Electromyographic activity of quadriceps muscle during sit-to-stand in patients with unilateral knee osteoarthritis.

OBJECTIVE: The sit-to-stand (STS) is a simple test to evaluate the functional performance of the quadriceps muscle in patients with knee osteoarthritis (OA). The aim was to evaluate the electromyographic (EMG) activity of the ipsilateral quadriceps during STS task at different seat heights and feet positions in patients with severe unilateral OA. The EMG activity was recorded in a group of eight participants with unilateral OA during the performance of STS task in four conditions: (1) knee-height seat with feet together, (2) knee-height seat with feet askew (feet side by side and heel-to-toe), (3) low-height seat (25% lower than knee-height seat) with feet together, and (4) low-height seat with feet askew. RESULTS: There was a statistically significant difference among the four conditions in the EMG activity (p =0.004). Particularly, the EMG activity of the quadriceps was significantly higher when participants rose from the low height with their feet askew than when they rose from the knee height with their feet placed together (p =0.004) or askew (p =0.002). These results recommend considering initial feet position and seat height when evaluating the functional activity of the quadriceps in patients with unilateral OA using STS test.

Comparison of isometric and anatomic reconstruction of the medial patellofemoral ligament: a cadaveric study.

Recent surgical procedures designed to correct recurrent posttraumatic lateral patellar instability focus on reconstructing the medial patellofemoral ligament. This study evaluated and compared patellofemoral kinematics of isometric and anatomic medial patellofemoral ligament reconstructions. Using an infrared motion capture analysis system, patellar tracking was evaluated in the coronal plane in 6 cadaveric specimens. Reconstruction of the medial patellofemoral ligament using an isometric technique did not restore normal patellar tracking at any flexion angle; however, reconstruction using an anatomic technique restored statistically normal patellar tracking from maximal knee extension to 28 degrees of flexion. Neither technique was able to restore normal kinematics in deeper angles of knee flexion.

Anatomic and radiographic analysis of arthroscopic tack placement into the superior glenoid.

PURPOSE: To anatomically and radiographically describe tack location within the anterosuperior (AS) and posterosuperior (PS) aspects of the glenoid when performing simulated repairs of type II SLAP lesions. TYPE OF STUDY: Cadaveric anatomic and radiographic analysis. METHODS: Arthroscopy was performed on 7 fresh-frozen cadaveric shoulders and bioabsorbable tacks were placed in the AS and PS aspects of the glenoid to simulate repair of a type II SLAP lesion. The PS tack was placed through an accessory portal 1 cm lateral and 1 cm anterior to the posterolateral corner of the acromion. Dissection was then performed, and the incision made in the rotator cuff when creating the posterolateral accessory portal (PLAP) was identified and measured. Tack location within the glenoid was visually studied after removal of all soft tissues and recorded as being either completely within bone or partially within bone. The tacks were recannulated with guide pins and 3 radiographs were then taken of each specimen (true anteroposterior, axillary, and en face glenoid views) and angles of entry determined. In addition, the angle of deviation from the orthogonal at the point of entry of each tack was measured on the en face glenoid view. RESULTS: The average incision made in the rotator cuff for creation of the PLAP measured 10.3 mm in maximum diameter. In 6 of 7 specimens, this incision was made through muscle and not tendon. Seven of 7 AS tacks were completely within bone, and only 5 of 7 PS tacks remained completely within bone. On the true anteroposterior view, the average angle of entry from the vertical for the AS tack was 64 degrees. For the PS tack, this angle measured 86 degrees. On the axillary view, the angle of placement from the coronal averaged 22 degrees for the AS tack and 42 degrees for the PS tack. For the en face glenoid view, the angle of entry from the vertical was 34 degrees for the AS tack and 93 degrees for the PS tack. Lastly, the angle of deviation from the orthogonal on the en face glenoid view was 12 degrees and 35 degrees for the AS and PS tacks, respectively. This difference was statistically significant at P <.001. CONCLUSIONS: This study provides quantitative data on the angle of placement and location of tacks within the superior glenoid when performing repairs of type II SLAP lesions. It also shows the PLAP to be a safe portal for the placement of devices into the posterosuperior aspect of the glenoid. Furthermore, the data show the AS tack to be more reliably placed than the PS tack.