Rotational laxity greater in patients with contralateral anterior cruciate ligament injury than healthy volunteers.

Rotational stability of the knee has been traditionally difficult to quantify, limiting the ability of the orthopedic community to determine the potential role of rotational laxity in the etiology of anterior cruciate ligament (ACL) injuries. The purposes of this multicenter cohort study were to evaluate the reliability of a robotic axial rotation measurement system, determine whether the uninjured knees of patients that had previous contralateral ACL reconstruction demonstrated different rotational biomechanical characteristics than a group of healthy volunteers, and determine whether knee rotational biomechanical characteristics differ between male and female non-injured limbs in groups of both healthy volunteers and patients with a previous contralateral ACL injury. Fourteen healthy volunteers and 79 patients with previous unilateral ACL injury participated in this study. Patients were tested using a computerized tibial axial rotation system. Only the normal (non-operated) knee data were used for analysis. In order to assess the reliability of the robotic measurement system, 10 healthy volunteers were tested daily over four consecutive days by four different examiners. Rotational laxity and compliance measures demonstrated excellent reliability (ICC = 0.97). Patients with a contralateral ACL injury demonstrated significantly increased tibial internal rotation (20.6° vs. 11.4°, P < 0.001) and reduced external rotation (16.7° vs. 26.6°, P < 0.001) compared to healthy volunteers. Females demonstrated significantly increased internal and external rotation, as well as significantly increased rotational compliance compared with males (P < 0.05). Computer-assisted measurement techniques may offer clinicians an accurate, reliable, non-invasive method to select the most appropriate preventative or surgical interventions for patients with increased knee rotational laxity.

MPFL reconstruction for PF instability. The soft (tissue) approach.

Historically, anatomic factors have been identified that increase one's risk for episodic lateral patella dislocations. A surgical treatment algorithm has been proposed which utilizes these risk factors. This algorithm depends primarily on realignment of the bony architect. Increasingly, the soft tissue retinacular restraints have been shown to be important as an anatomic factor critical for patellofemoral stability; in particular, the medial patellofemoral ligament (MPFL) has been recognized as the essential stabilizer against lateral patella displacement. Current indications for MPFL reconstructions will be reviewed. The frequency of reconstructing the MPFL alone versus combining it with other realignment schemes in my last 30 patients will be presented.

Anterior cruciate ligament injuries.

Increasingly, epidemiological data has shown differences in the total number of injuries and in the incidence of serious knee injuries among males and females in jumping and pivoting activities. Particularly, strong epidemiological data support increased incidence of non-contact anterior cruciate ligament injuries in females. Despite more than a decade of vigorous debate and intense study on this topic, research has yet to clearly link gender as an individual risk factor for this injury. Risk factors can be divided into intrinsic or extrinsic factors; for this review they are divided into anatomic, hormonal, and neuromuscular categories. The most intriguing of these deals with neuromuscular control of the limb. In particular, neuromuscular issues involving hip and trunk position and its muscular control have been increasingly implicated in this injury etiology. Gender differences have been found in motion patterns, positions, and muscular forces generated with various lower extremity coordinated activities. Thus, many clinicians currently advocate a strengthening program that emphasizes proximal hip control mediated through gluteus and proximal hamstring activation in a close chain fashion. This, combined with skill training in landing and pivoting maneuvers, is thought to help prevent injury. We must encourage continued, structured, and focused research in this area. However, until specific predictive and protective factors are identified, training and prevention programs should continue to be implemented, assessed, and improved.

Noncontact anterior cruciate ligament injuries: risk factors and prevention strategies.

An estimated 80,000 anterior cruciate ligament (ACL) tears occur annually in the United States. The highest incidence is in individuals 15 to 25 years old who participate in pivoting sports. With an estimated cost for these injuries of almost a billion dollars per year, the ability to identify risk factors and develop prevention strategies has widespread health and fiscal importance. Seventy percent of ACL injuries occur in noncontact situations. The risk factors for non-contact ACL injuries fall into four distinct categories: environmental, anatomic, hormonal, and biomechanical. Early data on existing neuromuscular training programs suggest that enhancing body control may decrease ACL injuries in women. Further investigation is needed prior to instituting prevention programs related to the other risk factors.

Anterior knee pain in females.

There are clear differences between men and women regarding anterior knee pain. Anatomic factors including increased pelvic width and resulting excessive lateral thrust on the patella are primary factors that predispose females to anterior knee pain. Effects of estrogen on connective tissue synthesis have been reported, but there is no clear mechanism by which this would affect anterior knee pain. Postural and sociologic factors such as wearing high heels and sitting with legs adducted can influence the incidence and severity of anterior knee pain in women.

Stress fractures and the female athlete.

Stress injury to bone is the result of a temporary disturbance in the equilibrium between bone resorption and bone regeneration. Knowledge of the pathophysiology of bone in health and disease currently encompasses an interactive mode that includes biomechanical, hormonal, nutritional, and genetic factors. The current study will review possible etiologic theories for stress injuries to bone with a special emphasis on gender-related factors. Females may be more at risk for a stress injury to bone because of their unique hormonal environment, and other anatomic and gender factors.

The female knee--anterior knee pain.

There are clear differences between men and women with regard to anterior knee pain. Anatomic factors including increased pelvic width and the resulting excessive lateral thrust on the patella are significant in female predisposition to anterior knee pain. Effects of estrogen on connective tissue synthesis have been noted, but there is no clear mechanism by which this would affect anterior knee pain. Postural and sociologic factors such as wearing high heels and sitting with legs adducted can influence the incidence and severity of anterior knee pain in women.

Anterior cruciate ligament injury patterns among collegiate men and women.

OBJECTIVE: To determine potential patterns that cause males and females to tear the anterior cruciate ligament (ACL) while playing basketball or soccer. DESIGN AND SETTING: We reviewed data submitted to the National Collegiate Athletic Association Injury Surveillance System over the last 10 years, as well as profile data collected from collegiate certified athletic trainers. SUBJECTS: College athletes involved in basketball or soccer. MEASUREMENTS: Historical information was collected on those athletes involved in the National Collegiate Athletic Association Injury Surveillance System. Athletes involved in the profiling study underwent physical measurements related to flexibility, as well as a more detailed history relating to the ACL tear. RESULTS: College-age women involved in basketball or soccer tear their ACLs at significantly higher rates than college-age men involved in the same sports. No distinct physical or historical measurements could be attributed to this different rate of injury. CONCLUSIONS: Although the higher rate at which women compared with men tear their ACLs has persisted over the last 10 years, this increased incidence is not clearly attributable to any physical or historical measurements that were monitored.

The use of MR imaging in the assessment and clinical management of stress reactions of bone in high-performance athletes.

Based on experience, the authors believe that MR imaging is a useful tool in the assessment and management of stress fractures and stress phenomenum of bone. The use of standard, graded MR evaluation aides the assessment of a repetitive stress injury to bone by allowing a more accurate diagnosis of bone injury. This more accurate assessment has predictive value in estimating the duration of disability. The use of a standard, graded MR evaluation aides the management of repetitive stress injuries to bone by defining a low grade of stress fracture (i.e., grade 1 and 2) injuries and a high grade of stress fracture (i.e., grade 3 and 4). This grading system has implications in the management of stress fractures, allowing more individualized treatment for the elite athlete.

Common musculoskeletal injuries in women.

The causes of women's sports injuries are currently a topic of vigorous speculation in sports medicine. Research has yet to clearly link gender to any injury etiology. Meanwhile, physicians are analyzing gender differences to find ways that women can better condition themselves for sports, avoid injuries, and recover quickly from the injuries that do occur. An analysis of the most common problems active women face (anterior cruciate ligament, patellofemoral, shoulder, and foot injuries) suggests effective strategies for diagnosis, treatment, rehabilitation, and prevention.

Orthopaedic issues for active and athletic women.

The last quarter century has witnessed great change in the participation and abilities of female athletes. Many myths regarding the inability of women to participate in sport and recreational pursuits are being dispelled. Whereas there is still much to learn about the potential and limitations of female athletes, education concerning that which is already known should be a goal. It is only through education of those caring for female athletes and their families, and education of the athletes themselves, can one hope to have all women pursue and reach their full athletic potential safely.

Catheter with an anchoring tip for chronic joint capsule perfusion.

An orthopedic catheter for long-term access to the synovial joint is anchored by a hollow threaded tap that penetrates the capsule through a hole drilled in the surrounding bone. The proximal end of the catheter is connected to either an implantable drug infusion pump or an implantable access port for continuous or intermittent perfusion or sampling. Four catheters were evaluated in dogs. Three were attached to ports, the fourth to a pump. Water (one trial, 22 weeks) and hyaluronic acid (HA) (5 mg/ml; two trials of 8 weeks each) were administered through ports twice weekly in 1.5 ml boluses; 5 mg/ml HA was delivered by pump (1 trial of 33 weeks) at 0.31 ml/day.

31P-NMR study of normoxic and anoxic perfused turtle heart during graded CO2 and lactic acidosis.

We studied the effects of graded acidosis (both CO2 and lactic acid) and anoxia on intracellular pH (pHi) regulation, high-energy phosphates, and mechanical function of isolated perfused hearts of the turtle (Chrysemys picta bellii) at 20 degrees C using 31P-nuclear magnetic resonance (NMR) spectroscopy. During CO2 acidosis, anoxia had no effect on apparent nonbicarbonate buffer value (d[HCO3-]/dpHi = 71 and 89 mM/pH in normoxia and anoxia, respectively) or on pHi regulation (dpHi/dpHe = 0.52 and 0.43 in normoxia and anoxia, respectively, where pHe is extracellular pH). During normoxic lactic acidosis, dpHi/dpHe was similar to the values observed in CO2 acidosis and averaged 0.55 overall. During anoxic lactic acidosis, however, similar regulation occurred over only a narrow range of pHe, and then dpHi/dpHe increased to greater than 1.0 at pHe less than 7.1. Creatine phosphate (CP), calculated as the area of the NMR peak, fell more in response to normoxic CO2 acidosis than to normoxic lactic acidosis; in anoxia, the fall in CP was further increased but to similar extreme levels (10-20% of control) in both acid perfusions. Cardiac output and maximum rate of pressure development each fell during acidosis in similar fashion in all protocols, and the responses were similar in normoxic and anoxic hearts. Heart rate, in contrast, decreased during acidosis, but this effect was more pronounced when hearts were anoxic. We conclude that the effect of acidosis on cardiac function can depend on the type of acidosis imposed. Based on the heart's insensitivity to anoxia alone, we suggest that anoxia may normally depress function indirectly via its effect on intracellular acid-base state.

31P-NMR measurements of pHi and high-energy phosphates in isolated turtle hearts during anoxia and acidosis.

We used 31P-nuclear magnetic resonance (NMR) spectroscopy to measure intracellular pH (pHi) and high-energy phosphate levels in hearts of turtles (Chrysemys picta bellii) during either 4 h of anoxia [extracellular pH (pHo) 7.8, 97% N2-3% CO2], 4 h of lactic acidosis (pHo 7.0, 97% O2-3% CO2), or 1.5 h of combined anoxia + lactic acidosis (pHo 7.0, 97% N2-3% CO2) followed by 2 h of oxygenated recovery (pHo 7.8) at 20 degrees C. We also measured heart rate, maximum ventricular-developed pressure, and rate of pressure development (dP/dtmax). 31P-NMR spectra were characterized by the seven peaks typical of mammalian hearts, although turtle spectra were dominated by a large phosphodiester peak. Anoxia caused an increase in Pi to 165% and a decrease in creatine phosphate (CP) to 42% of control, whereas ATP levels remained unchanged. pHi declined from 7.37 +/- 0.01 to 7.22 +/- 0.03 at 1 h of anoxia and remained unchanged through hour 4. Lactic acidosis caused a 59% decrease in Pi, whereas CP and ATP levels remained unchanged. pHi fell to 6.88 +/- 0.04 by hour 1 and then climbed steadily to 7.14 +/- 0.05 at hour 4. During recovery from acidosis, pHi exceeded control values and returned to control by 2 h. Combined anoxia + acidosis caused profound decreases in CP to 14% and pHi to 6.56 +/- 0.03. In anoxic hearts, cardiodynamic variables remained at control levels through hour 3, after which cardiac output, heart rate, and dP/dtmax declined. Cardiodynamic variables were essentially unchanged from control throughout 4 h of acidosis except for dP/dtmax, which declined rapidly. In the combined protocol, all measures of cardiac function decreased. Recovery in all three cases was complete by approximately 2 h. We conclude that turtle hearts were relatively resistant to the stresses imposed in all three protocols compared with mammalian hearts, although anoxia + acidosis depressed the measured cardiac variables more profoundly than predicted from responses to the conditions imposed separately. Our results from the anoxia protocol suggest no direct causal relationship between myocardial CP (or ATP) levels and cardiac function.

Vascularized patella tendon anterior cruciate ligament reconstruction.

Forty-seven patients with a chronic anterior cruciate ligament (ACL) deficiency were treated with patella tendon ACL reconstructions from July 1980 to September 1983. All patients had a minimum two-year follow-up period (range, 24-54 months). Forty-two patients (89%) had meniscal damage in association with the ACL deficiency. This included seven menisci (17%) that had a stable tear and were left in place without suture fixation. Only five patients (11%) had normal menisci at the time of reconstruction. Functional and subjective results were obtained from a questionnaire that included a comprehensive evaluation of patients' symptoms and activities. Objective results were analyzed on the basis of a thorough physical examination, augmented with arthrometer instrumented drawer testing. The detailed questionnaire was returned by 42 patients (89%). Follow-up examinations were obtained for 37 patients (79%), with arthrometer testing of 35 patients (75%). A 100-point rating scale defined objective, subjective, and functional results. Stability testing, using Lachman's test, was judged to be less than or equal to 5 mm of anteroposterior tibiofemoral translation in 51% of the patients examined and less than or equal to 10 mm of translation in 89%. Stability by arthrometer testing was less than or equal to 5 mm side-to-side difference in 83%. No patient lost a menisci after reconstruction. This included six patients with stable tears that were left unsutured. Subjective results were good or better in 60%. Functional results were good or better in 52%, with 41 of 42 patients participating in some form of recreational sports postoperatively. There was a large discrepancy between objective findings and the subjective and functional results (14% poor results compared with 31% and 43%, respectively). Although objective stability could be surgically restored in an ACL-deficient knee, the quality of the knee at the time of reconstruction as well as the postoperative and rehabilitative regimen are implicated in patients with poor subjective and functional results.

Multidirectional shoulder instability.

Multi-directional shoulder instability is a difficult problem to both diagnose and treat. Knowledge of shoulder anatomy and its pathological states has expanded dramatically in recent years. Aiding diagnostic acumen are new tools including CT arthrograms, glenohumeral arthroscopy, and evaluation under anesthesia. MDI of the shoulder is increasingly recognized as a clinical entity. Diagnosing this problem demands great skill in correlating the history with the physical examination and radiographic procedures. Conservative treatment is the initial treatment of choice. Surgical treatment is exacting both in its preoperative assessment and surgical technique.

Muscle fiber types.

Muscle fiber can be typed according to histologic, biochemical, neurophysiologic, and ultrastructural differences. The relationship between muscle fiber typing and clinical areas of investigation is summarized. Genetic factors are largely responsible for the distribution of main muscle fiber types. Strength training produces relatively slight alterations in muscle properties, as defined by present analytic techniques. The functional adaptation of skeletal muscle are dependent on a multitude of factors, which at the present time are not completely understood.