Abstract: PURPOSE: The purpose of this study was to document the results of arthroscopic treatment for synovial chondromatosis of the shoulder with loose body removal and partial synovectomy. METHODS: Five cases of shoulder arthroscopy performed for synovial chondromatosis were reviewed. Removal of loose bodies and partial synovectomy was performed in all cases. Follow-up of 4 to 9 years was obtained on these 5 patients. RESULTS: The clinical result was very good for all patients. Radiologic signs of chondroma were observed in two patients. Revision surgery was not necessary in either case. CONCLUSIONS: The clinical results referring to the Constant and Murley score and subjective assessment were very good at 4 to 9 years following surgery. However, in two out of five subjects, radiographs revealed evidence of persisting or recurrent synovial chondroma at follow-up. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Abstract: To determine and compare the influence of 2 different approaches on quadriceps femoris muscle function in total knee arthroplasty (TKA), 20 patients (14 women, 6 men) with bilateral knee osteoarthritis underwent a 1-stage bilateral TKA. Surgical approaches (subvastus, midvastus) were performed by a random selection. Measurements of quadriceps voluntary activation and maximal voluntary contraction were estimated by a twitch interpolation technique before, 3 and 6 months after TKA. Knee pain was quantified by the Lewis Score. There was no difference between the 2 approaches at 3 and 6 months after TKA with regard to maximal voluntary contraction (P = 0.84, F = 0.041) and voluntary activation (P = .863, F = 0.031). In the subvastus group was a significantly higher knee pain until 6 months after surgery (P = .02). The subvastus approach for TKA does not provide any advantages compared with the midvastus approach with respect to the quadriceps femoris muscle strength in the early postoperative period. Furthermore, the subvastus approach caused significantly more pain postoperatively.

Abstract: PURPOSE: To investigate the midterm results of a standardized arthroscopic technique for labrum reconstruction by using a third suprabicipital portal for better visualization of the anterior glenoid rim. METHODS: Thirty-three of 36 patients treated for recurrent anterior shoulder dislocation were followed up by telephone and/or in clinical examinations. The average age of the patients (12 women and 21 men) at the time of surgery was 25.2 years, with a mean follow-up of 35 months. On average, 7.8 dislocations occurred between the first dislocation and the stabilization procedure (mean, 45.4 months). RESULTS: Two patients suffered again from redislocations (recurrence rate 6.1%), and 3 patients had 1 or 2 subluxations (9.1%) at the time of follow-up. In the Rowe score, the patients reached 77.5 points on average; 81.8% of the patients returned to sports and leisure activities as in the time before the first dislocation, and 18.2% (6 patients) did not. Limitations for external rotation were 7.8 degrees on average postoperatively. No statistical correlation between the number of preoperative dislocations and the level of the postoperative Rowe score was found. CONCLUSIONS: The arthroscopic labrum reconstruction with capsular shift using the 3-portal technique combined with a standardized suprabicipital camera position revealed a recurrence rate and midterm results that were close to results achieved after open procedures. The failure rate, according to the number of dislocations, was 6.1% based on the patient's satisfaction of 12.1%. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Abstract: Joint disease causes weakness and wasting of adjacent muscles, in part because of inability to fully activate these muscles voluntarily. Previous findings suggest that transcranial magnetic stimulation (TMS) paired with muscle contractions enhances maximal voluntary contraction force (MVC) in healthy subjects by improving voluntary activation (VA). The aim of the present study was to evaluate whether such an effect is also present in subjects suffering from diminished muscle force due to decreased VA. Three single TMS over resting motor threshold were applied in 10 patients with a mean age of 62 years after total-knee arthroplasty either during MVC or during muscle relaxation (control experiment) in a blinded randomized crossover study. MVC and VA were determined using a twitch-interpolation technique at 1, 15, 30, and 60 min after stimulation. There was a significant effect of TMS on MVC if applied in synchrony with muscle contraction, and this persisted for at least 60 min beyond stimulation. In patients suffering from joint disease, TMS might make physiotherapy more effective.

Abstract: BACKGROUND: The purpose of the study was to evaluate whether the postoperative depletion or the preoperative antithrombin (AT) activity is related to the occurrence of deep vein thrombosis (DVT) in patients receiving low-molecular-weight heparin for DVT prevention after elective hip replacement surgery. PATIENTS AND METHODS: In 93 patients AT-activity and standard laboratory parameter were determined on the preoperative day and daily for one week after operation. Furthermore, a color-coded compression sonography was performed before and 8-10 days after surgery. The amount of blood loss and blood transfusions was evaluated. Patients were divided into two groups in respect to the occurrence of a postoperative DVT. RESULTS: The overall incidence of DVT was 8.6% (n = 8). Patients with DVT had a significantly lower preoperative AT-activity (80.6 +/- 3.31%) compared to those without DVT (98.1 +/- 1.12%, p < 0.001), however, without being predictive for DVT (positive predictive value 0.71). There was no association between postoperative fall of AT, the lowest postoperative AT activity, blood loss or blood substitution and DVT. CONCLUSIONS: It has to be expected that a small fraction of patients for elective hip surgery present with AT-activity levels possibly being insufficient for a therapeutic effect of low-molecular-weight heparin even preoperatively. Those patients are subject to a significant higher risk of DVT postoperatively.

Abstract: It is well accepted that transcranial magnetic stimulation (TMS) can modulate motor cortex excitability long after application. Furthermore, a positive TMS effect on the ability to perform a maximal voluntary contraction (MVC) of the quadriceps femoris muscle has been described. However, stimulus strength dependence and duration of this effect are currently unknown. In the present study these parameters of the TMS-induced MVC enhancement were investigated in seven healthy subjects. Initially, three repetitive transcranial magnetic stimuli of varying stimulus strength were applied every 4 s either during MVC or relaxation. Thereafter, MVC and the ability to activate the quadriceps muscle voluntarily (voluntary activation) were determined using a sensitive twitch interpolation technique. In a second experiment we investigated the effect of three transcranial magnetic stimuli applied either during MVC or during relaxation on MVC over a time period of 30 min. There was a small but significant and stimulus strength related positive effect of TMS on MVC. The effect of TMS on voluntary activation was not significant. TMS had to be given during MVC to be effective and the positive effect of TMS when applied during MVC was still present after 30 min. These results indicate that TMS acts differently on the motor cortex depending on its activation status. TMS might have potential therapeutic applications in diseases associated with diminished cortical motor drive and subsequent muscle weakness.

Abstract: Central activation deficits have been recognised to be partially responsible for quadriceps muscle weakness after knee injuries effecting the injured as well as the uninjured leg. The purpose of this study was to assess the extent of bilateral activation deficits and its effect on functional muscle tests using the uninjured leg as reference. The study included 30 patients with isolated rupture of the anterior cruciate ligament (group 1), 42 patients with rupture of the anterior cruciate ligament and accompanying joint damage (group 2) and 34 healthy volunteers as reference. The maximum isometric knee extension torque and the maximal voluntary muscle activation (VA) were measured bilaterally using a sensitive twitch-interpolation method. The measured and the true functional deficit, adjusted to a physiological VA of the uninjured side, was calculated. Isolated rupture of the anterior cruciate ligament caused a minor VA-deficit and severe knee injuries more severe VA-deficits of the quadriceps muscles of the injured (VA group 1: 83.8 +/- 1.9 %; group 2: 76.9 +/- 1.8 %) and on the uninjured side (VA group 1: 85.9 +/- 1.8 %; group 2: 77.9 +/- 1.8 %) compared to the control group (VA 91 +/- 0.64 %). Due to contralateral VA-deficits the mean underestimation of the isometric muscle-force deficit was 22 % in group 1 and 48% in group 2. Unilateral knee injuries lead to significant VA-deficits of the quadriceps muscles on both the injured and uninjured legs related to the severity of injury. The validity of tests for the assessment of muscle function is questionable when using the uninjured side as reference.

Abstract: AIM: The reduction in quadriceps femoris muscle activation is considered to be one of the major mechanisms involved in pathological motion patterns in patients with osteoarthritis (OA) of the knee. These activation deficits are, at least in part, reversible after total knee arthroplasty (TKA). The purpose of this study was to investigate the effects of TKA on motion patterns in patients with OA of the knee. METHOD: 50 patients with knee OA were investigated prior and at 33 +/- 8 months after unilateral TKA. The control group comprised 17 healthy volunteers matched to the study group with respect to age. The gait analysis was performed with an optoelectronic motion analysis system (Elite(R), Italian). RESULTS: Step length, step duration and velocity increased after surgery (p < 0.05), but remained lower than the values of the controls (p < 0.05). Extension angles in stand and swing phase remained unchanged and significantly lower when compared to control values (p = 0.01, p = 0.04). Flexion angles in swing (p = 0.02) and stand phase (p = 0.01) increased on the operated side and were significantly higher than the flexion angle in the control group (p = 0.02, p = 0.03). Reextension in stand phase, which was investigated for quantification of functional range of motion, increased bilaterally after surgery (p < 0.01), but remained lower than the reextension of the controls (p </= 0.01). CONCLUSION: Although a significant improvement of pathological motion patterns in patients with OA of the knee after unilateral TKA occurred, a deficit persisted 33 +/- 8 months after surgery. The improvement of functional range of motion in stand phase was only caused by increased flexion. No influence was found with gait analysis on extension after TKA.

Abstract: OBJECTIVE: To evaluate the maximal voluntary contraction (MVC) force and the voluntary activation of the quadriceps femoris muscle in patients with knee osteoarthritis (OA) before and after total knee arthroplasty (TKA). DESIGN: A prospective intervention study. SETTING: University hospital clinic in Germany. PATIENTS: Fifty patients (32 women, 18 men; mean age +/- standard deviation, 65.8+/-5.6 y) with knee OA and 23 healthy age- and gender-matched control subjects. INTERVENTION: Unilateral TKA without patella resurfacing. MAIN OUTCOME MEASURES: Voluntary activation, MVC, and true maximal contraction forces of the bilateral quadriceps femoris muscles, using the twitch interpolation technique before and 33+/-8 months after TKA. Assessment of postoperative knee pain by the Lewis score. RESULTS: Voluntary activation increased bilaterally after surgery (P<.01 operated side, P=.02 nonoperated side) but remained lower than the voluntary activation of the controls. MVC (P<.001) and true maximal contraction forces (P=.01) increased significantly on the operated side. MVC remained unchanged (P=.45), and true maximal contraction forces decreased significantly (P=.04) on the nonoperated side. CONCLUSION: Patients with knee OA have significant bilateral voluntary activation deficits that are, at least in part, reversible within 3 years after TKA. Rehabilitation programs immediately after TKA should focus on reduction of voluntary activation deficits. After voluntary activation improves, physical therapy should target the augmentation of quadriceps femoris muscle strength.

Abstract: We describe a new arthroscopic technique to reinforce the torn inferior glenohumeral ligament (IGHL) and the elongated capsule to the glenoid rim. The arthroscope is inserted over the superior portal and, after the insertion of a suture anchor, both limbs are pulled out over the posterior portal. The IGHL is grasped and pulled upward onto the glenoid rim using a suture retriever clamp inserted over the posterior portal. A 45 degrees curved blunt clamp (Sidewinder; Arthrex, Naples, FL) coming from the anterior penetrates the IGHL, and 1 end of the suture limb is given into the branches of the clamp and pulled out anteriorly. After a second perforation of the capsule, a horizontal suture creating a neolabrum can be placed. This technique allows a suitable reinforcement of the capsule without intraoperative complications. In cases of capsular elongation, especially a torn IGHL, the capsular instability can be addressed by the described Sidewinder technique. More sophisticated arthroscopic techniques such as this will increase the indication for arthroscopic shoulder stabilization.

Abstract: PURPOSE: The use of biodegradable implants for arthroscopic repair of meniscal lesions is becoming increasingly popular. The aim of this study was to test the biomechanical stability and the mode of failure of these implants. Type of Study: Biomechanical testing study. METHODS: Biomechanical investigations were performed on human menisci using 6 commonly used biodegradable implants for meniscal repair to compare them with horizontal mattress suture using 2/0 Ethibond (Ethicon, Norderstedt, Germany). Included in this study were the Meniscus Arrow (Bionx, Tampere, Finland), Dart (Arthrex, Naples, FL), Stinger (Linvatec, Largo, FL), Meniscal Screw (Innovasive, Marlborough, MA), T-Fix (Acufex, Mansfield, MA), and the Fastener (Mitek, Westwood, MA). The tests were carried out using a material testing machine at a loading rate of 10 N/second. The ultimate tension load (UTL), elongation, and stiffness were evaluated for each implant technique. RESULTS: The highest UTL was shown by Ethibond (62 +/- 7.91 N) and the T-Fix (51.35 +/- 16.31 N), followed by the Fastener (32.67 +/- 2.97 N). All other implants had a significantly lower UTL (P =.001). Less elongation under a load of 5 N was noted for Ethibond (0.64 +/- 0.25 mm) and for T-Fix (0.43 +/- 0.32 mm) compared with the other implants. The greatest elongation was found for the Fastener (2.239 +/- 0.581 mm). The stiffness of the fixation was similar in all implants, except for the Dart and Fastener, which were significantly inferior (P <.05). CONCLUSIONS: All of the biodegradable implants had lower UTL than the suture techniques. Therefore, when using the implants, they should be inserted close together to provide sufficient stability. In cases of an extended lesion, there might even be an option to combine the implant and suturing techniques.

Abstract: The loss of full muscle activation contributes to weakness of the quadriceps muscle in patients with deficiency of the anterior cruciate ligament (ACL). We examined whether a deficit of voluntary activation (VA) of the quadriceps muscle can be reversed by reconstruction of the ACL and assessed its influence on muscle strength and clinical parameters. We evaluated 12 male subjects with an isolated tear of the ACL and 12 matched control subjects before operation and two years after reconstruction of the ACL. Assessment included measurements of isometric knee-extension torque at maximal voluntary contraction (MVC force), knee stability tests, the International Knee Ligament Standard Evaluation Form and the Tegner activity score. A sensitive method of twitch interpolation was used to quantify the VA and to calculate true muscle force. Before operation we found a deficit of VA on both the injured (mean +/- SEM 74.9 +/- 3.5%) and the uninjured side (74.6 +/- 3.0%) in comparison with the control group (91 +/- 0.9%). Two years after reconstruction of the ACL the VA improved significantly on both sides but remained less than that of the controls. Correlation analysis revealed an improvement of the VA in patients who returned to a higher level of activity. The deficit of true muscle force, however, persisted regardless of the clinical outcome and ligament stability.

Abstract: The aim of our prospective randomised study was to evaluate the clinical results after arthroscopical reconstruction of the ACL using the midthird patellar ligament or semitendinosus tendon. METHODS: Forty patients were followed up two years postoperatively. Twenty of them received either a patellar ligament graft (BTB-group) or doubled semiteninosus tendon (SET-group). The clinical evaluation included the preoperative and two years postoperative assessment, based on the IKDC-Score, Tegener-Score and Mc-Carroll-Score. The a.p.-translation was evaluated using the KT-1000. RESULTS: Sixteen (80%) patients of the SET-group and 10 (50%) patients of the BTB-group showed good and excellent results in the over all assessment with the IKDC-Score. The mean side to side KT-1000 difference yielded 1.6 mm (-2-4 mm) in the BTB-group and 2.7 mm (0-7 mm) in the SET-group (p < 0.05). The retropatellar pain syndrome based on the Mc-Caroll-Score showed 17.4 points in the BTB-group in comparison to 19.5 points in the SET-group (p < 0.05). The level of activity using the Tegner-score showed preoperatively for both the SET- and BTB-group 6.9 points and postoperatively for the SET-group 6.7 points and for the BTB-group 5.6 points. CONCLUSIONS: Despite the inferior a.p.-stability for the patients who received doubled semitendinosus tendon grafts they presented clinically superior results compared to the BTB-group. Therefore this technique seems to be the alternative method. In order to improve the stability we recommend the usage of three or four stranded grafts and an improved fixation technique.

Abstract: Between 1995 and 1997, five patients were operated on with a large osteochondral defect of the femoral condyle using the lateral third of the patella. The age of the four male and one female ranged from 18 to 23 years. Initially all of them suffered from an osteochondrosis dissecans which was located at the typical site on the medial condyle of the femur, in the maximal weight bearing region. The follow-up study was 14 to 35 months and showed an improvement from 35 points preoperatively to 89 points postoperatively based on the Cincinnati knee score. All patients returned to there previous profession as well as mild sports activity. The postoperative examination did not show any retropatellar problems and there were no radiological signs of the femoropatellar joint osteoarthritis. For the operative treatment of large chondral defects at the femoral condyle autologous osteochondral transplantation using the lateral third of the patella seems to be a successful alternative.

Abstract: To investigate whether transcranial magnetic stimulation (TMS) has an effect on isometric muscle force elicited by maximal voluntary contractions (MVC) and the ability to activate a muscle voluntarily (VA, as a percentage of full muscle activation), a twitch-interpolation technique was applied on the quadriceps femoris muscles of six volunteers before and within 1 min after TMS. VA improved by 5% (P = 0.019) and MVC by 17% (P = 0.002), whereas these parameters were unchanged in a control experiment. The results suggest that TMS has an effect on the central motor drive, at least within 1 min after stimulation.

Abstract: The aim of the study was to investigate the ability to activate the quadriceps femoris muscle voluntarily in patients after severe knee injuries and it's influence on muscle function. 33 male patients after ACL-rupture with concomitant injuries were investigated with a twitch-interpolation-method to determine the maximal voluntary contraction force (MVC) and the ability to activate the quadriceps muscle voluntarily. The results were compared to a previously investigated group of patients after isolated ACL-rupture and to an aged-matched control group. The patients with extensive knee injuries presented a significant higher deficit of voluntary quadriceps muscle activation on the injured (78.8 +/- 2.09%, mean +/- SEM) and equally on the uninjured side (78.9 +/- 1.91%) compared to the patients after isolated ACL-rupture and to controls. A minor MVC-deficit of the patients quadriceps muscle of the uninjured side could be explained by the voluntary activation deficit alone, the major MVC deficit of the injured side by muscle atrophy and a voluntary activation deficit. The activation deficit is probably the underlying reason for persisting muscle wasting and [not readable: see text]

Abstract: Short-interval, paired-pulse transcranial magnetic stimulation (TMS) is usually used to demonstrate intracortical inhibition. It was shown recently that with short-interval, paired-pulse TMS a facilitation - called intracortical I-wave facilitation - can also be demonstrated. It was the aim of this study to investigate which stimulus conditions lead to intracortical inhibition and what conditions yield an intracortical I-wave facilitation in a hand muscle of normal subjects. Paired-pulse TMS responses with an interstimulus interval of 1.2 ms were obtained from the abductor digiti minimi muscle of four normal subjects. A threshold-hunting paradigm with hunting through first or second stimulus variation was used to obtain a curve of threshold-pair strengths. All subjects showed two branches of stimulus interaction on this diagram. If the first stimulus of a threshold pair was below approximately 65% of resting motor threshold it modified the response primarily due to the second stimulus through intracortical inhibition. However, if the first stimulus of a threshold pair exceeded approximately 65% of resting motor threshold it became responsible for the spinal action-potential initiation. The subsequent second stimulus served as a "booster" for the ongoing intracortical I-wave activity, making it impossible to observe the intracortical inhibition evoked by the first stimulus.

Abstract: We assessed 35 hip arthroplasties in 30 patients with an average follow-up of 7 years. All patients suffered from secondary osteoarthrosis due to congenital dysplasia. The mean age at the time of surgery was 54 (19-77) years. Part of the femoral head used as a graft was fixed to the superolateral region of the acetabulum. A 100% bone coverage of the acetabular component was achieved initially. The mean support by the graft was 34%. The graft size, measured in the AP view, decreased on average 29% after 7 years. The resorption caused a reduction in cup coverage to 94%. There was no correlation between the clinical outcome and the graft size. Graft resorption occurred in the horizontal and vertical axes, but hardly affected the contact region with the iliac bone. Radiolucent lines according to DeLee were found in zone I in 4, zone II in 6 and zone III in 7 cases. The Harris Hip Score improved from 37-85 points. 1 revision was necessary 7 months postoperatively after cup dislocation.

Abstract: PURPOSE: The inability to fully activate the quadriceps femoris muscle voluntarily is known to accompany several different knee-joint pathologies. The extent of a voluntary-activation deficit in patients after isolated rupture of the anterior cruciate ligament (ACL), however, has been reported to be small or nonexistent, making it questionable if a voluntary-activation deficit is a relevant factor for these patients at all. METHODS: In this study the ability to voluntarily activate the quadriceps femoris muscles was quantified in 22 male patients with arthroscopically-proven isolated ACL ruptures using an established highly sensitive twitch-interpolation technique. Furthermore, the maximal voluntary contraction force of the quadriceps muscle was obtained by isometric knee-joint torque measurements. The results were compared with an age-, gender-, and activity-matched control group. RESULTS: There was a moderate but significant mean reduction in maximal voluntary activation (VA) in both the injured (VA: 83.9 +/- 2.3%, mean +/- SEM) and uninjured side (VA: 84.7 +/- 2.2%) in comparison with controls (VA: 91.1 +/- 0.8%). However, of the patients the 23% who presented a considerably reduced voluntary-activation of less than 80% were mainly responsible for the significant mean deficit. CONCLUSIONS: The deficit of isometric muscle strength on the injured side compared with that of controls was explained by the voluntary-activation deficit and a true muscle weakness. On the other hand, the diminished muscle strength of the uninjured side was explained sufficiently by the voluntary-activation deficit alone. Considering the bilateral voluntary-activation deficit, functional muscle tests might not be valid when the uninjured extremity serves as reference.