 8 vs. 46.8 ± 9) (p ≤ 0.038), and at 6-month post-RCT repair (ASES = 77.4 ± 18 vs. 87.8 ± 13; VR-12 PH = 48.9 ± 11 vs. 54.0 ± 9) (p ≤ 0.045), by 1-year post-RCT repair, groups did not differ (n.s.). Between-groups VR-12 mental health score differences were not evident at any time period (n.s.). Shoulder pain and instability VAS scores also did not differ (n.s.), displaying comparable improvement between groups from pre-RCT repair to 1-year post-RCT repair. Groups had comparable active shoulder mobility and strength recovery at each follow-up (n.s.).

CONCLUSION

At 6-month post-RCT repair, only 3/52 of patients [5.8%] had a footprint re-tear, and at 1-year follow-up, overall anchor survival was 97%. Use of this scaffold anchor was associated with excellent early clinical outcomes regardless of shoulder function impairment duration.

LEVEL OF EVIDENCE

II.

Stress shielding following stemless anatomic total shoulder arthroplasty

Background

Finite element analysis has suggested that stemless implants may theoretically decrease stress shielding. The purpose of this study was to assess the radiographic proximal humeral bone adaptations seen following stemless anatomic total shoulder arthroplasty.

Methods

A retrospective review of 152 prospectively followed stemless total shoulder arthroplasty utilizing a single implant design was performed. Anteroposterior and lateral radiographs were reviewed at standard time points. Stress shielding was graded as mild, moderate, and severe. The effect of stress shielding on clinical and functional outcomes was assessed. Also, the influence of subscapularis management on the occurrence of stress shielding was determined.

Results

At 2 years postoperatively, stress shielding was noted in 61 (41%) shoulders. A total of 11 (7%) shoulders demonstrated severe stress shielding with 6 occurring along the medial calcar. There was one instance of greater tuberosity resorption. At the final follow-up, no humeral implants were radiographically loose or migrated. There was no statistically significant difference in clinical and functional outcomes between shoulders with and without stress shielding. Patients undergoing a lesser tuberosity osteotomy had lower rates of stress shielding, which was statistically significant (p = 0.021).

Discussion

Stress shielding does occur at higher rates than anticipated following stemless total shoulder arthroplasty, but was not associated with implant migration or failure at 2 years follow-up.

Level of evidence

IV, Case series.

ACL microtrauma: healing through nutrition, modified sports training, and increased recovery time

PURPOSE

Sports injuries among youth and adolescent athletes are a growing concern, particularly at the knee. Based on our current understanding of microtrauma and anterior cruciate ligament (ACL) healing characteristics, this clinical commentary describes a comprehensive plan to better manage ACL microtrauma and mitigate the likelihood of progression to a non-contact macrotraumatic ACL rupture.

METHODS

Medical literature related to non-contact ACL injuries among youth and adolescent athletes, collagen and ACL extracellular matrix metabolism, ACL microtrauma and sudden failure, and concerns related to current sports training were reviewed and synthesized into a comprehensive intervention plan.

RESULTS

With consideration for biopsychosocial model health factors, proper nutrition and modified sports training with increased recovery time, a comprehensive primary ACL injury prevention plan is described for the purpose of better managing ACL microtrauma, thereby reducing the incidence of non-contact macrotraumatic ACL rupture among youth and adolescent athletes.

CONCLUSION

Preventing non-contact ACL injuries may require greater consideration for reducing accumulated ACL microtrauma. Proper nutrition including glycine-rich collagen peptides, or gelatin-vitamin C supplementation in combination with healthy sleep, and adjusted sports training periodization with increased recovery time may improve ACL extracellular matrix collagen deposition homeostasis, decreasing sudden non-contact ACL rupture incidence likelihood in youth and adolescent athletes. Successful implementation will require compliance from athletes, parents, coaches, the sports medicine healthcare team, and event organizers. Studies are needed to confirm the efficacy of these concepts.

LEVEL OF EVIDENCE

V.

History of Ulnar Collateral Ligament Injury and College Pitcher Fastball Profiles: A Retrospective, Observational, Live Pitching Analysis

PURPOSE

The aim of this study was to retrospectively compare the fastball profiles of pitchers who had previously sustained grade I or II ulnar collateral ligament (UCL) injuries, were rehabilitated, and released back for competition with those of pitchers with no history of elbow injury.

METHODS

Eighteen pitchers from the pitching staff of 1 National Collegiate Athletic Association Division III team participated in this study. Group 1 had a history of grade I or II UCL injury (n = 8), and group 2 (n = 10) did not. A computerized pitch tracking device was used to analyze ball movement and pitching mechanics. The hypothesis was that the pitchers with a history of injury (group 1) would display differing fastball velocity-ball movement relationships compared to those without (group 2).

RESULTS

The groups had similar heights, weights, pitching experiences, and arm slot positions at ball release. The pitching coach-determined preinjury arm slot position and the postinjury computerized pitch tracking device measurements after return to competition displayed strong agreement (r = 0.83), suggesting comparable pre and postinjury pitching techniques. The groups had comparable glenohumeral joint range of motion and fastball profiles, except that group 1 released the ball at a 2.5 times lesser horizontal distance away from the pitching rubber center. Group 2 also displayed consistently more robust and more frequent fastball movement relationships with velocity, horizontal break, and vertical break than group 1.

CONCLUSIONS

Reduced horizontal ball release distances at comparable vertical ball release heights without changes in the arm slot position suggest that pitchers with a history of grade I or II UCL injury have greater contralateral trunk tilt and elbow flexion at ball release. Increased contralateral trunk tilt may occur to increase pitch velocity at the expense of ball movement while placing the pitching elbow in a potentially injurious position. Computerized fastball profile analysis using a computerized pitch tracking device, in conjunction with coach pitching technique observation, and team medical staff clinical examination may help better identify pitchers with an increased risk of UCL injury.

TYPE OF STUDY/LEVEL OF EVIDENCE

Diagnostic II.

Editorial Commentary: Time-Zero Biomechanical Shoulder Instability Studies Are Valuable But Limited Because They Do Not Replicate Clinical Dynamics

Severe anterior shoulder instability with glenoid bone loss can be very difficult to treat. A recent cadaveric, biomechanical, time-zero study compared the stability of Bankart repair with long head of the biceps brachi transfer versus conjoined tendon transfer in the scenario of 20% anteroinferior glenoid bone loss. The result is long head of the biceps tendon transfer in combination with the Bankart repair provided the best overall condition compared to Bankart repair alone, or with a conjoined tendon transfer. However, a limitation is that this does not confirm that this surgical approach would provide sufficient long-term noncontractile shoulder stability to withstand repetitive soft-tissue loading in a dynamic, clinical situation.

Trunk and lower extremity long-axis rotation exercise improves forward single leg jump landing neuromuscular control

BACKGROUND

Anterior cruciate ligament (ACL) injuries often involve sudden single leg loading with directional changes. Trunk and lower extremity (LE) load transfer and muscle power are directly coupled during these movements. The effect of trunk and LE long-axis rotation training on forward single leg drop jump landing and stabilization (FSLDJLS) was studied.

METHODS

Using block randomization (gender), 36 (18 men, 18 women) subjects were assigned to experimental (nine, 20 min exercise sessions) and control groups with equal subject number. Ground reaction force (1000 Hz), kinematic (60 Hz) and LE EMG (1000 Hz) data were synchronously collected. Statistical analysis compared pre- and post-test neuromuscular control mean change differences (MCD), and hip flexion-LE peak EMG % maximum volitional isometric contraction (%MVIC) (expressed as decimal equivalents), mean change difference (MCD) relationships.

RESULTS

The experimental group had greater landing knee flexion (3.5 ± 3.6° vs. -0.4 ± 3.3°, p = .002) MCD, greater dynamic LE stiffness after landing (0.09 ± 0.14 vs. -0.11 ± 0.14, p = .001) MCD, and increased gluteus maximus (GMAX) (0.20 ± 0.39%MVIC vs. -0.23 ± 0.46%MVIC, p = .006) and gluteus medius (GMED) EMG amplitude (0.22 ± 0.31 vs. -0.07 ± 0.36%MVIC, p = .018) MCD. This group also had decreased GMAX (-166.5 ± 403.6 ms vs. 89.3 ± 196 ms, p = .025), GMED (-75.9 ± 126.8 ms vs. 131.2 ± 207.1 ms, p = .002) and vastus lateralis (-109.1 ± 365 ms vs. 205.5 vs. 510 ms, p = .04) activation duration MCD. More experimental group subjects had increased landing knee flexion MCD (15/18 vs. 8/18, p = .015), increased dynamic LE stiffness MCD (15/18 vs. 2/18, p < .0001) and increased GMAX (15/18 vs. 7/18, p = .006) and GMED (17/18 vs. 10/18, p = .007) EMG amplitude MCD, and reduced GMAX (12/18 vs. 6/18, p = .046), GMED (11/18 vs. 5/18, p = .044), rectus femoris (12/18 vs. 6/18, p = .046), and vastus lateralis (13/18 vs. 7/18, p = .044) EMG activation duration MCD. Only the experimental group displayed significant relationships between landing and peak hip flexion and peak LE EMG amplitude MCD.

CONCLUSION

Increased dynamic LE stiffness, increased hip muscle EMG amplitude and decreased hip and knee muscle activation duration MCD in the experimental group suggests improved LE neuromuscular control.

Sex-related differences in stemless total shoulder arthroplasty

Background

Methods

Results

Conclusion

Distal biceps brachii tendon repair: a systematic review of patient outcome determination using modified Coleman methodology score criteria

PURPOSE

This systematic literature review evaluated the methodological research design quality of studies that evaluated patient outcomes following distal biceps brachii tendon repair and developed evidence-based recommendations for future patient clinical outcomes research.

METHODS

Following the preferred reporting items for systematic reviews and meta-analyses criteria, and using "biceps brachii", "tendon", "repair" and "outcome assessment" search terms, the CINAHL, Academic Search Premier and MEDLINE databases were searched from January 1960-October 2015. The modified Coleman methodology score (MCMS) served as the primary outcome measure. Descriptive statistical analysis was performed for composite and component MCMS and for patient outcome assessment methodology use frequency.

RESULTS

A total of 93 studies were evaluated. Overall MCMS was low (57.1 ± 14). Only 12 (12.9 %) had prospective cohort or randomized controlled trial designs. There was a moderate relationship between publication year and MCMS (r = 0.53, P < 0.0001). Although 61 studies (65.6 %) had adequate surgical descriptions, only 3 (3.2 %) had well-described rehabilitation. Of 2253 subjects, only 39 (1.7 %) were women. Studies published after 2008 had higher MCMS scores than studies published earlier (61.3 ± 10 versus 52.9 ± 16, P = 0.003).

CONCLUSION

Although overall research study methodological scores improved on average since 2008, generally low MCMS scores, retrospective designs, lack of eccentric elbow flexor or supinator strength testing, and poorly described surgical and rehabilitation descriptions remain commonplace. These findings decrease clinical study validity and generalizability.

LEVEL OF EVIDENCE

III.

Reverse-total shoulder arthroplasty cost-effectiveness: A quality-adjusted life years comparison with total hip arthroplasty

AIM: To compare reverse-total shoulder arthroplasty (RSA) cost-effectiveness with total hip arthroplasty cost-effectiveness.

METHODS: This study used a stochastic model and decision-making algorithm to compare the cost-effectiveness of RSA and total hip arthroplasty. Fifteen patients underwent pre-operative, and 3, 6, and 12 mo post-operative clinical examinations and Short Form-36 Health Survey completion. Short form-36 Health Survey subscale scores were converted to EuroQual Group Five Dimension Health Outcome scores and compared with historical data from age-matched patients who had undergone total hip arthroplasty. Quality-adjusted life year (QALY) improvements based on life expectancies were calculated.

RESULTS: The cost/QALY was $3900 for total hip arthroplasty and $11100 for RSA. After adjusting the model to only include shoulder-specific physical function subscale items, the RSA QALY improved to 2.8 years, and its cost/QALY decreased to $8100.

CONCLUSION: Based on industry accepted standards, cost/QALY estimates supported both RSA and total hip arthroplasty cost-effectiveness. Although total hip arthroplasty remains the quality of life improvement “gold standard” among arthroplasty procedures, cost/QALY estimates identified in this study support the growing use of RSA to improve patient quality of life.

In situ comparison of varying composite tibial tunnel interference screws used for ACL soft tissue graft fixation

PURPOSE

This mechanical study using an in vitro porcine model compared composite interference screw fixation of soft tissue ACL grafts in tibial tunnels.

METHODS

Forty-eight porcine profundus tendons and tibiae were divided into four groups of 12 closely matched specimens. Equivalent diameter grafts were assigned to each group. Tibial bone tunnels were drilled to 0.5mm greater than graft diameter. Grafts were fixed in tunnels using one 10 × 35 mm composite interference screw designed by four different manufacturers. Maximal insertion torque and perceived within group mechanical testing outcome predictions were recorded. Constructs were potted and loaded into a six degrees of freedom clamp that placed the servohydraulic device tensile loading vector in direct tunnel alignment. Constructs were pre-loaded to 25 N, pre-conditioned between 0 and 50 N for 10 cycles (0.5 Hz), submaximally tested between 50 and 250 N for 500 cycles (one hertz) and load to failure tested at 20mm/min.

RESULTS

Statistically significant differences were not observed between groups for displacement during submaximal cyclic loading, yield load, displacement at yield load, stiffness, ultimate load at failure and displacement at ultimate load. One composite screw group displayed a slightly greater proportion of specimens that required use of more than one screw during insertion.

CONCLUSIONS

Under highly controlled conditions groups displayed comparable fixation.

Progressive resistance, whole body long-axis rotational training improves kicking motion motor performance

OBJECTIVES

To evaluate lower extremity muscle activation, peak resultant ground reaction force (GRF) production and quickness during performance of a kicking motion following progressive resistance, whole body long-axis rotational training.

DESIGN

Randomized, controlled study.

SETTING

Kinesiological research laboratory.

PARTICIPANTS

Thirty-six healthy subjects were assigned to a training (Group 1) or to a control (Group 2) group.

MAIN OUTCOME MEASURES

Time-synchronized EMG (1000 Hz), peak resultant GRF (1000 Hz) and two-dimensional kinematic (60 Hz) data were collected as subjects responded to an audio cue by kicking a cone. Group mean change differences (MCD) were compared using independent sample t-tests. Fisher's exact tests were used to determine group differences in the proportion of subjects that displayed earlier activation responses post-training.

RESULTS

Group 1 MCD revealed earlier gluteus maximus, gluteus medius, rectus femoris, medial hamstrings, and biceps femoris activation timing than Group 2 (P ≤ 0.006) and more Group 1 subjects displayed earlier activation of these muscles post-training (P ≤ 0.041). Group 1 MCD also revealed earlier peak resultant GRF timing and improved "kick quickness" than Group 2 (P ≤ 0.014) and more Group 1 subjects displayed earlier response timing for these variables post-training (P = 0.035).

CONCLUSION

Progressive resistance, whole body long-axis rotational training may improve performance during sports movements that require quick, integrated trunk-lower extremity function.

Supplemental bio-tenodesis improves tibialis anterior allograft yield load in extremely low density tibiae

INTRODUCTION

Improved soft tissue tendon graft mechanical properties have led to their increased use for anterior cruciate ligament (ACL) reconstruction. Because they do not have an osseous component; however, there are greater concerns regarding tibial graft slippage during early postoperative rehabilitation and activities of daily living, particularly in patients with poor bone mineral density (BMD), such as older patients, women, smokers, and patients undergoing revision ACL reconstruction surgery.

METHODS

This in vitro biomechanical study attempted to determine the effectiveness of supplemental ACL graft fixation in low BMD tibiae. Eight paired knees (16 specimens) were harvested from female cadavers (mean age = 76, range = 60-88 years). Tibiae were assigned to either a combination bioabsorbable interference screw, bio-tenodesis screw group (Group 1, n = 8, apparent BMD = 0.44 ± 0.13 g/cm(2)) or a bioabsorbable interference screw group (Group 2, n = 8, apparent BMD = 0.44 ± 0.14 g/cm(2)). Double-strand (single loop) tibialis anterior tendon allografts were fixed in matched diameter tibial tunnels. Using a custom 6° of freedom jig, potted constructs were mounted on to a servo hydraulic device with the axial loading force aligned directly with the tibial tunnel. Constructs underwent progressive cyclic tensile loading from 10 to 150 N with a 25 N load increase every 20 cycles. This was followed by yield load to failure testing (20 mm/min).

RESULTS

Groups did not display displacement differences during progressive cyclic loading. Group 1 (312.7 ± 67.5 N) displayed 25% greater yield load at failure than Group 2 (235.0 ± 47.6 N), P = 0.045. Both groups displayed fixation levels well below the previously reported minimal safe threshold estimate for early unrestricted weight bearing, accelerated rehabilitation and activities of daily living.

CONCLUSION

Supplemental bio-tenodesis fixation may improve early tibial-soft tissue tendon graft fixation in patients that have poor tibial BMD, but study results suggest that both methods may require weightbearing, rehabilitation, and activity of daily living restrictions during the early postoperative period to prevent graft slippage.

Whole body, long-axis rotational training improves lower extremity neuromuscular control during single leg lateral drop landing and stabilization

BACKGROUND

Poor neuromuscular control during sports activities is associated with non-contact lower extremity injuries. This study evaluated the efficacy of progressive resistance, whole body, long-axis rotational training to improve lower extremity neuromuscular control during a single leg lateral drop landing and stabilization.

METHODS

Thirty-six healthy subjects were randomly assigned to either Training or Control groups. Electromyographic, ground reaction force, and kinematic data were collected from three pre-test, post-test trials. Independent sample t-tests with Bonferroni corrections for multiple comparisons were used to compare group mean change differences (P≤0.05/21≤0.0023).

FINDINGS

Training group gluteus maximus and gluteus medius neuromuscular efficiency improved 35.7% and 31.7%, respectively. Training group composite vertical-anteroposterior-mediolateral ground reaction force stabilization timing occurred 1.35s earlier. Training group knee flexion angle at landing increased by 3.5°. Training group time period between the initial two peak frontal plane knee displacements following landing increased by 0.17s. Training group peak hip and knee flexion velocity were 21.2°/s and 20.1°/s slower, respectively. Time period between the initial two peak frontal plane knee displacements following landing and peak hip flexion velocity mean change differences displayed a strong relationship in the Training group (r(2)=0.77, P=0.0001) suggesting improved dynamic frontal plane knee control as peak hip flexion velocity decreased.

INTERPRETATION

This study identified electromyographic, kinematic, and ground reaction force evidence that device training improved lower extremity neuromuscular control during single leg lateral drop landing and stabilization. Further studies with other populations are indicated.

Femoral cross-pin safety in anterior cruciate ligament reconstruction as a function of femoral tunnel position and insertion angle

PURPOSE

To compare femoral cross-pin guidewire insertion at differing angles to identify "safe zones" relative to saphenous nerve, popliteus tendon, fibular collateral ligament, peroneal nerve, and femoral artery/vein locations between transtibial and medial-portal femoral tunnel drilling methods.

METHODS

Five paired cadaveric knees were randomly assigned to a transtibial or medial-portal femoral (anatomic) tunnel drilling group. Guidewires were inserted at differing frontal plane angles (+10°, 0°, -10°, and -20°). Distances between the guidewire and the anatomic structure of interest were measured with an electronic caliper.

RESULTS

Two-way analysis of variance showed that guidewire angle, not tunnel drilling method, created significant differences between guidewire-saphenous nerve (P < .001) and guidewire-femoral artery/vein (P < .001) distances. The +10° angle showed a shorter guidewire-saphenous nerve distance than the 0°, -10°, and -20° angles. The +10° angle also showed a shorter guidewire-femoral artery/vein distance than the -10° and -20° angles, and the 0° insertion angle created a shorter guidewire-femoral artery/vein distance than the -10° and -20° angles. Fisher exact tests showed that guidewires inserted at a +10° angle showed a greater incidence of safe-zone violations for the saphenous nerve (P = .04) and femoral artery/vein (P < .0001).

CONCLUSIONS

Insertion angle, not tunnel drilling method, influenced saphenous nerve and femoral artery/vein injury risk. At the +10° angle, the saphenous nerve and femoral artery/vein are at greater risk for surgically induced injury. Guidewire insertion at -10° or -20° angles should increase concerns about potential popliteus tendon and fibular collateral ligament injury.

CLINICAL RELEVANCE

Insertion angle, not tunnel drilling method, influenced saphenous nerve and femoral artery/vein injury risk.

Total knee arthroplasty in motivated patients with knee osteoarthritis and athletic activity approach type goals: a conceptual decision-making model

Knee osteoarthritis is one of the most common disabling medical conditions. With longer life expectancy the number of total knee arthroplasty (TKA) procedures being performed worldwide is projected to increase dramatically. Patient education, physical activity, bodyweight levels, expectations and goals regarding the ability to continue athletic activity participation are also increasing. For the subset of motivated patients with knee osteoarthritis who have athletic activity approach type goals, early TKA may not be the best knee osteoarthritis treatment option to improve satisfaction, quality of life and outcomes. The purpose of this clinical commentary is to present a conceptual decision-making model designed to improve the knee osteoarthritis treatment intervention outcome for motivated patients with athletic activity approach type goals. The model focuses on improving knee surgeon, patient and rehabilitation clinician dialogue by rank ordering routine activities of daily living and quality of life evoking athletic activities based on knee symptom exacerbation or re-injury risk. This process should help establish realistic patient expectations and goals for a given knee osteoarthritis treatment intervention that will more likely improve self-efficacy, functional independence, satisfaction and outcomes while decreasing the failure risk associated with early TKA.

Biomechanical comparison of screw-in suture anchor-suture combinations used for Bankart repair

INTRODUCTION

Bankart repair laxity may contribute to pathologic joint instability. This biomechanical study compared two screw-in suture anchor-suture combinations under tensile loads.

METHODS

Twelve pairs of scapulae were implanted with either a 3 mm diameter, 14 mm long poly-L/D-lactide suture anchor with a suture eyelet (Group 1) or a 3.1 mm diameter, 11 mm long polylactide suture anchor with a molded eyelet (Group 2). Constructs were cyclically loaded between 25 and 50 N with a 25 N load increase every 25 cycles.

RESULTS

Group 2 displayed greater displacement at failure, had more specimens with > or =2 mm displacement by the 50 N interval (P = 0.014), and had displaced more by 100 N (P < or = 0.046). Group 1 displayed a stronger load-displacement at failure relationship than Group 2 (r (2) = 0.67 vs. r (2) = 0.37).

CONCLUSION

Construct differences may influence decisions regarding the required number of suture anchor-suture loops, the rehabilitation timetable, and the timing of return to unrestricted activities.

Racial differences in ischemic cerebrovascular disease

PURPOSE

To evaluate racial differences in extracranial carotid atherosclerosis and vascular risk factors in patients with symptomatic cerebrovascular disease.

BACKGROUND

There are conflicting data on racial differences in certain vascular risk factors and prevalence of large-vessel versus small-vessel disease in patients with stroke.

METHODS

We prospectively studied 211 consecutive patients admitted to our stroke service. There were 71 African-American, 114 Caucasian, 20 Hispanic, and 6 other patients. Extracranial vascular stenosis was assessed with a carotid duplex (CD) scan. Risk factors monitored included race, age, history of hypertension (HTN), diabetes mellitus (DM), prior stroke, hyperlipidemia, smoking, cardiac disease (congestive heart failure, atrial fibrillation), and family history of stroke. Cholesterol and triglyceride blood levels, and computed tomography/magnetic resonance imaging results were obtained in most cases.

RESULTS

Significant differences were found between Caucasians and African-Americans in several variables. Caucasians had more frequent hypertriglyceridemia and a higher rate of cardiac disease. African-Americans had more frequent lacunar infarcts. There was a trend toward decreased risk of CD scan abnormality, and more HTN and prior stroke in African-Americans. There were no differences in the presence of DM, both HTN and DM, abnormal cholesterol (including high- and low-density lipoprotein) values, and smoking history. Except for the difference in lacunar infarction, there were no differences in the type of stroke.

CONCLUSIONS

Our data indicate a greater risk of cardiac disease and hypertriglyceridemia in Caucasians with cerebrovascular disease. There was a trend for Caucasians to have more extracranial carotid disease, and a trend for African-Americans to have more hypertension and prior stroke, although the difference did not reach significance. Consistent with prior racial studies, we found African-Americans to have more lacunar strokes than Caucasians.

Comparison of perioperative complications in patients with and without rheumatoid arthritis who receive total elbow replacement

Total elbow replacement is a well-recognized surgical treatment for patients with advanced rheumatoid arthritis (RA) of the elbow. At present, there is minimal literature outlining the perioperative complications associated with total elbow replacement. We endeavored to identify complication rates and hospital disposition differences between patients with and without RA who received a total elbow replacement. Data from the Nationwide Inpatient Sample was used to capture 3,617 patients who received a total elbow arthroplasty between 1988-2005. Of these, 888 had a primary diagnosis of RA and were compared against patients without RA. Analyses addressed perioperative complications and hospital disposition factors, such as charges and length of stay. Overall complication rates were very low with only 2 variables, respiratory complications (P = .01) and renal failure (P = .04) demonstrating significantly worse outcomes in patients without RA (P = .01). Patients without RA had also had longer lengths of stay (P < 0.01). There were 9 reported perioperative deaths. The findings suggest that the perioperative complications of a total elbow replacement for all patients studied are few and that outcomes in patients with RA are nearly equivalent to those in patients without RA.

Biomechanical comparison between CentraLoc and Intrafix fixation of quadrupled semitendinosus-gracilis allografts in cadaveric tibiae with low bone mineral density

Supplementary or back-up tibial tunnel fixation of a quadruple semitendinosus-gracilis (STG) graft is often performed when the knee surgeon questions the integrity of intra-tunnel fixation. Back-up fixation devices such as staples however may contribute to increased knee pain and dysfunction. Both primary extra-tunnel and intra-tunnel fixation devices may provide sufficient quadruple STG graft fixation in a tibial tunnel to preclude the need for back-up fixation. This biomechanical study compared the fixation of quadruple STG allografts in standard drilled tunnels prepared in low apparent bone mineral density (BMD) cadaveric tibiae using either an Intrafix device with primary intra-tunnel fixation in a region of predominantly cancellous trabecular bone, or a CentraLoc device with primary extra-tunnel fixation in a region of predominantly cortical bone. The study hypothesis was that the CentraLoc device would display superior fixation in these low apparent BMD cadaveric tibiae. Matched pair tibiae and quadruple STG allografts were divided into two groups of seven specimens each. Extraction drilled tunnels matched allograft diameter. Constructs were pretensioned on a servo hydraulic device between 10 and 50 N for 10 cycles and isometric pretensioned at 50 N for 1 min prior to undergoing 500 loading cycles (50-250 N) and load to failure testing (20 mm/min). The CentraLoc group displayed superior load at failure (448.4+/-171 N vs. 338.4+/-119 N, P=0.04) and survived more loading cycles (410+/-154 cycles vs. 196+/-230 cycles, P=0.04) than the Intrafix group. Most CentraLoc group specimens (6/7, 85.7%) failed by device pullout with intact quadruple STG allograft strands while all Intrafix group specimens (7/7, 100%) failed by slippage of one or more strands (P=0.005).

Three-dimensional mapping of temporo-limbic regions and the lateral ventricles in schizophrenia: gender effects

BACKGROUND

Local alterations in morphological parameters are poorly characterized in several brain regions widely implicated in schizophrenia neuropathology.

METHODS

Surface-based anatomical modeling was applied to magnetic resonance data to obtain three-dimensional (3D) average anatomical maps and measures of location, shape, asymmetry, and volume for the lateral ventricles, hippocampus, amygdala, and superior temporal gyrus in schizophrenic (n = 25; 15 male) and normal subjects (n = 28; 15 male) matched for demographic variables. For all regions, intra-group variability was visualized and group differences assessed statistically to discriminate local alterations in anatomy across sex and diagnosis.

RESULTS

Posterior hippocampal volumes, lengths, and widths were reduced in patients. The right amygdala showed volume increases in schizophrenia patients versus controls. Ventricular enlargements, pronounced in the left hemisphere, occurred in the superior and lateral dimensions in patients, and these effects interacted with gender. Superior horn anterior extremes, inferior horn volumes, and hippocampal asymmetries exhibited gender effects. Significant group differences were absent in superior temporal gyrus parameters. Finally, regional variability profiles differed across groups.

CONCLUSIONS

Clear morphometric differences of the lateral ventricles, hippocampus, and amygdala indicate regional displacements and shape distortions in several functional systems in schizophrenia. Alterations in these structures as mapped in 3D may provide the foundation for establishing brain abnormalities not previously defined at such a local level.

DsbD-catalyzed transport of electrons across the membrane of Escherichia coli

Dsb proteins catalyze folding and oxidation of polypeptides in the periplasm of Escherichia coli. DsbC reduces wrongly paired disulfides by transferring electrons from its catalytic dithiol motif (98)CGYC. Genetic evidence suggests that recycling of this motif requires at least three proteins, the cytoplasmic thioredoxin reductase (TrxB) and thioredoxin (TrxA) as well as the DsbD membrane protein. We demonstrate here that electrons are transferred directly from thioredoxin to DsbD and from DsbD to DsbC. Three cysteine pairs within DsbD undergo reversible disulfide rearrangements. Our results suggest a novel mechanism for electron transport across membranes whereby electrons are transferred sequentially from cysteine pairs arranged in a thioredoxin-like motif (CXXC) to a cognate reactive disulfide.

[The seat belt: effect on the consequences of traffic accidents (author's transl)]

At the present time, more than 90% of the motor vehicles in the Federal Republic of Germany are equipped with seat belts. On the average, however, only one out of two drivers uses his belt. It has been established that the seat belt, considering the present rate of use, annually protects about 1700 car occupants from fatality and about 30,000 from injuries (resulting in economic savings of approx. DM 1.8 X 10(9)). If all car occupants were to observe seat-belt regulations, this gain in safety might be doubled. Experience of other countries indicates that the introduction of the fine would result in much better compliance with the regulation than has been observed thus far.