Terese L. Chmielewski

Biomechanical evidence supporting a differential response to acute ACL injury

OBJECTIVE To describe movement patterns in people with complete anterior cruciate ligament rupture objectively identified as good candidates for non-operative management of the injury. DESIGN Involved side kinematics and kinetics were compared to the uninvolved side and to uninjured subjects. BACKGROUND High-level athletes with anterior cruciate ligament rupture and poor dynamic stability (non-copers) have movement alterations, including less knee flexion and a decreased internal knee extensor moment during loading response, that are not seen in those with excellent knee stability (copers). Our screening exam can identify people with good rehabilitation potential for non-operative management of anterior cruciate ligament injury (potential copers), but the movement strategies of these individuals are unknown. METHODS Sagittal plane kinematics and kinetics during the stance phase of walking and jogging were collected from 11 subjects who had an acute anterior cruciate ligament rupture and met the criteria of the screening exam, and were compared to 10 uninjured subjects, who we studied previously. Variables were those in which non-copers differed from uninjured subjects. RESULTS The potential copers flexed their involved knee less than uninjured subjects and their uninvolved side during walking. Potential copers, compared to uninjured subjects, also had a lower vertical ground reaction force during loading response, a lower knee support moment, and an increased ankle support moment during walking. In jogging, the involved knee angle at initial contact was more extended compared to uninjured subjects, and the amount of knee flexion was less than the uninvolved side. No differences in kinetics were present during jogging. CONCLUSIONS This study provides evidence that the potential copers identified by the screening examination have movement patterns that are consistent with people who have more knee stability than non-copers. RELEVANCE Although potential copers have developed some characteristics of a successful stabilization strategy, the presence of kinematic alterations indicates that they may benefit from training programs designed to enhance dynamic knee stability.

Development of dynamic knee stability after acute ACL injury

Recently, a training program that includes perturbation of support surfaces has been shown to allow most active individuals with ACL injury who pass a screening examination to successfully return to high level activities. The purpose of this study was to identify the effect of this rehabilitation program on involved side muscle activation during walking in subjects with acute ACL rupture and to determine if the activation changes were coincident with improved function. Nine subjects with an acute, unilateral ACL injury or rupture of an ACL graft, who met the screening examination criteria, received ten sessions of rehabilitation that included perturbation training. Motion analysis of five self-paced walking trials were performed before and after training. Electromyographic (EMG) data were collected during stance. After training during walking, the vastus lateralis (VL) integral of activity increased, and relationships between muscles were significantly altered. During walking, VL activation variables were dependent on lateral hamstrings (LH) and/or the soleus (SOL) activation, while no relationships were found before training. Function improved after training, and all subjects returned to their pre-injury activities without experiencing instability. The relationships formed between muscles post-training suggests that perturbation training enhances dynamic knee stability by inducing a well-coordinated strategy among muscles that affect tibial translation.

A prospective analysis of incidence and severity of quadriceps inhibition in a consecutive sample of 100 patients with complete acute anterior cruciate ligament rupture

Background: Weakness of the quadriceps femoris muscle after anterior cruciate ligament (ACL) injury and reconstruction has been attributed to incomplete voluntary activation of the muscle. The literature is conflicting on the incidence of incomplete voluntary quadriceps activation after ACL injury because of differences in testing methods and population biases. The purpose of this study was to systematically examine the incidence and severity of quadriceps voluntary activation failure in both lower extremities after acute ACL injury. We hypothesized that the incidence of quadriceps inhibition would be higher in the ACL‐injured limbs than the uninvolved limbs, that the incidence of inhibition in the ACL‐deficient limbs would be larger than in our historical sample of healthy young individuals tested in the same manner and that there would be no difference in inhibition by gender.

Rehabilitation of Elbow Injuries in Overhead-throwing Athletes

The athlete who uses the overhead motion can sustain numerous injuries to the elbow joint complex. The differential diagnosis of the specific disorder is vital to a successful outcome and to establish a proper nonoperative rehabilitation program. Thus, specific rehabilitation programs and time frames for the nonoperative treatment of various elbow injuries are available. In this chapter, we discussed nonoperative treatment for several common elbow injuries. The physician must communicate with the rehabilitation specialist regarding the differential diagnosis, rehabilitation program, and expected outcome. Many elbow maladies can be successfully managed nonoperatively. When nonoperative treatment fails, further clinical examination, diagnostic testing, and, possibly, surgical intervention are necessary.

Movement patterns of individuals with good potential to dynamically stabilize their knees after acute ACL rupture

Previous work in our lab has demonstrated that a screening tool can be beneficial in selecting patients with anterior cruciate ligament (ACL) rupture for return to high-level activities through non-operative management [1].The screening tool uses clinical tests to differentiate those who have the potential to dynamically stabilize their knee from those who cannot. Patients selected by the screening tool (potential copers) have greater success in returning to high-level activities without knee instability compared to either those who do not meet the criteria, or uncategorized subjects [1,5,6].

Neuromuscular control of the ACL deficient knee: Implications for the development of osteoarthritis

Many of the estimated 100,000-200,000 individuals who annually sustain anterior cruciate ligament (ACL) injuries in the USA experience substantial knee joint instability that could lead to joint deterioration over time [1, 2, 3]. Those who do not cornpensate well for ACL rupture (non-copers) comprise the majority of those who sustain this injury and the majority of those who undergo reconstructive surgery in the early post-injury period [4,5].ACL deficiency is associated with episodes of “giving way” of the knee that likely lead to excessive shear forces in the joint and uneven joint loading [6].Shear forces are particularly detrimental to articular cartilage [7].We have shown that joint instability and quadriceps femoris weakness, ubiquitous in non-copers, precipitate movement compensations that include reduced knee motion, reduced knee moment and excessive muscle co-contraction. Recently, Ramsey and colleagues, using markers attached to bone via intercortical pins, extended this finding to measurements of anterior translation during jumping in four ACL deficient non-copers ([8]and DK Ramsey, personal communication 1/24/01). The non-copers in their study over-constrained the knee, keeping the tibial translation below even that of their uninjured knees. This stiffening strategy, which persists over a wide range of activities, reflects an unsophisticated adaptation to the ACL rupture for which appropriate muscle activation strategies have not yet developed [9, 10].This compensation strategy, which may reduce the anterior tibial translation at the knee, may also lead to less shock absorption and excessive joint compression that exacerbate joint destruction [4,9,10].Compression and shear forces contribute significantly to the biochemical and metabolic changes that characterize degeneration of articular cartilage [2].Most individuals with chronic ACL deficiency develop knee OA years after injury [11].