The effect of subscapularis-specific rehabilitation following total shoulder arthroplasty: a prospective, double-blinded, randomized controlled trial.

BACKGROUND: Patients undergoing a total shoulder arthroplasty (TSA) through a deltopectoral approach will require repair of the subscapularis tendon. There are no universal postoperative guidelines for rehabilitation of the subscapularis specifically. We hypothesize that the addition of a subscapularis-specific regimen will result in improved subscapularis strength and function. METHODS: Adult patients undergoing anatomic TSA for the treatment of primary glenohumeral osteoarthritis were included. Patients were randomized into either the traditional rehabilitation (TR) control group or the subscapularis rehabilitation (SR) group, which consisted of the traditional therapy along with early and additional subscapularis exercises. Baseline demographics, patient-reported outcome measures (PROMs), range of motion (ROM), provocative tests, and subscapularis strength using a handheld dynamometer were measured preoperatively at the initial clinic visit (ICV) as well as 3 months, 6 months, and 1 year postoperatively. The primary outcome of interest was a comparison of subscapularis strength between cohorts relative to preoperative baseline, whereas secondary outcomes were functional, ROM, and PROMs. RESULTS: Sixty-six patients were included in the final analysis (32 TR vs. 34 SR). There were no statistically significant differences between cohorts at the ICV with regard to demographics, baseline subscapularis strength, functional testing, or PROMs. All postoperative time points demonstrated similar subscapularis strength testing between TR and SR groups (P > .05). Additionally, peak and average subscapularis strength testing at 3, 6, and 12 months postoperatively were similar to baseline ICV testing in both groups. Both groups demonstrated improvements across several provocative tests, ROM, and PROM outcome metrics at every postoperative time point as compared to baseline ICV values (P < .05). CONCLUSIONS: Patients undergoing anatomic TSA return to baseline internal rotation strength by 3 months postoperatively and demonstrate significant improvements in function, ROM, and several patient-reported outcome measures. The addition of early and focused subscapularis strengthening exercises does not appear to significantly impact any outcomes when compared to traditional rehabilitation programs.

Association of Prior Anterior Cruciate Ligament Tear With Decreased Career Longevity in Women's National Basketball Association.

BACKGROUND: The incidence of anterior cruciate ligament (ACL) injuries in women's basketball exceeds that of men. There is a paucity of data regarding career performance in Women's National Basketball Association (WNBA) athletes with a history of ACL reconstruction. PURPOSE: To determine whether WNBA athletes with a history of ACL injury prior to professional play have reduced career game utilization, defined as games played and started and minutes per game (MPG), as well as statistical performance, defined by player efficiency rating (PER). STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: Included were 42 WNBA players from 1997 to 2018 who had a history of ACL reconstruction before entering professional leagues. Body mass index (BMI), age, and position were collected for each player. Career data and performance statistics were likewise collected for each player's entire WNBA career. A control group of WNBA players with no history of ACL injury were matched by position, BMI, and age at the time of WNBA debut. Statistics compared game utilization and performance to assess the impact of ACL reconstruction. RESULTS: Athletes who sustained an ACL tear before entering the league played in fewer games per season in their first 3 professional seasons compared with healthy controls (24.2 ± 8.4 vs 28.2 ± 6.1; P = .02). Among athletes with a history of ACL reconstruction, 11 (26.2%) played only a single WNBA season, while no control athletes played in just 1 season. Additionally, athletes who had a previous ACL tear started significantly fewer games per season (9.0 ± 9.4 vs 14.0 ± 9.0; P < .01) and played fewer MPG (15.5 ± 7.2 vs 20.7 ± 5.5; P < .01) during their WNBA career. Athletes with a history of ACL tear had significantly shorter WNBA careers (4.8 ± 4.1 vs 8.1 ± 3.3 seasons; P < .001). Total professional play duration (WNBA + overseas) was significantly reduced in players with an ACL tear compared with controls (P < .05). PER was not significantly different between cohorts at any time point. CONCLUSION: WNBA athletes with a history of an ACL tear before professional play had decreased career game utilization and workload throughout their career despite having similar PER compared with healthy controls.

Effect of Achilles Tendon Rupture on Player Performance and Longevity in Women's National Basketball Association Players.

BACKGROUND: Women's National Basketball Association (WNBA) players have a greater incidence of lower extremity injury compared with male players, yet no data exist on functional outcomes after Achilles tendon rupture (ATR). PURPOSE: To evaluate the effect of Achilles tendon repair on game utilization, player performance, and career longevity in WNBA athletes. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: WNBA players from 1997 to 2019 with a history of ATR (n = 12) were matched 1:2 to a healthy control group. Player characteristics, game utilization, and in-game performance data were collected for each athlete, from which the player efficiency rating (PER) was calculated. Statistical analysis was performed comparing postinjury data to preinjury baseline as well as cumulative career data. Changes at each time point relative to the preinjury baseline were also compared between groups. RESULTS: Of the 12 players with ATR, 10 (83.3%) returned to play at the WNBA level at a mean (±SD) of 12.5 ± 3.3 months. Four players participated in only 1 WNBA season after injury. There were no differences in characteristics between the 10 players who returned to play after injury and the control group. After return to play, the WNBA players demonstrated a significant decrease in game utilization compared with preinjury, playing in 6.0 ± 6.9 fewer games, starting in 12.7 ± 15.4 fewer games, and playing 10.2 ± 9.1 fewer minutes per game (P < .05 for all). After the index date of injury, the players with Achilles repair played 2.1 ± 1.2 more years in the WNBA, while control players played 5.35 ± 3.2 years (P < .01) Additionally, the players with Achilles repair had a significant decrease in PER in the year after injury compared with preinjury (7.1 ± 5.3 vs 11.0 ± 4.4; P = .02). The reduction in game utilization and decrease in PER in these players was maintained when compared with the matched controls (P < .05 for both). CONCLUSION: The majority of WNBA players who sustained ATR were able to return to sport after their injury; however, their career longevity was shorter than that of healthy controls. There was a significant decrease in game utilization and performance in the year after return to play compared with healthy controls.

Elbow Torque Is Reduced in Asymptomatic College Pitchers With Elbow Laxity: A Dynamic Ultrasound Study.

PURPOSE: To determine the relation between medial elbow torque, as measured by wearable sensor technology, and adaptations of the medial elbow structures on dynamic ultrasound imaging in asymptomatic collegiate pitchers. METHODS: Thirty-four pitchers from National Collegiate Athletic Association Division II universities were eligible for preseason testing. The exclusion criteria included age younger than 18 years, history of surgery, non-pitcher, or current restrictions. Pitchers were fitted with a wearable sensor sleeve that recorded elbow torque, arm slot, arm speed, and arm rotation. Pitchers threw 5 fastballs in a standardized manner off the mound at game-speed effort. They also underwent dynamic ultrasound imaging of the elbow by a musculoskeletal sonographer, with standardized valgus loading. Images were deidentified, and measurements of the ulnar collateral ligament (UCL) and ulnohumeral joint space (UHJS), to assess elbow laxity, were performed by a musculoskeletal radiologist. RESULTS: The final analysis included 28 pitchers with an average age of 20.1 years (standard deviation, 1.3 years; range, 18-23 years) and playing experience of 15.3 years (standard deviation, 1.8 years; range, 11-19 years). The dominant UCL thickness (P < .001), loaded UHJS (P = .039), and delta UHJS (P < .001) were significantly greater than the nondominant measurements. An inverse correlation was found between loaded UHJS and medial elbow torque (r = -0.4, P < .001). Additionally, every 1-mm increase in UHJS significantly reduced medial elbow torque by 2.27 Nm (P = .032) and arm slot by 8.8° (P = .019) and increased arm rotation by 5.3° (P = .043). Pitchers with a loaded UHJS of 4.4 mm or greater and delta UHJS of 1.25 mm or greater had significantly reduced medial elbow torque (P < .001). Pitchers with a UCL thickness of 1.65 mm or greater had significantly increased medial elbow torque (47.4 Nm vs 44.8 Nm, P = .006). CONCLUSIONS: Pitchers with increased dynamic elbow laxity were found to experience reduced medial elbow torque while pitching. Additionally, pitchers with greater UCL thickness on ultrasound were found to experience increased medial elbow torque while pitching. This study's findings suggest a relation between anatomic adaptations found on ultrasound of the pitching elbow and medial elbow torque. LEVEL OF EVIDENCE: Level II, prospective cohort study.

Diagnostic accuracy of ultrasound for rotator cuff tears.

Ultrasonography (US) is an inexpensive, convenient, and effective tool that can be used to evaluate the shoulder. It does not expose the patient to harmful radiation and can be used to evaluate the musculoskeletal system dynamically. Additionally, US is not subject to metal artifacts when evaluating patients with previously placed hardware. Over the years, US has been found to be reliable and accurate for diagnosing rotator cuff tears (RCTs), despite its operatordependence. The usage of US for diagnosing RCTs in orthopedic practice varies depending on practitioners' familiarity with the exam and the availability of experienced technicians. The purpose of this article is to review the diagnostic accuracy of US for identifying RCTs.

Pain After Anatomic Total Shoulder Arthroplasty Versus Reverse Total Shoulder Arthroplasty.

As anatomic total shoulder arthroplasty (aTSA) and reverse total shoulder arthroplasty (rTSA) become increasingly common, differences between the 2 procedures are of importance. The purpose of this study was to determine differences in acute pain levels between patients undergoing aTSA and rTSA. Sixty patients undergoing aTSA or rTSA were assessed for participation. The primary outcome was postoperative daily visual analog scale scores, which were initially collected for 4 days postoperatively. Secondary outcomes included opioid consumption, length of stay, and complications. Comparisons between the 2 groups were assessed using a multivariable analysis, which controlled for sex, age, body mass index, and type of anesthetic. A total of 57 patients consented and were analyzed. No significant differences were found in postoperative visual analog scale scores in the first 4 days following surgery or at 1 year postoperatively. Patients undergoing aTSA had a higher mean opioid requirement in the first 4 hours postoperatively (1.0±0.7 vs 0.4±0.6 morphine milligram equivalents, P<.01). Forty percent of patients undergoing shoulder arthroplasty were prescribed narcotics within the 3 months prior to surgery. Patients who were prescribed narcotics prior to surgery were more likely to continue to require narcotics at extended time periods postoperatively. Patients undergoing aTSA required more opioid medication in the immediate postoperative period. However, after 4 hours postoperatively, no significant differences in pain scores or opioid consumption were found. These findings suggest that patients undergoing aTSA or rTSA have similar postoperative pain profiles. Patients who are prescribed narcotics before shoulder arthroplasty are at an increased risk for postoperative opioid demand. [Orthopedics. 2019; 42(2):e247-e252.].

The Effect of Intraoperative Hypothermia on Shoulder Arthroplasty.

Limited evidence is available regarding the correlation between intraoperative hypothermia and perioperative complications in shoulder arthroplasty. The purpose of this study was to determine the incidence of intraoperative hypothermia in patients treated with shoulder arthroplasty and its effect on perioperative complications. A retrospective chart review was performed on 657 consecutive patients who underwent shoulder arthroplasty at a single institution between August 2013 and June 2016. Demographic data, surgery-specific data, postoperative complications, length of stay, and 30-day read-mission were recorded. Patients were classified as hypothermic if their mean intraoperative temperature was less than 36°C. Statistical analyses with univariate and multivariate logistic regression were performed to evaluate the association of intraoperative hypothermia with perioperative complications. The incidence of intraoperative hypothermia in shoulder arthroplasty was 52.7%. Increasing age (P=.002), lower body mass index (P=.006), interscalene anesthetic (P=.004), and lower white blood cell count (P<.001) demonstrated increased association with hypothermia. Longer operating room times and increased estimated blood loss were not found to be associated with intraoperative hypothermia. Hypothermia demonstrated no significant association with surgical site infections nor any other perioperative complications. Patients undergoing shoulder arthroplasty showed a high incidence of intraoperative hypothermia. Lower body mass index, increasing age, interscalene anesthetic, and lower white blood cell count were associated with an increased incidence of hypothermia. Contrary to previous studies, intraoperative hypothermia was not found to contribute to perioperative complications in shoulder arthroplasty. [Orthopedics. 2018; 41(4):e523-e528.].

Inguinal Hernia in Athletes: Role of Dynamic Ultrasound.

BACKGROUND: Inguinal hernia is a commonly encountered cause of pain in athletes. Because of the anatomic complexity, lack of standard imaging, and the dynamic condition, there is no unified opinion explaining its underlying pathology. HYPOTHESIS: Athletes with persistent groin pain would have a high prevalence of inguinal hernia with dynamic ultrasound, and herniorrhaphy would successfully return athletes to activity. STUDY DESIGN: Case-control study. LEVEL OF EVIDENCE: Level 3. METHODS: Forty-seven amateur and professional athletes with sports-related groin pain who underwent ultrasound were selected based on history and examination. Patients with prior groin surgery or hip pathology were excluded. Clinical and surgical documentation were correlated with imaging. The study group was compared with 41 age-matched asymptomatic athletes. RESULTS: Ultrasound was positive for hernia with movement of bowel, bladder, or omental tissue anterior to the inferior epigastric vessels during Valsalva maneuver. The 47-patient symptomatic study group included 41 patients with direct inguinal hernias, 1 with indirect inguinal hernia, and 5 with negative ultrasound. Of 42 patients with hernia, 39 significantly improved with herniorrhaphy, 2 failed to improve after surgery and were diagnosed with adductor longus tears, and 1 improved with physical therapy. Five patients with negative ultrasound underwent magnetic resonance imaging and were diagnosed with hip labral tear or osteitis pubis. The 41-patient asymptomatic control group included 3 patients with direct inguinal hernias, 2 with indirect inguinal hernias, and 3 with femoral hernias. CONCLUSION: Inguinal hernias are a major component of groin pain in athletes. Prevalence of direct inguinal hernia in symptomatic athletes was greater than that for controls ( P < 0.001). Surgery was successful in returning these athletes to sport: 39 of 42 (93%) athletes with groin pain and inguinal hernia became asymptomatic. CLINICAL RELEVANCE: Persistent groin pain in the athlete may relate to inguinal hernia, which can be diagnosed with dynamic ultrasound imaging. Herniorrhaphy is successful at returning athletes to sports activity.

Liposomal bupivacaine versus interscalene nerve block for pain control after shoulder arthroplasty: a prospective randomized trial.

HYPOTHESIS: Our hypothesis was that in patients undergoing shoulder arthroplasty, a prospective randomized trial would find no significant differences in average daily pain scores of those treated with interscalene nerve block (INB) vs. local liposomal bupivacaine (LB). METHODS: Sixty patients undergoing primary shoulder arthroplasty were assessed for eligibility. Study arms included either intraoperative local infiltration of LB (20 mL bupivacaine/20 mL saline) or preoperative INB, with a primary outcome of postoperative average daily visual analog scale scores for 4 days. Secondary outcomes assessed included opioid consumption, length of stay, and complications. Randomization was by a computerized algorithm. Only the observer was blinded to the intervention. RESULTS: Three patients were excluded, all before randomization. A total of 57 patients were analyzed. Outcomes showed a significant increase in pain in the LB group between 0 and 8 hours postoperatively (mean [standard deviation] 5.3 [2.2] vs. 2.5 [3.0]; P = .001). A significant increase in intravenous morphine equivalents was found in the INB group at 13 to 16 hours (mean [standard deviation] 1.2 [0.9] vs. 0.6 [0.7]; P = .01). No significant differences were found in any variable after postoperative day 0 between the 2 groups. CONCLUSION: An increase in early postoperative pain on the day of surgery was found with LB, whereas the INB group required more narcotics at the end of the day. After the day of surgery, there were no significant differences found in any variables. These findings suggest that LB provides similar overall pain relief as INB, with no increase in complications or length of stay and a decrease in narcotic requirements on the day of surgery.

Pain Assessment After Anterior Cruciate Ligament Reconstruction: Bone-Patellar Tendon-Bone Versus Hamstring Tendon Autograft.

BACKGROUND: Anterior cruciate ligament (ACL) reconstruction is a common outpatient procedure that is accompanied by significant postoperative pain. PURPOSE: To determine differences in acute pain levels between patients undergoing ACL reconstruction with bone-patellar tendon-bone (BTB) versus hamstring tendon (HS) autograft. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: A total of 70 patients who underwent primary ACL reconstruction using either BTB or HS autografts consented to participate. The primary outcome of the study was postoperative pain levels (visual analog scale), which were collected immediately after surgery and for 3 days postoperatively. Secondary outcome measures included opioid consumption (intravenous morphine equivalents), hours slept, patient satisfaction, reported breakthrough pain, and calls to the physician. RESULTS: Patients treated with BTB had increased pain when compared with those treated with HS in the acute postoperative period (mean ± SD: day 0, 6.0 ± 1.7 vs 5.2 ± 2.0 [P = .066]; day 1, 5.9 ± 1.7 vs 4.9 ±1.7 [P = .024]; day 2, 5.2 ± 1.9 vs 4.1 ± 2.0 [P = .032]; day 3, 4.8 ± 2.1 vs 3.9 ± 2.3 [P = .151]). There were also significant increases in reported breakthrough pain (day 0, 76% vs 43% [P = .009]; day 1, 64% vs 35% [P = .003]) and calls to the physician due to pain (day 1, 19% vs 0% [P = .041]) in the BTB group. There were no significant differences in narcotic requirements or sleep disturbances. Overall, the BTB group reported significantly less satisfaction with pain management on days 0 and 1 (P = .024 and .027, respectively). CONCLUSION: A significant increase in acute postoperative pain was found when performing ACL reconstruction with BTB compared with HS. Patients treated with BTB were more likely to have breakthrough pain, decreased satisfaction with their pain management, and to contact their physician due to pain. These findings suggest a difference in early postoperative pain between the 2 most common graft options for ACL reconstruction. Patients should be informed of the differences in acute postoperative pain when deciding on graft choice with their physician.

Meniscal allograft transplantation. Part 1: systematic review of graft biology, graft shrinkage, graft extrusion, graft sizing, and graft fixation.

PURPOSE: To provide a systematic review of the literature regarding five topics in meniscal allograft transplantation: graft biology, shrinkage, extrusion, sizing, and fixation. METHODS: A systematic literature search was conducted using the PubMed (MEDLINE), ScienceDirect, and EBSCO-CINAHL databases. Articles were classified only in one topic, but information contained could be reported into other topics. Information was classified according to type of study (animal, in vitro human, and in vivo human) and level of evidence (for in vivo human studies). RESULTS: Sixty-two studies were finally included: 30 biology, 3 graft shrinkage, 11 graft extrusion, 17 graft size, and 6 graft fixation (some studies were categorized in more than one topic). These studies corresponded to 22 animal studies, 22 in vitro human studies, and 23 in vivo human studies (7 level II, 10 level III, and 6 level IV). CONCLUSIONS: The principal conclusions were as follows: (a) Donor cells decrease after MAT and grafts are repopulated with host cells form synovium; (b) graft preservation alters collagen network (deep freezing) and causes cell apoptosis with loss of viable cells (cryopreservation); (c) graft shrinkage occurs mainly in lyophilized and gamma-irradiated grafts (less with cryopreservation); (d) graft extrusion is common but has no clinical/functional implications; (e) overall, MRI is not superior to plain radiograph for graft sizing; (f) graft width size matching is more important than length size matching; (g) height appears to be the most important factor influencing meniscal size; (h) bone fixation better restores contact mechanics than suture fixation, but there are no differences for pullout strength or functional results; and (i) suture fixation has more risk of graft extrusion compared to bone fixation. LEVEL OF EVIDENCE: Systematic review of level II-IV studies, Level IV.

Meniscal allograft transplantation. Part 2: systematic review of transplant timing, outcomes, return to competition, associated procedures, and prevention of osteoarthritis.

PURPOSE: To provide a systematic review of the literature regarding five topics in meniscal allograft transplantation (MAT): optimal timing for transplantation, outcomes, return to competition, associated procedures, and prevention of osteoarthritis. METHODS: A systematic literature search was conducted using the PubMed (MEDLINE), ScienceDirect, and EBSCO-CINAHL databases. Articles were classified only in one topic, but information contained could be reported into other topics. Information was classified according to type of study (animal, in vitro human, and in vivo human) and level of evidence (for in vivo human studies). Specific inclusion criteria were determined for the outcomes and prevention of osteoarthritis topics. RESULTS: Twenty-four studies were finally included: two optimal timing, seven outcomes, three return to competitive sport, 16 MAT and associated procedures, and 5 MAT and prevention of osteoarthritis (some studies were categorized in more than one topic). These studies corresponded to 2 animal studies and 31 in vivo human studies (1 level II, 1 level III, and 29 level IV). CONCLUSIONS: The principal conclusions were as follows: (a) there is no evidence to support that MAT has to be performed at the same time or immediately after meniscectomy to prevent development of postmeniscectomy syndrome; (b) MAT successfully improves symptoms, function, and quality of life at 7-to-14 years of follow-up (level IV evidence); (c) the overall failure rate (need for knee arthroplasty) is 10-29% at long-term follow-up; (d) MAT allows return to same level of competition in 75-85% of patients at short- to mid-term follow-up (only three studies level IV evidence with small sample size); (e) associated cartilage procedures or anterior cruciate ligament reconstruction to MAT does not worsen the results; (f) MAT may prevent progression of cartilage damaged at long-term follow-up, but may not prevent degeneration in previously healthy cartilage. LEVEL OF EVIDENCE: Systematic review of level II-IV studies, Level IV.

In vivo shoulder function after surgical repair of a torn rotator cuff: glenohumeral joint mechanics, shoulder strength, clinical outcomes, and their interaction.

BACKGROUND: Surgical repair of a torn rotator cuff is based on the belief that repairing the tear is necessary to restore normal glenohumeral joint (GHJ) mechanics and achieve a satisfactory clinical outcome. HYPOTHESIS: Dynamic joint function is not completely restored by rotator cuff repair, thus compromising shoulder function and potentially leading to long-term disability. STUDY DESIGN: Controlled laboratory study and Case series; Level of evidence, 4. METHODS: Twenty-one rotator cuff patients and 35 control participants enrolled in the study. Biplane radiographic images were acquired bilaterally from each patient during coronal-plane abduction. Rotator cuff patients were tested at 3, 12, and 24 months after repair of a supraspinatus tendon tear. Control participants were tested once. Glenohumeral joint kinematics and joint contact patterns were accurately determined from the biplane radiographic images. Isometric shoulder strength and patient-reported outcomes were measured at each time point. Ultrasound imaging assessed rotator cuff integrity at 24 months after surgery. RESULTS: Twenty of 21 rotator cuff repairs appeared intact at 24 months after surgery. The humerus of the patients' repaired shoulder was positioned more superiorly on the glenoid than both the patients' contralateral shoulder and the dominant shoulder of control participants. Patient-reported outcomes improved significantly over time. Shoulder strength also increased over time, although strength deficits persisted at 24 months for most patients. Changes over time in GHJ mechanics were not detected for either the rotator cuff patients' repaired or contralateral shoulders. Clinical outcome was associated with shoulder strength but not GHJ mechanics. CONCLUSION: Surgical repair of an isolated supraspinatus tear may be sufficient to keep the torn rotator cuff intact and achieve satisfactory patient-reported outcomes, but GHJ mechanics and shoulder strength are not fully restored with current repair techniques. CLINICAL RELEVANCE: The study suggests that current surgical repair techniques may be effective for reducing pain but have not yet been optimized for restoring long-term shoulder function.

Tibiofemoral joint kinematics of the anterior cruciate ligament-reconstructed knee during a single-legged hop landing.

BACKGROUND: Abnormal 3-dimensional tibiofemoral joint kinematics have been identified in anterior cruciate ligament-reconstructed knees during functional gait tasks, which is suggested to directly affect risk of knee osteoarthritis. However, the extent to which similar high-risk abnormalities are present during more demanding maneuvers, such as single-legged hopping, is largely unknown. HYPOTHESIS: When performing a single-legged forward hop landing, the reconstructed knee will demonstrate altered sagittal, frontal, and transverse plane kinematics compared with the contralateral limb. STUDY DESIGN: Controlled laboratory study. METHODS: High-speed biplane radiography was used to quantify bilateral 3-dimensional tibiofemoral joint kinematics in 9 subjects with unilaterally reconstructed anterior cruciate ligaments (mean time after surgery, 4 months) during 3 single-legged, forward hop landing trials. Mean subject-based initial foot contact and maximum stance (0-250 ms) values were calculated for each kinematic variable. Two-tailed paired t tests were subsequently applied to examine for the main effect of limb (reconstructed vs contralateral). RESULTS: The reconstructed knees exhibited significantly greater extension (P = .04), external tibial rotation (P = .006), and medial tibial translation (P = .02) than the contralateral knees at initial contact. Reconstructed knees underwent significantly greater maximum flexion (P = .05), maximum external tibial rotation (P = .01), and maximum anterior tibial translation (P = .02). No significant differences existed between limbs for initial contact (P = .65) or maximum adduction-abduction (P = .55). CONCLUSION: Tibiofemoral joint kinematics of the anterior cruciate ligament-reconstructed knee are significantly different from those of the uninjured contralateral limb during a single-legged hop landing. This altered kinematic profile, in conjunction with the large impact loads associated with hopping, may further contribute to the risk of posttraumatic knee osteoarthritis. CLINICAL RELEVANCE: Returning to sports involving dynamic single-legged landings at 4 months after anterior cruciate ligament reconstruction surgery may contribute to accelerated knee joint degeneration.

In Vivo Measurement of Glenohumeral Joint Contact Patterns.

The objectives of this study were to describe a technique for measuring in-vivo glenohumeral joint contact patterns during dynamic activities and to demonstrate application of this technique. The experimental technique calculated joint contact patterns by combining CT-based 3D bone models with joint motion data that were accurately measured from biplane x-ray images. Joint contact patterns were calculated for the repaired and contralateral shoulders of 20 patients who had undergone rotator cuff repair. Significant differences in joint contact patterns were detected due to abduction angle and shoulder condition (i.e., repaired versus contralateral). Abduction angle had a significant effect on the superior/inferior contact center position, with the average joint contact center of the repaired shoulder 12.1% higher on the glenoid than the contralateral shoulder. This technique provides clinically relevant information by calculating in-vivo joint contact patterns during dynamic conditions and overcomes many limitations associated with conventional techniques for quantifying joint mechanics.

Measuring dynamic in-vivo glenohumeral joint kinematics: technique and preliminary results.

Rotator cuff tears are a common injury that affect a significant percentage of the population over age 60. Although it is widely believed that the rotator cuff's primary function is to stabilize the humerus against the glenoid during shoulder motion, accurately measuring the three-dimensional (3D) motion of the shoulder's glenohumeral joint under in-vivo conditions has been a challenging endeavor. In particular, conventional motion measurement techniques have frequently been limited to static or two-dimensional (2D) analyses, and have suffered from limited or unknown in-vivo accuracy. We have recently developed and validated a new model-based tracking technique that is capable of accurately measuring the 3D position and orientation of the scapula and humerus from biplane X-ray images. Herein we demonstrate the in-vivo application of this technique for accurately measuring glenohumeral joint translations during shoulder motion in the repaired and contralateral shoulders of patients following rotator cuff repair. Five male subjects were tested at 3-4 months following arthroscopic rotator cuff repair. Superior-inferior humeral translation was measured during elevation, and anterior-posterior humeral translation was measured during external rotation in both the repaired and contralateral shoulders. The data failed to detect statistically significant differences between the repaired and contralateral shoulders in superior-inferior translation (p=0.74) or anterior-posterior translation (p=0.77). The measurement technique overcomes the limitations of conventional motion measurement techniques by providing accurate, 3D, in-vivo measures of glenohumeral joint motion during dynamic activities. On-going research is using this technique to assess the effects of conservative and surgical treatment of rotator cuff tears.

In vivo measurement of subacromial space width during shoulder elevation: technique and preliminary results in patients following unilateral rotator cuff repair.

BACKGROUND: The shoulder's subacromial space is of significant clinical interest due to its association with rotator cuff disease. Previous studies have estimated the subacromial space width to be 2-17 mm, but no study has measured in vivo subacromial space width during shoulder motion. The purpose of this study was to measure the in vivo subacromial space width during shoulder elevation in patients following rotator cuff repair. METHODS: Biplane X-ray images were collected during shoulder elevation of 11 patients who had undergone rotator cuff repair. Glenohumeral joint motion was measured from the biplane X-ray images for each subject's repaired and asymptomatic, contralateral shoulders. The joint motion data were combined with subject-specific CT models to measure the subacromial space width during shoulder motion. FINDINGS: Subacromial space width decreased with shoulder elevation, ranging from 2.3 to 7.4 mm in the repaired shoulder and 1.2-7.1 mm in the contralateral shoulder. Subacromial space width in the repaired shoulder was only 0.5 mm less than the contralateral shoulder when averaged over 10-60 degrees of glenohumeral elevation. INTERPRETATION: The results indicate that the humerus in the repaired shoulder is positioned more cranially on the glenoid than in the contralateral shoulder. It is unclear if these subtle differences in subacromial space width are due to the surgical procedure or post-operative stiffness, or if subacromial impingement contributed to the development of the rotator cuff tear. Future research will ascertain if these results represent a transient response to the surgery or a more fundamental difference in rotator cuff function between repaired and contralateral shoulders.

Dynamic function of the ACL-reconstructed knee during running.

Little is known about the three-dimensional behavior of the anterior cruciate ligament (ACL) reconstructed knee during dynamic, functional loading, or how dynamic knee function changes over time in the reconstructed knee. We hypothesized dynamic, in vivo function of the ACL-reconstructed knee is different from the contralateral, uninjured knee and changes over time. We measured knee kinematics for 16 subjects during downhill running 5 and 12 months after ACL reconstruction (bone-patellar tendon-bone or quadrupled hamstring tendon with interference screw fixation) using a 250 frame per second stereoradiographic system. We used repeated-measures ANOVA to ascertain whether there were differences between the uninjured and reconstructed limbs and over time. We found no differences in anterior tibial translation between limbs, but reconstructed knees were more externally rotated and in more adduction (varus) during the stance phase of running. Anterior tibial translation increased from 5 to 12 months after surgery in the reconstructed knees. Anterior cruciate ligament reconstruction failed to restore normal rotational knee kinematics during dynamic, functional loading and some degradation of graft function occurred over time. These abnormal motions may contribute to long-term joint degeneration associated with ACL injury and reconstruction.

Kinematics of the ACL-deficient canine knee during gait: serial changes over two years.

The ACL-deficient dog is a model for investigating the development and progression of mechanically driven osteoarthrosis of the knee. ACL loss creates dynamic instability in the ACL-deficient knee which presumably leads to progressive joint degeneration, but the nature of this instability over the time course of disease development is not well understood. The goal of this study was to characterize three-dimensional motion of the canine knee during gait, before and serially for two years after ACL transection. Canine tibial-femoral kinematics were assessed during treadmill gait before and serially for two years after ACL transection (ACL-D group; 18 dogs) or sham transection (ACL-I group; five dogs). Kinematic data was collected at 250 frames/s using a biplane video-radiographic system. Six degree-of-freedom motions of the tibia relative to the femur were calculated, and values immediately prior to pawstrike as well as the maximum, minimum, midpoint and range of motion during early/mid stance were extracted. Between-group differences relative to baseline (pre-transection) values, as well as changes over time post-transection, were determined with a repeated-measures ANCOVA. In the ACL-D group, peak anterior tibial translation (ATT) increased by 10 mm (p < 0.001), and did not change over time (p=0.76). Pre-pawstrike ATT was similar to ACL-intact values early on (2-4 months) but then increased significantly over time, by 3.5 mm (p < 0.001). The range of ab/adduction motion nearly doubled after ACL loss (from 3.3 degrees to 6.1 degrees). The magnitude (midpoint) of knee adduction also increased significantly over time (mean increase 3.0 degrees; p = 0.036). All changes occurred primarily between 6 and 12 months. There were no significant differences between groups in the transverse plane, and no significant changes over time in the ACL-I group. In summary, peak anterior tibial translation and coronal-plane instability increased immediately after ACL loss, and did not improve with time. ATT just prior to pawstrike and mean knee adduction throughout stance became progressively more abnormal with time, with the greatest changes occurring between 6 and 12 months after ACL transection. This may be due to overload failure of secondary restraints such as the medial meniscus, which has been reported to fail in a similar timeframe in the ACL-deficient dog. The relationships between these complex mechanical alterations and the rate of OA development/progression are currently under investigation.

Abnormal rotational knee motion during running after anterior cruciate ligament reconstruction.

BACKGROUND: The effectiveness of anterior cruciate ligament reconstruction for restoring normal knee kinematics is largely unknown, particularly during sports movements generating large, rapidly applied forces. HYPOTHESIS: Under dynamic in vivo loading, significant differences in 3-dimensional kinematics exist between anterior cruciate ligament-reconstructed knees and the contralateral, uninjured knees. STUDY DESIGN: Prospective, in vivo laboratory study. METHODS: Kinematics of anterior cruciate ligament-reconstructed and contralateral (uninjured) knees were evaluated for 6 subjects during downhill running 4 to 12 months after anterior cruciate ligament reconstruction, using a 250 frame/s stereoradiographic system. Anatomical reference axes were determined from computed tomography scans. Kinematic differences between the uninjured and reconstructed limbs were evaluated with a repeated-measures analysis of variance. RESULTS: Anterior tibial translation was similar for the reconstructed and uninjured limbs. However, reconstructed knees were more externally rotated on average by 3.8 +/- 2.3 degrees across all subjects and time points (P =.0011). Reconstructed knees were also more adducted, by an average of 2.8 +/- 1.6 degrees (P =.0091). Although differences were small, they were consistent in all subjects. CONCLUSIONS: Anterior cruciate ligament reconstruction failed to restore normal rotational knee kinematics during dynamic loading. CLINICAL RELEVANCE: Although further study is required, these abnormal motions may contribute to long-term joint degeneration associated with anterior cruciate ligament injury/reconstruction.