Kinematic, Kinetic, and Temporal Metrics Associated With Golf Proficiency

ABSTRACT

McHugh, MP, O'Mahoney, CA, Orishimo, KF, Kremenic, IJ, and Nicholas, SJ. Kinematic, kinetic, and temporal metrics associated with golf proficiency. J Strength Cond Res 38(3): 599-606, 2024-The biomechanics of the golf swing have been studied extensively, but the literature is unclear on which metrics are indicative of proficiency. The purpose of this study was to determine which metrics identified golf proficiency. It was hypothesized that discrete kinematic, kinetic, and temporal metrics would vary depending on proficiency and that combinations of metrics from each category would explain specific proficiency metrics. Kinematic, kinetic, and temporal metrics and their sequencing were collected for shots performed with a driver in 33 male golfers categorized as proficient, average, or unskilled (based on a combination of handicap, ball velocity, and driving distance). Kinematic data were collected with high-speed motion analysis, and ground reaction forces (GRF) were collected from dual force plates. Proficient golfers had greater x-factor at ball impact and greater trunk deceleration before ball impact compared with average ( p < 0.05) and unskilled ( p < 0.01) golfers. Unskilled golfers had lower x-factor at the top of the back swing and lower peak x-factor, and they took longer to reach peak trunk velocity and peak lead foot GRF compared with average ( p < 0.05) and proficient ( p < 0.05) golfers. A combination of 2 kinematic metrics (x-factor at ball impact and peak pelvis velocity), 1 kinetic metric (peak lead foot GRF), and 2 timing metrics (the timing of peak trunk and arm velocity) explained 85% of the variability in ball velocity. The finding that x-factor at ball impact and trunk deceleration identified golf proficiency points to the potential for axial trunk rotation training to improve performance.

Influence of Pain Sensitivity on Surgical Outcomes of Arthroscopic Rotator Cuff Repair: A Prospective Cohort Study

BACKGROUND

The Pain Sensitivity Questionnaire (PSQ) has been found to be a valid tool, and PSQ scores have been shown to be predictive of outcomes after surgery for lumbar stenosis. The effect of pain sensitivity on outcomes of rotator cuff repair (RCR) surgery has not been examined.

HYPOTHESIS

PSQ scores would be associated with surgical outcomes after arthroscopic RCR surgery.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

Patients 18 to 80 years old scheduled for RCR were consecutively enrolled. Patients with glenohumeral arthritis grade ≥2 or RCR revision surgery were excluded. PSQ was completed preoperatively. The Disabilities of the Arm, Shoulder and Hand score and American Shoulder and Elbow Surgeons score were used as patient-reported outcome measurements (PROMs), and visual analog scale pain score was documented as well. Active shoulder external rotation (ER), internal rotation, and anterior forward elevation range of motion (ROM) were recorded. PROMs and ROM measurements were recorded preoperatively and at 3 months, 6 months, and 1 year after surgery. Rotator cuff tear size, type of repair, and concomitant procedures were documented. Patients were classified as having high or normal pain sensitivity based on PSQ scores.

RESULTS

Of 100 enrolled patients, 38 patients were classified as having high pain sensitivity. Patients with high pain sensitivity had worse American Shoulder and Elbow Surgeons and Disabilities of the Arm, Shoulder and Hand scores preoperatively, 6 months postoperatively, and 1 year postoperatively (P < .01). From the preoperative assessment to 3 months postoperatively, PROMs improved more in patients with high versus normal pain sensitivity. However, for patients with high pain sensitivity, PROMs plateaued after 3 months but continued to improve for patients with normal pain sensitivity (P < .01). Visual analog scale pain scores were higher at all time points for patients with high pain sensitivity (P < .05). Preoperatively, patients with high pain sensitivity had restricted active ROM compared with patients who had normal pain sensitivity for anterior forward elevation, ER, and internal rotation (P = .009, P = .012, and P = .006, respectively). By 1 year after surgery, ER ROM was still restricted in patients with high pain sensitivity.

CONCLUSION

Pain sensitivity is an important factor influencing RCR outcomes. Patients with high pain sensitivity undergoing RCR showed less improvement in active ROM and worse PROMs after surgery compared with patients who had normal pain sensitivity. Preoperative PSQ may predict postoperative improvements.

Adductor Strains in Athletes

Acute adductor injuries are a common occurrence in sport. The overall incidence of adductor strains across 25 college sports was 1.29 injuries per 1000 exposures, with men's soccer (3.15) and men's hockey (2.47) having the highest incidences. As with most muscle strains there is a high rate of recurrence for adductor strains; 18% in professional soccer and 24% in professional hockey. Effective treatment, with successful return to play, and avoidance of reinjury, can be achieved with a proper understanding of the anatomy, a thorough clinical exam yielding an accurate diagnosis, and an evidence-based treatment approach, including return to play progression.

Predictive Value of MRI in Outcomes of Non-Surgical Treatment of Lateral Epicondylitis

Background

The diagnosis of lateral epicondylitis is typically made on the basis of clinical history and examination. However, magnetic resonance imaging (MRI) is often used to supplement evaluation of the patient with a painful elbow and can identify extensor carpi radialis brevis (ECRB) tendon tears. The objective of this study was to determine if ECRB tear size on MRI could be used as a prognostic indicator for patients with recalcitrant lateral epicondylitis and partial ECRB tears.

Methods

Forty-one patients with recalcitrant lateral epicondylitis and a partial ECRB tear on MRI were identified (22 men and 19 women; age: 49 ± 8 years; height: 165 ± 36 mm; weight: 73 ± 18 kg). Patients were divided into two groups based on whether they underwent surgery or not. Nonsurgical treatment was evaluated by the Disabilities of the Arm, Shoulder, and Hand questionnaire, and surgery was considered a failure of nonsurgical treatment. Nonsurgical treatment was variable and included a mixture of physical therapy, rest, injection therapy, and splinting.

Results

Of the 41 patients, 5 patients opted for immediate surgery and 36 patients were treated nonsurgically. Of those 36 patients, 11 patients had symptom relief, 19 patients had subsequent surgery, and 6 patients chose not to have surgery despite continued symptoms. Tear size on MRI did not differ significantly between the patients who had symptom relief with nonsurgical treatment and the other patients (7.7 ± 4.3 mm vs. 9.7 ± 2.5 mm, P = .07).

Discussion

Only 11 of 41 patients (27%) with recalcitrant lateral epicondylitis and ECRB tear had symptom relief with nonsurgical treatment. However, ECRB tendon defect size on MRI did not predict success or failure of nonsurgical treatment.

Resisted adduction sit-up test (RASUT) as a screening tool for pelvic versus hip pathology

Groin pain is a common symptom in hip and pelvic pathology and differentiating between the two remains a challenge. The purpose of this study was to examine whether a test combining resisted adduction with a sit-up (RASUT) differentiates between pelvic and hip pathology. The RASUT was performed on 160 patients with complaints of hip or groin pain who subsequently had their diagnosis confirmed by magnetic resonance imaging (MRI) or surgery. Patients were categorized as having pelvic pathology (athletic pubalgia or other) or hip pathology (intra-articular or other). Athletic pubalgia was defined as any condition involving the disruption of the pubic aponeurotic plate. Sensitivity, specificity, positive predictive accuracy, negative predictive accuracy and diagnostic odds ratios were computed. Seventy-one patients had pelvic pathology (40 athletic pubalgia), 81 had hip pathology and 8 had both. The RASUT was effective in differentiating pelvic from hip pathology; 50 of 77 patients with a positive RASUT had pelvic pathology versus 29 of 83 patients with a negative test (P < 0.001). RASUT was diagnostic for athletic pubalgia (diagnostic odds ratio 6.08, P < 0.001); 35 of 45 patients with athletic pubalgia had a positive RASUT (78% sensitivity) and 73 of 83 patients with a negative RASUT did not have athletic pubalgia (88% negative predictive accuracy). The RASUT can be used to differentiate pelvic from hip pathology and to identify patients without athletic pubalgia. This is a valuable screening tool in the armamentarium of the sports medicine clinician.

Electromyographic Evidence of Excessive Achilles Tendon Elongation During Isometric Contractions After Achilles Tendon Repair

Background

Weakness in end-range plantarflexion has been demonstrated after Achilles tendon repair and may be because of excessive tendon elongation. The mean frequency (MNF) of surface electromyogram (EMG) data during isometric maximum voluntary contraction (MVC) increases with muscle fiber shortening.

Hypothesis

During isometric plantarflexion, MNF during MVCs will be higher on the involved side compared with the uninvolved side after Achilles tendon repair because of excessive tendon elongation and greater muscle fiber shortening.

Study Design

Case series; Level of evidence, 4.

Methods

Isometric plantarflexion MVC torque was measured at 20° and 10° dorsiflexion, neutral, and 10° and 20° plantarflexion in 17 patients (15 men, 2 women; mean age, 39 ± 9 years) at a mean 43 ± 26 months after surgery. Surface EMG signals were recorded during strength tests. MNF was calculated from fast Fourier transforms of medial gastrocnemius (MG), lateral gastrocnemius (LG), and soleus (SOL) EMG signals.

Results

Patients had marked weakness on the involved side versus the uninvolved side in 20° plantarflexion (deficit, 28% ± 18%; P < .001) but no significant weakness in 20° dorsiflexion (deficit, 8% ± 15%; P = .195). MNF increased when moving from dorsiflexion to plantarflexion (P < .001), but overall, it was not different between the involved and uninvolved sides (P = .195). However, differences in MNF between the involved and uninvolved sides were apparent in patients with marked weakness. At 10° plantarflexion, 8 of 17 patients had marked weakness (>20% deficit). MNF at 10° plantarflexion was significantly higher on the involved side versus the uninvolved side in patients with weakness, but this was not apparent in patients with no weakness (side by group, P = .012). Mean MNF at 10° plantarflexion across the 3 muscles was 13% higher on the involved side versus the uninvolved side in patients with weakness (P = .012) versus 3% lower in patients with no weakness (P = .522).

Conclusion

Higher MNF on the involved side versus the uninvolved side in patients with significant plantarflexion weakness is consistent with greater muscle fiber shortening. This indicates that weakness was primarily because of excessive lengthening of the repaired Achilles tendon. If weakness was simply because of atrophy, a lower MNF would have been expected and patients would have had weakness throughout the range of motion. Surgical and rehabilitative strategies are needed to prevent excessive tendon elongation and weakness in end-range plantarflexion after Achilles repair.

Muscle hypotrophy, not inhibition, is responsible for quadriceps weakness during rehabilitation after anterior cruciate ligament reconstruction

PURPOSE

Quadriceps weakness is common after anterior cruciate ligament reconstruction (ACLR). Limited neuromuscular activation may have a role in the weakness. The purpose of this study was to use peripheral magnetic stimulation to measure changes in quadriceps inhibition in patients during rehabilitation from ACLR.

METHODS

Ten patients (7M/3F; age 35 ± 8 years; BMI 26.0 ± 4.8 kg/m²) who had ACLR with patellar tendon autograft were recruited. At 3 and 6 months postoperatively, patients' knee extension peak torque was measured during maximum voluntary isometric contraction (MVIC), magnetic stimulation-evoked contraction, and MVIC augmented with superimposed burst magnetic stimulation to the femoral nerve. All tests were done bilaterally at 30° and 65° of knee flexion on a dynamometer. Central activation ratio was calculated by dividing the peak torque before stimulation by peak torque after stimulation.

RESULTS

Patients had marked deficits in MVIC, with improvement from 3 to 6 months that was more apparent at 65° versus 30° (P < 0.05). There was significant deficit in stimulation-evoked torque on the involved side that diminished over time, and this change occurred differently between the two angles (P < 0.05). Central activation ratio was lower on the involved side versus the noninvolved side and this effect was more prominent at 3 versus 6 months: combining the angles, mean central activation ratio on the involved and noninvolved sides, respectively, was 91.4 ± 7.6% and 97.5 ± 5.3% at 3 months, and 93.0 ± 7.8% and 95.8 ± 6.8% at 6 months.

CONCLUSIONS

At 3 and 6 months after ACLR, there were significant deficits in quadriceps strength and activation. Quadriceps activation levels were high (> 90%) for both sides at both time points. The substantial strength deficits at this postoperative period may be largely due to muscle atrophy with limited contribution from central inhibition. Rehabilitation interventions to normalize quadriceps strength should emphasize hypertrophic stimuli as opposed to neuromuscular activation strategies.

LEVEL OF EVIDENCE

II, prospective cohort study.

Effect of Intraoperative Platelet-Rich Plasma Treatment on Postoperative Donor Site Knee Pain in Patellar Tendon Autograft Anterior Cruciate Ligament Reconstruction: A Double-Blind Randomized Controlled Trial

BACKGROUND

Donor site morbidity in the form of anterior knee pain is a frequent complication after bone-patellar tendon-bone (BPTB) autograft anterior cruciate ligament (ACL) reconstruction. Hypothesis/Purpose: The purpose was to examine the effect of the intraoperative administration of platelet-rich plasma (PRP) on postoperative kneeling pain. It was hypothesized that PRP treatment would reduce knee pain.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 2.

METHODS

Fifty patients (mean ± SD age, 30 ± 12 years) undergoing BPTB ACL autograft reconstruction were randomized to the PRP (n = 27) or sham (n = 23) treatment. In either case, 10 mL of venous blood was drawn before the induction of anesthesia and either discarded (sham) or processed (PRP) for preparation of a PRP gel to be later mixed with donor site bone chips and inserted into the patellar defect. At 12 weeks, 6 months, 1 year, and 2 years after surgery, patients completed International Knee Documentation Committee (IKDC) forms and visual analog scale pain scores for activities of daily living and kneeling. Healing indices at the donor site were assessed by routine noncontrast magnetic resonance imaging (MRI) at 6 months. Mixed-model analysis of variance was used to assess the effect of PRP on patient symptoms and MRI indices of donor site healing, as measured by the width of the donor site defect.

RESULTS

Kneeling pain, pain with activities of daily living, and IKDC scores were not different between treatment groups at any of the time intervals ( P = .08-.83). Kneeling pain improved from 12 weeks to 6 months and from 1 to 2 years ( P < .05). IKDC scores improved substantially from 12 weeks to 6 months ( P < .001) and continued to improve to 2 years (PRP, 86 ± 19; sham, 89 ± 10). MRI indices of donor site healing were not different between treatment groups ( P = .53-.90).

CONCLUSION

Whether randomized to receive PRP in their patellar defect or not, patients continued to have similar levels of kneeling pain and patellar defect sizes after autograft BPTB ACL reconstruction. Registration: NCT01765712 ( ClinicalTrials.gov identifier).

Can Weakness in End-Range Plantar Flexion After Achilles Tendon Repair Be Prevented?

Background

Disproportionate end-range plantar flexion weakness, decreased passive stiffness, and inability to perform a heel rise on a decline after Achilles tendon repair are thought to reflect increased tendon compliance or tendon lengthening. Since this was first noted, we have performed stronger repairs and avoided stretching into dorsiflexion for the first 12 weeks after surgery.

Hypothesis

Using stronger repairs and avoiding stretching into dorsiflexion would eliminate end-range plantar flexion weakness and normalize passive stiffness.

Study Design

Case series; Level of evidence, 4.

Methods

Achilles repairs with epitendinous augmentation were performed on 18 patients. Plantar flexion torque, dorsiflexion range of motion (ROM), passive joint stiffness, and standing single-legged heel rise on a decline were assessed at 43 ± 24 months after surgery (range, 9 months to 8 years). Maximum isometric plantar flexion torque was measured at 20° and 10° of dorsiflexion, neutral position, and 10° and 20° of plantar flexion. Passive dorsiflexion ROM was measured with a goniometer. Passive joint stiffness was computed from the increase in passive torque from 10° to 20° of dorsiflexion. Tendon thickness was measured by use of digital calipers. Plantar flexion electromyographic (EMG) data were recorded during strength and functional tests. Analysis of variance and chi-square tests were used to assess weakness and function.

Results

Marked weakness was evident on the involved side at 20° of plantar flexion (deficit, 26% ± 18%; P < .001), with no weakness at 20° of dorsiflexion (deficit, 6% ± 17%; P = .390). Dorsiflexion ROM was decreased 5.5° ± 8° (P = .015), and tendon width was 8 ± 3 mm greater on the involved side (P < .001). Passive joint stiffness was similar between the involved and noninvolved sides. Only 2 of 18 patients could perform a decline heel rise on the involved side compared with 18 of 18 on the noninvolved side (P = .01). No difference in EMG amplitude was found between the involved and noninvolved sides during the strength or heel rise tests.

Conclusion

The use of stronger repair techniques and attempts to limit tendon elongation by avoiding dorsiflexion stretching did not eliminate weakness in end-range plantar flexion. EMG data confirmed that end-range weakness was not due to neural inhibition. Physiological changes that alter the force transmission capability of the healing tendon may be responsible for this continued impairment. This weakness has implications for high-demand jumping and sprinting after Achilles tendon repair.

The Effect of Postoperative KT-1000 Arthrometer Score on Long-Term Outcome After Anterior Cruciate Ligament Reconstruction

BACKGROUND

Many long-term studies have looked at outcomes after anterior cruciate ligament reconstruction (ACLR), but none have correlated long-term outcomes with postoperative laxity greater than 5 mm. It has been stated previously that more than 5 mm of postoperative graft laxity constituted a procedural failure.

PURPOSE

To directly compare tight grafts (<3 mm) and loose grafts (>5 mm) to determine the effect of graft laxity, as measured by KT-1000 arthrometer, after ACLR on long-term clinical outcomes.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

The study included 171 consecutive patients who had undergone transtibial bone-patellar tendon-bone ACLR between 1992 and 1998. At 6, 12, and 24 months postoperatively (the immediate postoperative period), patients were evaluated. Group A included patients with a maximal side-to-side (STS) difference in the immediate postoperative period of less than 3 mm (tight grafts), and group B included patients with a maximal STS difference of greater than 5 mm (loose grafts). Any patient with a history of ipsilateral or contralateral ACLR or ACL injury, meniscectomy, or cartilage restoration was excluded. Patients were prospectively followed to long-term follow-up, when a telephone interview was conducted regarding knee function and to document Lysholm, Tegner, Knee injury and Osteoarthritis Outcome Score (KOOS), and International Knee Documentation Committee (IKDC) subjective outcome scores.

RESULTS

Eighty-seven patients met inclusion criteria: 66 tight grafts (group A) and 21 loose grafts (group B). The mean ± SD time to follow-up was 16.3 ± 1.5 years in group A (n = 46) and 16.8 ± 1.3 years in group B (n = 15). Tegner ( P = .77), Lysholm ( P = .85), KOOS ( P = .96), and IKDC ( P = .42) were found to have no statistically significant difference between groups at long-term follow-up. Both Tegner and Lysholm scores significantly improved in tight and loose grafts in the immediate postoperative period as well as at long-term follow-up compared with preoperatively. There were 2 ACL revisions in group A and none in group B. Eleven of 46 patients (24%) in group A required subsequent procedures versus 1 of 15 patients (6.7%) in group B ( P = .146).

CONCLUSION

Postoperative laxity of greater than 5 mm STS difference as measured by KT-1000 arthrometer does not appear to place patients at a worse clinical outcome at long-term follow-up, nor does it lead to significantly more subsequent procedures. In addition, transtibial ACLR can provide excellent clinical results at long-term follow-up.

Functional Outcomes After Double-Row Versus Single-Row Rotator Cuff Repair: A Prospective Randomized Trial

Background:

The functional benefits of double-row (DR) versus single-row (SR) rotator cuff repair are not clearly established.

Purpose:

To examine the effect of DR versus SR rotator cuff repair on functional outcomes and strength recovery in patients with full-thickness tears.

Study Design:

Randomized controlled trial; Level of evidence, 2.

Methods:

Forty-nine patients were randomized to DR or SR repairs; 36 patients (13 women, 23 men; mean age, 62 ± 7 years; 20 SR, 16 DR) were assessed at a mean 2.2 ± 1.6 years after surgery (range, 1-7 years; tear size: 17 medium, 13 large, 9 massive). The following data were recorded prior to surgery and at follow-up: Penn shoulder score, American Shoulder and Elbow Surgeons (ASES), and Simple Shoulder Test (SST) results; range of motion (ROM) for shoulder flexion, external rotation (ER) at 0° and 90° of abduction, and internal rotation (IR) at 90° of abduction; and shoulder strength (Lafayette manual muscle tester) in empty- and full-can tests, abduction, and ER at 0° of abduction. Treatment (SR vs DR) × time (pre- vs postoperative) mixed-model analysis of variance was used to assess the effect of rotator cuff repair.

Results:

Rotator cuff repair markedly improved Penn, ASES, and SST scores (P < .001), with similar improvement between SR and DR repairs (treatment × time, P = .38-.10) and excellent scores at follow-up (DR vs SR: Penn, 91 ± 11 vs 92 ± 11 [P = .73]; ASES, 87 ± 12 vs 92 ± 12 [P = .21]; SST, 11.4 ± 1.0 vs 11.3 ± 1.0 [P = .76]). Patients with DR repairs lost ER ROM at 0° of abduction (preoperative to final follow-up, 7° ± 10° loss [P = .013]). ER ROM did not significantly change with SR repair (5° ± 14° gain, P = .16; treatment by time, P = .008). This effect was not apparent for ER ROM at 90° of abduction (treatment × time, P = .26). IR ROM improved from preoperative to final follow-up (P < .01; SR, 17° ± 27°; DR, 7° ± 21°; treatment × time, P = .23). Rotator cuff repair markedly improved strength in empty-can (54%), full-can (66%), abduction (47%), and ER (54%) strength (all P < .001), with no difference between SR and DR repairs (P = .23-.75). All clinical tests with the exception of the lift-off test were normalized at follow-up (P < .05).

Conclusion:

Outcomes were not different between SR or DR repair, with generally excellent outcomes for both groups. Rotator cuff repair and subsequent rehabilitation markedly improved shoulder strength.

The Effect of a High Pitch Volume on Musculoskeletal Adaptations in High School Baseball Pitchers

BACKGROUND

Shoulder range of motion and strength adaptations occur at an early age in baseball pitchers.

PURPOSE/HYPOTHESIS

The purpose of this study was to examine the effect of pitch volume on in-season and year-to-year range of motion (ROM) and strength adaptations in high school baseball pitchers. The hypothesis was that a high pitch volume will not affect range of motion asymmetries but will impair supraspinatus strength.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

Pre- and postseason ROM and strength measures were performed on pitchers from 3 high schools for 4 consecutive seasons, for a total of 95 player-seasons (mean ± SD participant age, 16 ± 1 years). Preseason measures were repeated the next year on players returning to the teams, for a total of 71 consecutive player-seasons. ROM tests included internal-external rotation and posterior shoulder flexibility. Strength tests (hand-held dynamometer) included internal-external rotation, supraspinatus, and scapular retraction. Pitchers were categorized by pitch count for the season (high, >400; moderate, 180-400; low, <180). ROM and strength changes in the dominant versus nondominant arm were assessed by analysis of variance.

RESULTS

Dominant versus nondominant ROM differences did not change from pre- to postseason (P = .36-.99) or from one year to the next (P = .46-.86), with no effect of pitch volume (P = .23-.87). Supraspinatus strength decreased in the dominant arm during the season, with 13% loss in high-volume pitchers (P < .001) and insignificant losses in moderate- (6%) and low-volume pitchers (2%). Strength in other tests was unaffected by pitch volume. Consistent with physical development, strength increased bilaterally from one year to the next (supraspinatus, 12%; external rotation, 15%; internal rotation, 14%; scapular retraction, 23%; P < .001). Supraspinatus strength gain in the dominant arm was affected by prior pitch volume (P = .02): 24% in low-volume pitchers (P < .01), with no significant change in moderate-volume (0%; P = .99) or high-volume (5%; P = .99) pitchers.

CONCLUSION

Dominant versus nondominant ROM differences did not progress during the season, or from one year to the next, and were unaffected by pitch volume. A high pitch volume was associated with in-season supraspinatus weakness and diminished strength gains from one year to the next. In conclusion, a high pitch volume appeared to have a catabolic effect on supraspinatus strength.

Differential Effect of Total Knee Arthroplasty on Valgus and Varus Knee Biomechanics During Gait

BACKGROUND

Total knee arthroplasty and its relation to gait abduction or adduction moment has not been fully described.

METHODS

Gait analysis was performed on 25 patients (27 knees) preoperatively, 6 months and 1 year after total knee arthroplasty. Reflective markers were placed on the lower extremity, and motion data were collected at 60 Hz using 6 infrared cameras. Ground reaction forces were recorded at 960 Hz with a force plate. Stance phase was divided into braking and propulsive phases. Coronal knee angles and moments were calculated. Repeated-measures analysis of variance was used to compare frontal plane knee impulse over time and between the braking and propulsive phases of stance.

RESULTS

In varus knees, static alignment was corrected from 2.2° varus to 3.3° valgus and in valgus knees from 15.2° valgus to 2.7° valgus (P < .010). Braking phase adduction impulse decreased from 0.145 to 0.111 at 6 months but increased to 0.126 Nm/kg s (P > .05) at 1 year. Propulsive phase impulse changed from 0.129 to 0.085 and persisted at 1 year. Impulse changed from 0.01 (abduction) to 0.11 Nm/kg s (adduction) at 6 months and persisted (P = .01).

CONCLUSION

Restoration of anatomic alignment and soft tissue balancing changes the lateral loading conditions of valgus knees. Both cases, between 6 months and 1 year, increased peak moment.

Performance Demands in Softball Pitching: A Comprehensive Muscle Fatigue Study

BACKGROUND

Monitoring pitch count is standard practice in minor league baseball but not in softball because of the perception that fast-pitch softball pitching is a less stressful motion.

PURPOSE

To examine muscle fatigue after fast-pitch softball performances to provide an assessment of performance demand.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Bilateral strength measurements (handheld dynamometer) were made on 19 female softball pitchers (mean age [±SD], 15.2 ± 1.2 years) before and after pitching a game (mean number of pitches, 99 ± 21; mean innings pitched, 5 ± 1). A total of 20 tests were performed on the dominant and nondominant sides: forearm (grip, wrist flexion/extension, pronation/supination, elbow flexion/extension), shoulder (flexion, abduction/adduction, external/internal rotation, empty can test), scapula (middle/lower trapezius, rhomboid), and hip (hip flexion/extension, abduction/adduction). Fatigue (percentage strength loss) was categorized based on bilateral versus unilateral presentation using paired t tests: bilateral symmetric (significant on dominant and nondominant and not different between sides), bilateral asymmetric (significant on dominant and nondominant but significantly greater on dominant), unilateral asymmetric (significant on dominant only and significantly greater than nondominant), or unilateral equivocal (significant on dominant only but not different from nondominant).

RESULTS

Bilateral symmetric fatigue was evident for all hip (dominant, 19.3%; nondominant, 15.2%) and scapular tests (dominant, 19.2%; nondominant, 19.3%). In general, shoulder tests exhibited bilateral asymmetric fatigue (dominant, 16.9%; nondominant, 11.6%). Forearm tests were more variable, with bilateral symmetric fatigue in the elbow flexors (dominant, 22.5%; nondominant, 19.2%), and wrist flexors (dominant, 21.6%; nondominant, 19.0%), bilateral asymmetric fatigue in the supinators (dominant, 21.8%; nondominant, 15.5%), unilateral asymmetric fatigue in the elbow extensors (dominant, 22.1%; nondominant, 11.3%), and unilateral equivocal fatigue in the pronators (dominant, 18.8%; nondominant, 15.2%) and grip (dominant, 11.4%; nondominant, 6.6%). The mean (±SD) pitch velocity was 49 ± 4 mph, with a small loss of velocity from the first to last inning pitched (3.4% ± 5.0%, P < .01).

CONCLUSION

Fast-pitch softball pitching resulted in profound bilateral fatigue in the hip and scapular muscles, with more selective fatigue in the shoulder and arm muscles.

CLINICAL RELEVANCE

These findings emphasize the importance of strength in the proximal musculature to provide a stable platform for the arm to propel the ball.

Restoring Isometry in Lateral Ulnar Collateral Ligament Reconstruction

PURPOSE

To ascertain whether placing the humeral attachment of the lateral ulnar collateral ligament (LUCL) at the humeral center of rotation (hCOR) on the humerus would provide the most isometric reconstruction.

METHODS

We analyzed 13 cadaver limbs from mid-humerus to the hand. The morphology of the ligament complex was assessed. The hCOR was then found using radiographic parameters. We chose 7 points on the humerus located at and around the hCOR and 3 points paralleling the supinator crest of the ulna and then calculated distances from these points using a digital caliper at 0°, 30°, 60°, 90°, and 130° flexion. Differences in potential ligamentous lengths (termed graft elongation) were then calculated and statistical analysis was performed.

RESULTS

There was no perfectly isometric point along the humerus or ulna. However, in all specimens the hCOR was the most isometric point for the humeral reconstruction site, with an average graft elongation of 1.1 mm. Differences in humeral tunnel position dramatically affected graft elongation at all 3 ulnar insertions. Overall, ulnar position had a minimal effect on graft elongation.

CONCLUSIONS

Although no perfectly isometric points were found, the humeral center of rotation consistently reproduced the most isometry when assessing graft elongation over range of motion. These data may assist surgeons in proper tunnel placement in LUCL reconstruction.

CLINICAL RELEVANCE

In LUCL reconstruction, the humeral tunnel should be placed as close as possible to the center of rotation, whereas placement on the ulna is less critical.

Kinematic analysis of the indirect femoral insertion of the anterior cruciate ligament: implications for anatomic femoral tunnel placement

PURPOSE

To determine the effect of debriding the indirect insertion component of the femoral anterior cruciate ligament (ACL) attachment on tibiofemoral kinematics when compared with the intact knee.

METHODS

Knee kinematics were measured in 9 cadaveric knees with the ACL intact, after indirect insertion debridement, and after ACL transection. Three loading conditions were used: (1) a 134-N anterior tibial load, (2) a combined 10-Nm valgus and 5-Nm internal tibial torque, and (3) a simulated robotic pivot shift. Anterior tibial translation (ATT) was recorded in response to anterior and combined loads at 0°, 15°, 30°, 45°, 60°, and 90° of flexion. Posterior tibial translation and external tibial rotation were recorded during the simulated pivot shift.

RESULTS

With an anterior load, indirect insertion debridement increased ATT by 0.37 ± 0.24 mm at 0° (P = .002) and by 0.16 ± 0.19 mm at 15° (P = .033; increases <1 mm in all specimens). ACL transection increased ATT in response to an anterior load (P = .0001) with maximum effect at 15° compared with the intact and debrided states (11.26 ± 1.15 mm and 11.04 ± 1.08 mm, respectively). With a combined load, indirect insertion debridement increased ATT by 0.17 ± 0.11 mm at 0° (P = .001; increases <0.3 mm in all specimens) with no effect at other angles. ACL transection increased ATT in response to a combined load (P = .001) with maximum effect at 15° (4.45 ± 0.85 mm v ACL intact and 4.44 ± 0.84 mm v debrided indirect insertion). In the ACL intact condition, the pivot shift produced 1.29 ± 1.34 mm of posterior tibial translation and 1.54 ± 1.61° of external tibial rotation, as compared with 1.28 ± 1.34 mm and 1.54 ± 1.47°, respectively, after debridement (P = .68 and P = .99, respectively) and 12.79 ± 3.22 mm and 17.60 ± 4.30°, respectively, after ACL transection (P = .0001).

CONCLUSIONS

The indirect femoral ACL insertion contributes minimally to restraint of tibial translation and rotation.

CLINICAL RELEVANCE

Femoral tunnel positioning for anatomic ACL reconstruction should aim to recreate the biomechanically significant direct insertion.

Risk Factors for Shoulder and Elbow Injuries in High School Baseball Pitchers: The Role of Preseason Strength and Range of Motion

BACKGROUND

Shoulder strength and motion deficits in high school baseball pitchers have been implicated in injury risk.

PURPOSE/HYPOTHESIS

To prospectively determine if preseason strength and range of motion (ROM) are predictive of injury in high school baseball pitchers. It was hypothesized that ROM asymmetries and weakness would be predictive of injury.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

Preseason strength and ROM measurements were made on 101 pitchers from 4 different high schools over 4 seasons (total 166 pitcher-seasons: 25 freshman, 46 junior varsity, and 95 varsity player-seasons). Glenohumeral internal rotation (IR), glenohumeral external rotation, and posterior shoulder ROM were measured bilaterally. Strength in IR, external rotation, supraspinatus (empty-can test), and scapular retraction was measured bilaterally (handheld dynamometer). Injury incidence (injuries per 1000 pitches) was computed for players categorized as above normal (≥1 SD above the mean), normal (within 1 standard deviation of the mean), and below normal (≤1 SD below the mean) for each potential risk factor. Injury was defined as a missed game or practice because of shoulder or elbow problem.

RESULTS

There were 28 upper extremity injuries (19 shoulder, 9 elbow; incidence, 0.58 injuries/1000 pitches). There was a trend for supraspinatus weakness to be associated with increased injury risk (relative risk [RR], 3.60; 95% CI, 0.75-17.32; P = .09). When analyzing major injuries only (>3 missed games), preseason supraspinatus weakness was significantly associated with increased injury risk (RR, 4.58; 95% CI, 1.40-15.01; P = .02). Paradoxically, pitchers with no IR loss were at increased risk compared with pitchers with ≥20° loss (RR, 4.85; 95% CI, 1.01-23.29; P = .04). Other ROM and strength measures were unrelated to injury risk.

CONCLUSION

Although excessive loss of IR ROM is thought to be a risk factor for injury, the opposite was the case in this study. The absence of IR ROM loss in high school pitchers may indicate inadequate prior exposure to pitching, resulting in increased injury risk. Preseason supraspinatus weakness was associated with increased risk for a major injury, and preventative supraspinatus strengthening may be beneficial.

Clinical outcomes of the addition of eccentrics for rehabilitation of previously failed treatments of golfers elbow

INTRODUCTION AND PURPOSE

Eccentric training of the wrist extensors has been shown to be effective in treating chronic lateral epicondylosis. However, its efficacy in the treatment of medial epicondylosis has yet to be demonstrated. The objective of this study was to assess the effectiveness of a novel eccentric wrist flexor exercise added to standard treatment for chronic medial epicondylosis in patients who did not respond to previous therapeutic interventions for this disorder.

NUMBER OF SUBJECTS

20.

MATERIALS/METHODS

Patients (13 men, 7 women; age 49±12 yr) with chronic medial epicondylosis who had failed previous treatment for this disorder (physical therapy 7, cortisone injection 7, PRP 1, NSAIDS 15) were prescribed isolated eccentrics in addition to wrist stretching, ultrasound, cross-friction massage, heat and ice. The specific isolated eccentric wrist flexor strengthening exercise performed by the patients involved twisting a rubber bar (Flexbar, Hygenic Corportation, Akron OH) with concentric wrist flexion of the noninvolved arm and releasing the twist by eccentrically contracting the wrist flexors of the involved arm (3 × 15 twice daily). A DASH questionnaire was recorded at baseline and again after the treatment period. Treating clinicians were blinded to baseline DASH scores. Treatment effect was assessed using paired t-test. Based on previous work it was estimated that with a sample of 20 patients there would be 80% power to detect a 13 point improvement in DASH scores (p<.05).

RESULTS

The pathology was in the dominant arm of 18 patients and recurrent in 10. Primary symptomatic activities were golf (14), tennis (2), basketball (1), weight lifting (1), and general activities of daily living (2). There was a significant improvement in outcomes following the addition of isolated eccentrics (Pre DASH 34.7±16.2 vs. Post DASH 7.9±11.1, p<.001). For the 18 patients involved in sports, the sports module of the DASH score improved from 73.9±28.9 to 13.2±25.0, p<.001). Physical therapy visits ranged from 1-22 with an average of 12±6 and, average treatment duration of 6.1±2.5 wks (range 1-10). Home exercise program compliance was recorded for each subject (15 full, 3 mostly, 1 occasionally, 1 none).

CONCLUSIONS

The outcome measure for chronic medial epicondylosis was markedly improved with the addition of an eccentric wrist flexor exercise to standard physical therapy. Given the inconsistent outcomes for patients previously treated with chronic medial epicondylosis the addition of isolated eccentrics seems warranted based on the results of this study.

CLINICAL RELEVANCE

This novel exercise, using an inexpensive rubber bar, provides a practical means of adding isolated eccentric training to the treatment of chronic medial epicondylosis.

LEVEL OF EVIDENCE

2b.

Is valgus unloader bracing effective in normally aligned individuals: implications for post-surgical protocols following cartilage restoration procedures

PURPOSE

Utilizing valgus unloader braces to reduce medial compartment loading in patients undergoing cartilage restoration procedures may be an alternative to non-weightbearing post-operative protocols in these patients. It was hypothesized that valgus unloader braces will reduce knee adduction moment during the stance phase in healthy subjects with normal knee alignment.

METHODS

Gait analysis was performed on twelve adult subjects with normal knee alignment and no history of knee pathology. Subjects were fitted with an off-the-shelf adjustable valgus unloader brace and tested under five conditions: one with no brace and four with increasing valgus force applied by the brace. Frontal and sagittal plane knee angles and external moments were calculated during stance via inverse dynamics. Analyses of variance were used to assess the effect of the brace conditions on frontal and sagittal plane joint angles and moments.

RESULTS

With increasing tension in the brace, peak frontal plane knee angle during stance shifted from 1.6° ± 4.2° varus without the brace to 4.1° ± 3.6° valgus with maximum brace tension (P = 0.02 compared with the no brace condition). Peak knee adduction moment and knee adduction impulse decreased with increasing brace tension (main effect of brace, P < 0.001). Gait velocity and sagittal plane knee biomechanics were minimally affected.

CONCLUSION

The use of these braces following a cartilage restoration procedure may provide adequate protection of the repair site without limiting the patient's mobility.

By what mechanism does ondansetron inhibit colonic migrating motor complexes: does it require endogenous serotonin in the gut wall?

BACKGROUND

5-HT3 antagonists, such as ondansetron (Zofran), retard colonic transit and provide effective relief of symptoms of chronic diarrhea and diarrhea-predominant irritable bowel syndrome (IBS), but the mechanism by which ondansetron retards transit is unclear. What is clear is that the frequency of colonic migrating motor complexes (CMMCs) is reduced by ondansetron, which could account for reduced transit. Our aim was to determine whether an acute depletion of 5-HT from enteric neurons would inhibit spontaneous CMMCs; and determine whether the sensitivity of ondansetron to reduce CMMC frequency would change in a 5-HT-depleted preparation.

METHODS

Mice were injected with reserpine, 24 h prior to euthanasia to deplete neuronally synthesized 5-HT. Mechanical recordings were made from proximal and mid-distal regions of isolated whole mouse colon. Immunohistochemical staining for 5-HT was used to detect neuronal 5-HT.

KEY RESULTS

Reserpine depleted all detectable 5-HT from enteric nerves. In whole colons, with mucosa and submucosal plexus removed, the frequency and amplitude of spontaneous CMMCs was not different between groups treated with or without reserpine. Surprisingly, in mucosa and submucosal plexus-free preparations, ondansetron was equally or significantly more effective at inhibiting CMMC frequency compared with control preparations (containing 5-HT). Reserpine pretreatment had no effect on the sensitivity of ondansetron to inhibit CMMCs.

CONCLUSIONS & INFERENCES

Endogenous 5-HT in enteric neurons (or the mucosa) is not required for the spontaneous generation or propagation of CMMCs. Furthermore, the primary mechanism by which ondansetron inhibits CMMC frequency is not mediated via the mucosa, submucosal plexus or 5-HT in myenteric neurons.

Is serotonin in enteric nerves required for distension-evoked peristalsis and propulsion of content in guinea-pig distal colon?

Recent studies have shown genetic deletion of the gene that synthesizes 5-HT in enteric neurons (tryptophan hydroxylase-2, Tph-2) leads to a reduction in intestinal transit. However, deletion of the Tph-2 gene also leads to major developmental changes in enteric ganglia, which could also explain changes in intestinal transit. We sought to investigate this further by acutely depleting serotonin from enteric neurons over a 24-h period, without the confounding influences induced by genetic manipulation. Guinea-pigs were injected with reserpine 24h prior to euthanasia. Video-imaging and spatio-temporal mapping was used to record peristalsis evoked by natural fecal pellets, or slow infusion of intraluminal fluid. Immunohistochemical staining for 5-HT was used to detect the presence of serotonin in the myenteric plexus. It was found that endogenous 5-HT was always detected in myenteric ganglia of control animals, but never in guinea-pigs treated with reserpine. Interestingly, peristalsis was still reliably evoked by either intraluminal fluid, or fecal pellets in reserpine-treated animals that also had their entire mucosa and submucosal plexus removed. In these 5-HT depleted animals, there was no change in the frequency of peristalsis or force generated during peristalsis. In control animals, or reserpine treated animals, high concentrations (up to 10 μM) of ondansetron and SDZ-205-557, or granisetron and SDZ-205-557 had no effect on peristalsis. In summary, acute depletion of serotonin from enteric nerves does not prevent distension-evoked peristalsis, nor propulsion of luminal content. Also, we found no evidence that 5-HT3 and 5-HT4 receptor activation is required for peristalsis, or propulsion of contents to occur. Taken together, we suggest that the intrinsic mechanisms that generate peristalsis and entrain propagation along the isolated guinea-pig distal colon are independent of 5-HT in enteric neurons or the mucosa, and do not require the activation of 5-HT3 or 5-HT4 receptors.

Groin injuries in sports medicine

Context:

An in-season groin injury may be debilitating for the athlete. Proper diagnosis and identification of the pathology are paramount in providing appropriate intervention. Furthermore, an adductor strain that is treated improperly can become chronic and career threatening. Any one of the 6 muscles of the adductor muscle group can be involved. The degree of injury can range from a minor strain (grade 1), where minimal playing time is lost, to a severe strain (grade 3), in which there is complete loss of muscle function. Persistent groin pain and muscle imbalance may lead to athletic pubalgia.

Evidence Acquisition:

Relevant studies were identified through a literature search of MEDLINE and the Cochrane database from 1990 to 2009, as well as a manual review of reference lists of identified sources.

Results:

Ice hockey and soccer players seem particularly susceptible to adductor muscle strains. In professional ice hockey and soccer players throughout the world, approximately 10% to 11% of all injuries are groin strains. These injuries have been linked to hip muscle weakness, a previous injury to that area, preseason practice sessions, and level of experience. This injury may be prevented if these risk factors are addressed before each season.

Conclusion:

Despite the identification of risk factors and strengthening intervention for athletes, adductor strains continue to occur throughout sport. If groin pain persists, the possibility of athletic pubalgia needs to be explored, because of weakening or tears in the abdominal wall muscles. A diagnosis is confirmed by exclusion of other pathology.

Does total knee arthroplasty change frontal plane knee biomechanics during gait?

BACKGROUND

Dynamic knee varus angle and adduction moments have been reported to be reduced after TKA. However, it is unclear whether this reduction is maintained long term.

QUESTIONS/PURPOSES

We therefore asked whether (1) the dynamic knee adduction angle and moment remain reduced 1 year after TKA, (2) if changes in adduction moment are related to static alignment and varus angle during gait 6 months and 1 year after TKA, and (3) if these changes in loading pattern are related to changes in Knee Society scores.

METHODS

We performed gait analysis on 15 patients (17 TKAs) before surgery and 6 months and 1 year after TKA. Weightbearing radiographs were used to assess coronal plane knee alignment.

RESULTS

TKA corrected static knee alignment from 2.2° (2.5°) varus to 3.5° (2.7°) valgus at 6 months. Peak varus angle during gait was reduced from 9.7° (6.5°) to 3.6° (5.8°) at 6 months and 5.2° (7.6°) at 1 year. Peak adduction moment was reduced to 85% of the preoperative level at 6 months but increased to 94% of the preoperative level at 1 year. We observed a correlation between the increase in dynamic varus angle and increase in adduction moment from the 6-month to 1-year followups.

CONCLUSIONS

TKA improves knee adduction moment at 6 months, but this effect is lost with time (1 year).

CLINICAL RELEVANCE

Despite restoration of static knee alignment, knee adduction moment remains high presumably predisposing to medial polyethylene wear as noted by retrieval studies.

Adaptations in single-leg hop biomechanics following anterior cruciate ligament reconstruction

When a patient performs a clinically normal hop test based on distance, it cannot be assumed that the biomechanics are similar between limbs. The objective was to compare takeoff and landing biomechanics between legs in patients who have undergone anterior cruciate ligament reconstruction. Kinematics and ground reaction forces were recorded as 13 patients performed the single-leg hop on each leg. Distance hopped, joint range of motion, peak joint kinetics and the peak total extensor moment were compared between legs during both takeoff and landing. Average hop distance ratio (involved/noninvolved) was 93 ± 4%. Compared to the noninvolved side, knee motion during takeoff on the involved side was significantly reduced (P = 0.008). Peak moments and powers on the involved side were lower at the knee and higher at the ankle and hip compared with the noninvolved side (Side by Joint P = 0.011; P = 0.003, respectively). The peak total extensor moment was not different between legs (P = 0.305) despite a decrease in knee moment and increases in ankle and hip moments (Side by Joint P = 0.015). During landing, knee motion was reduced (P = 0.043), and peak power absorbed was decreased at the knee and hip and increased at the ankle on the involved side compared to the noninvolved side (P = 0.003). The compensations by other joints may indicate protective adaptations to avoid overloading the reconstructed knee.

The effect of distal clavicle excision on in situ graft forces in coracoclavicular ligament reconstruction

BACKGROUND

Recently, some have suggested that the acromioclavicular articulation confers stability to the construct after coracoclavicular ligament reconstruction for acromioclavicular joint separation. Therefore, it has been suggested that distal clavicle excision should not be performed in this context to protect the graft during healing.

HYPOTHESIS

Sectioning the acromioclavicular ligaments would significantly increase in situ forces of a coracoclavicular ligament graft, whereas performing a distal clavicle resection would not further increase in situ graft forces.

DESIGN

Controlled laboratory study.

METHODS

A simulated coracoclavicular reconstruction was performed on 5 cadaveric shoulders. Static loads of 80 N and 210 N were applied directly to the clavicle in 5 directions: anterior, anterosuperior, superior, posterosuperior, and posterior. The in situ graft force was measured using a force transducer under 3 testing conditions: (1) intact acromioclavicular ligaments, (2) sectioned acromioclavicular ligaments, and (3) distal clavicle excision.

RESULTS

For both magnitudes of load, in all directions, in situ graft force with intact acromioclavicular ligaments was significantly less than that with sectioned acromioclavicular ligaments (P < .001). Distal clavicle excision did not further increase the in situ graft forces with load applied to the clavicle in an anterior, anterosuperior, or superior direction. However, in situ graft forces were increased with distal clavicle excision when the clavicle was loaded with 210 N in the posterosuperior direction (60.4 ± 6.3 N vs 52.5 ± 7.1 N; P = .048) and tended to be increased with posterior loading of the clavicle (71.8 ± 6.2 N vs 53.1 ± 8.8 N; P = .125).

CONCLUSION

Intact acromioclavicular ligaments protect the coracoclavicular reconstruction by decreasing the in situ graft force. The slight increase in the in situ graft force only in the posterosuperior and posterior direction after distal clavicle excision suggests only a marginal protective role of the acromioclavicular articulation. Further, the peak graft forces observed represent only a small fraction of the ultimate failure strength of the graft.

CLINICAL RELEVANCE

Distal clavicle excision can perhaps be safely performed in the context of coracoclavicular ligament reconstruction without subjecting the graft to detrimental in situ force. Although the acromioclavicular articulation serves only a marginal role in protecting the coracoclavicular ligament graft, reconstruction of the acromioclavicular ligaments may serve an important role in decreasing in situ graft force during healing.

Addition of isolated wrist extensor eccentric exercise to standard treatment for chronic lateral epicondylosis: a prospective randomized trial

BACKGROUND

Isokinetic eccentric training of the wrist extensors has recently been shown to be effective in treating chronic lateral epicondylosis. However, isokinetic dynamometry is not widely available or practical for daily exercise prescription. Therefore, the objective of this study was to assess the efficacy of a novel eccentric wrist extensor exercise added to standard treatment for chronic lateral epicondylosis.

MATERIALS AND METHODS

Twenty-one patients with chronic unilateral lateral epicondylosis were randomized into an eccentric training group (n = 11, 6 men, 5 women; age 47 +/- 2 yr) and a Standard Treatment Group (n = 10, 4 men, 6 women; age 51 +/- 4 yr). DASH questionnaire, VAS, tenderness measurement, and wrist and middle finger extension were recorded at baseline and after the treatment period.

RESULTS

Groups did not differ in terms of duration of symptoms (Eccentric 6 +/- 2 mo vs Standard 8 +/- 3 mos., P = .7), number of physical therapy visits (9 +/- 2 vs 10 +/- 2, P = .81) or duration of treatment (7.2 +/- 0.8 wk vs 7.0 +/- 0.6 wk, P = .69). Improvements in all dependent variables were greater for the Eccentric Group versus the Standard Treatment Group (percent improvement reported): DASH 76% vs 13%, P = .01; VAS 81% vs 22%, P = .002, tenderness 71% vs 5%, P = .003; strength (wrist and middle finger extension combined) 79% vs 15%, P = .011.

DISCUSSION

All outcome measures for chronic lateral epicondylosis were markedly improved with the addition of an eccentric wrist extensor exercise to standard physical therapy. This novel exercise, using an inexpensive rubber bar, provides a practical means of adding isolated eccentric training to the treatment of chronic lateral epicondylosis.

Electromyographic activity of selected scapular stabilizers during glenohumeral internal and external rotation contractions

HYPOTHESIS

An important synergistic relationship exists between the scapular stabilizers and the glenohumeral rotators. Information on the relative contribution of the scapular stabilizers to glenohumeral rotation would be useful for exercise prescription for overhead athletes and for patients with shoulder pathology. We hypothesized that the scapular stabilizers would be highly active during both maximal and submaximal internal and external rotation.

MATERIALS AND METHODS

Eight healthy male volunteers (16 shoulders) performed internal and external glenohumeral rotation testing at maximal and submaximal intensities. They also performed a scapular retraction rowing exercise at maximal and submaximal levels. Electromyographic (EMG) signals were recorded from the infraspinatus, pectoralis major, serratus anterior, and middle trapezius. Values were compared among muscle groups, among individual muscles at different intensity levels, and among individual muscles at different points in the arc of motion.

RESULTS

For submaximal glenohumeral internal rotation, activity in the scapular stabilizers was not different (P = .1-.83) from activity in the internal rotator throughout the range of motion. For the initial two-thirds of maximal internal rotation, middle trapezius activity and pectoralis major activity were higher (P < .05) than serratus anterior activity. For submaximal external rotation, activity in the scapular stabilizers during the middle phase of the motion was higher (P < .05) than activity in the external rotators. For maximal external rotation these differences were present throughout the motion with middle trapezius activity exceeding 100% maximal voluntary contraction.

CONCLUSIONS

The scapular stabilizers functioned at a similar or higher intensity than the glenohumeral rotators during internal and external rotation. This highlights the importance of training the scapular stabilizers in upper extremity athletes and in patients with shoulder pathology.

Correction of posterior shoulder tightness is associated with symptom resolution in patients with internal impingement

BACKGROUND

Glenohumeral internal rotation deficit (GIRD) and posterior shoulder tightness have been linked to internal impingement.

PURPOSE

To determine if improvements in GIRD and/or decreased posterior shoulder tightness are associated with a resolution of symptoms.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Passive internal rotation and external rotation (ER) range of motion (ROM) at 90 degrees of shoulder abduction and posterior shoulder tightness (cross-chest adduction in side lying) were assessed in 22 patients with internal impingement (11 men, 11 women; age 41 +/- 13 years). Treatment involved stretching and mobilization of the posterior shoulder. The Simple Shoulder Test (SST) was administered on initial evaluation and discharge. Changes in GIRD, ER ROM, and posterior shoulder tightness were compared between patients with complete resolution of symptoms versus patients with residual symptoms using independent t tests.

RESULTS

Patients had significant GIRD (35 degrees), loss of ER ROM (23 degrees), and posterior shoulder tightness (35 degrees) on initial evaluation (all P < .01). Physical therapy (7 +/- 2 weeks; range, 3-12 weeks) improved GIRD (26 degrees +/- 14 degrees; P < .01), ER ROM loss (14 degrees +/- 20 degrees), and posterior shoulder tightness (27 degrees +/-19 degrees). The SST improved from 5 +/- 3 to 11 +/- 1 (P < .01). A greater improvement in posterior shoulder tightness was seen in patients with complete resolution of symptoms (n = 12) compared with patients with residual symptoms (35 degrees vs 18 degrees; P < .05). Improvements in GIRD and ER ROM loss were not different between groups (GIRD, 25 degrees vs 28 degrees, P = .57; ER ROM, 14 degrees vs 15 degrees, P = .84).

CONCLUSION

Resolution of symptoms after physical therapy treatment for internal impingement was related to correction of posterior shoulder tightness but not correction of GIRD.

A new surgical technique for arthroscopic repair of the meniscus root tear

Injury of the meniscal root can lead to meniscal extrusion and loss of normal hoop stress distribution by the meniscus. This has been shown to result in an excessive tibiofemoral contact pressures and has been associated with development of arthritis in the affected compartment of the knee. Repair of meniscal root avulsion has been shown to restore the normal contact stresses, and several techniques for such repair have been described. We report an all-arthroscopic technique that allows anatomic reattachment of the avulsed meniscal root, applicable to both the medial or lateral menisci. Our technique utilizes a novel retrograde reaming device to create a small intraosseous socket at the meniscal tibial attachment, and may be particularly useful for repairing meniscal root avulsions in knees with multiligamentous injuries.

Biomechanical comparison of a knotless suture anchor with standard suture anchor in the repair of type II SLAP tears

PURPOSE

To compare the biomechanical strength of knotless suture anchors and standard suture anchors in the repair of type II SLAP tears.

METHODS

Five pairs of cadaveric shoulders (10 shoulders) were dissected free of soft tissue except for the glenoid labrum and long head of the biceps tendon. Type II SLAP tears were created and repaired with 1 of 2 anchors: the Mitek Lupine suture anchor or the Mitek Bioknotless suture anchor (DePuy Mitek, Raynham, MA). All specimens were preloaded to 10 N, and loaded for 25 cycles in 10 N increments to a maximum of 200 N. If specimens were still intact after 200 N, they were loaded to ultimate failure. The load at which 2 mm of gapping occurred, load to ultimate failure, mode of failure, and the number of cycles to failure were compared using the Wilcoxon signed-rank test.

RESULTS

Load to 2-mm gapping was lower (P = .042) for knotless anchors (70 N) versus knotted anchors (104 N), with similar differences for ultimate failure (74 N v 132 N; P = .043), cycles to 2-mm gapping (133 v 219 cycles; P = .042), and cycles to failure (143 v 297; P = .043). Eight of 10 specimens failed at the soft tissue interface (4 knotless, 4 knotted) and 2 failed by anchor pullout (1 knotted, 1 knotless).

CONCLUSIONS

The results of this study suggest that repair of a type II SLAP with a Mitek knotted suture anchor and mattress suture configuration through the biceps anchor is stronger than repair with a Mitek knotless suture anchor. The most likely method of repair failure was at the suture-soft tissue interface regardless of the type of anchor used. The application of a suture anchor that requires arthroscopic knot tying may be preferable to a knotless anchor for the surgical repair of type II SLAP tears.

CLINICAL RELEVANCE

Repair of type II SLAP tears with knotless suture anchors may allow for the avoidance of arthroscopic knot tying but is weaker than repair with standard suture anchors.

Cyclic loading of 3 Achilles tendon repairs simulating early postoperative forces

BACKGROUND

The abstract goes here and covers two columns. Accelerated rehabilitation has been advocated after Achilles tendon repair, but it produces significant forces at the repair site. The abstract goes here and covers two columns.

HYPOTHESIS

Stresses applied to the repaired Achilles tendon simulating postoperative forces may exceed the strength of some repairs.

STUDY DESIGN

Controlled laboratory study.

METHODS

Fifteen Achilles tendons were incised 4 cm proximal to the calcaneal insertion, then were repaired using either a percutaneous, 4-strand Krackow, or an epitendinous augmented 4-strand Krackow technique. Tendons were cyclically loaded to 1000 cycles each at 100, 190, and 369 N. The number of cycles to initial gapping, 5-mm gapping, and total failure were compared using Mann-Whitney U tests with adjustments for multiple comparisons.

RESULTS

Gap resistance was significantly greater for augmented Krackow repairs (2208 cycles to initial gapping) versus nonaugmented repairs (502 cycles, P = .024) and for nonaugmented Krackow repairs versus percutaneous repairs (5 cycles, P = .024). All percutaneous repairs failed during the 100-N cycling (102 +/- 135 cycles). All nonaugmented Krackow repairs failed during the 190-N cycles (total cycles to failure: 1268 +/- 345). All augmented Krackow repairs were intact (no gapping) after the 190-N cycles. Four failed during 369-N cycling (total cycles to failure, 2017 +/- 11), and 1 remained intact for 3000 cycles.

CONCLUSION

Epitendinous cross-stitch weave augmentation of Achilles tendon repairs significantly increased repair strength and gap resistance.

CLINICAL RELEVANCE

Epitendinous cross-stitch weave augmentation of Achilles tendon repairs may better allow for early stretching and ambulation after Achilles tendon repair.

Muscle strength and range of motion in adolescent pitchers with throwing-related pain: implications for injury prevention

BACKGROUND

A high prevalence of throwing-related shoulder and elbow pain has been documented in adolescent baseball pitchers.

HYPOTHESIS

Pitchers with a history of throwing-related pain will have weakened dominant-arm posterior shoulder musculature and greater dominant-arm glenohumeral total range of motion (ROM) loss compared with pitchers without throwing-related pain.

STUDY DESIGN

Controlled laboratory study.

METHODS

Twenty-three adolescent pitchers (age 15.7 +/- 1.4 years) were tested. Twelve pitchers had throwing-related pain in the prior season and were currently symptom-free, while the remaining 11 pitchers had no such history of pain. Internal and external rotation ROM and muscle strength (lower trapezius, middle trapezius, rhomboids, latissimus dorsi, supraspinatus, internal rotators, external rotators) were measured bilaterally. Dominant versus nondominant differences in ROM and strength were compared between pitchers with and without throwing-related pain.

RESULTS

As a whole, the group of 23 pitchers had a loss of internal rotation ROM (13 degrees +/- 10 degrees , P < .001) and gain in external rotation ROM (11 degrees +/- 10 degrees , P < .001) on the dominant versus nondominant arm, with no effect on total ROM (2 degrees +/- 7 degrees loss, P = .14). There was no difference in bilateral comparison of total ROM between pitchers with and without throwing-related pain. Dominant versus nondominant muscle strength was lower (P < .05) for the pain group versus nonpain group for the middle trapezius (7% +/- 19% vs 22% +/- 12%) and supraspinatus (-4% +/- 27% vs 14% +/- 14%) and higher (P < .05) for the internal rotators (19% +/- 14% vs 6% +/- 12%).

CONCLUSION

Throwing-related pain in this population may be due to the inability of weakened posterior shoulder musculature to tolerate stress imparted on it by adaptively strengthened propulsive muscles.

CLINICAL RELEVANCE

Selective posterior shoulder strengthening may be indicated in rehabilitative and injury prevention programs for adolescent pitchers.

Cyclical loading of coracoclavicular ligament reconstructions: a comparative biomechanical study

BACKGROUND

Reconstruction for injuries to the acromioclavicular joint remains controversial.

HYPOTHESIS

A coracoclavicular ligament reconstruction with a semitendinosus tendon would have superior performance to the classic coracoacromial ligament transfer with or without augmentation.

STUDY DESIGN

Controlled laboratory study.

METHODS

Five cadaveric shoulders were used to reconstruct the coracoclavicular ligaments with 3 methods: coracoacromial ligament transfer without augmentation, coracoacromial ligament transfer augmented with No. 5 Ethibond suture, and a semitendinosus tendon. Each reconstruction was cyclically loaded at 40 N to 80 N for 2500 cycles, then from 40 N to 210 N for 2500 cycles, followed by loading to failure. The number of cycles to 50% and 100% loss of acromioclavicular joint reduction were recorded.

RESULTS

During the 40 N to 80 N-loading cycle, the coracoacromial transfer without augmentation failed (15 +/- 16 cycles). The augmented coracoacromial ligament transfer and the semitendinosus reconstruction did not fail (P = .008). During the 40 N to 210 N-loading cycle, the augmented coracoacromial ligament transfer failed (207 +/- 399 cycles). The semitendinosus reconstruction survived through both loading cycles (P < .01).

CONCLUSION

Coracoclavicular ligament reconstruction with a semitendinosus graft is a biomechanically superior construct in a cyclically loaded setting to a coracoacromial ligament transfer augmented with a No. 5 Ethibond suture.

CLINICAL RELEVANCE

The semitendinosus graft is a strong, biologic option for reconstruction of the coracoclavicular ligaments.

Optimizing Achilles tendon repair: effect of epitendinous suture augmentation on the strength of achilles tendon repairs

BACKGROUND

Epitendinous suture augmentation has been shown to increase gap resistance and overall strength in flexor tendon repairs of the hand. The purpose of this study was to evaluate the effect of various suture augmentation techniques in Achilles tendon repair.

MATERIALS AND METHODS

Eighteen fresh-frozen cadaveric Achilles tendons were transected and repaired with a 4-strand Krackow core stitch. Suture augmentation was performed with 3 figure-of-eight stitches in 6 specimens and a running cross-stitch weave in 6 specimens. The other 6 specimens were not augmented. Each tendon was loaded to failure on an MTS. Force to failure (defined as peak force or force at 5 mm gapping), gapping resistance, stiffness, and elongation were compared.

RESULTS

Force to failure (p < 0.001), stiffness (p < 0.01) and gapping resistance (p < 0.05) were increased by suture augmentation. Additionally failure force and gapping resistance for the cross-stitch augmentation was higher than the figure-of-eight augmentation (p < 0.05).

CONCLUSION

Cross-stitch augmentation of Achilles tendon repair yields a stronger and stiffer repair with greater resistance to gapping.

CLINICAL RELEVANCE

Achilles tendon repairs augmented with a cross stitch weave will be able to withstand substantially higher forces than non-augmented repairs.

Rehabilitation of extra-articular sources of hip pain in athletes

Among people who participate in sports, extra-articular soft tissue injuries around the hip are common. The hamstring, quadriceps, adductor, and abductor muscle groups are often the site of soft tissue injury. Overlapping conditions make it difficult to identify the primary cause of hip pain and dysfunction. A proper evaluation and diagnosis of the impairment are crucial for the selection of interventions and quick return to play. The purpose of the clinical commentary is to present an evidence based stepwise progression in the evaluation and treatment of several common soft tissue injuries of the hip.

Clinical outcomes of coracoclavicular ligament reconstructions using tendon grafts

BACKGROUND

Numerous techniques for reconstruction of the coracoclavicular ligaments have been developed to treat acromioclavicular joint separations. A new, stronger method to reconstruct the coracoclavicular ligaments using semitendinosus tendon allografts has been previously described. No outcome studies have been published on this new procedure.

HYPOTHESIS

Reconstruction of the coracoclavicular ligaments using tendon grafts produces excellent functional results.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Nine patients underwent coracoclavicular ligament reconstruction using augmented cadaveric semitendinosus tendon allografts after a grade V acromioclavicular separation. All patients were evaluated for range of motion, strength, closed kinetic chain testing, the American Shoulder and Elbow Surgeons Rating Scale, Pennsylvania Shoulder Score, the Simple Shoulder Test, and the Acromioclavicular Joint Separation Questionnaire. Preoperative and postoperative radiographs were compared.

RESULTS

Range of motion measurements were normal in all motions except a loss of 5 degrees +/- 4 degrees (P < .05) in extension. No significant strength deficits were found. Functional closed kinetic chain tests scored comparatively to standardized norms. American Shoulder and Elbow Surgeons Rating scores were 96 +/- 5 out of 100; the Pennsylvania Shoulder Scale scores were 97 +/- 3 out of 100; the Simple Shoulder Test scores were 11.6 +/- 0 out of 12; and Acromioclavicular Joint Separation Questionnaire scores were 28 +/- 3 out of 31. Subjects reported an overall subjective satisfaction of 89% +/- 7%. Postoperative radiographs showed no loss of reduction of the acromioclavicular joint in any patient.

CONCLUSION

Outcome for coracoclavicular ligament reconstructions using augmented semitendinosus tendon grafts was excellent with full recovery of strength, minimal range of motion loss, and no clinical or radiographic loss of reduction of the acromioclavicular joint.

CLINICAL RELEVANCE

This procedure provides an excellent treatment for grade V acromioclavicular separations.