[General operative technique of the foot and ankle]. / Allgemeine Operationstechnik an Fuss und Sprunggelenk.

Soft tissue coverage of the foot is more critical than in other orthopedic operation areas. In addition, the foot bears the most mechanical load during walking. Therefore, meticulous operative techniques are of special relevance and tourniquet times must be kept as short as possible. Unnecessary soft tissue dissection must be avoided and electrocautery is not necessary and only damages tissues. Sharp retractors should not be used for the same reason. Osteotomy in three dimensions heals more reliably and inexpensive standard implants can generally be used. Capillary perfusion must be checked following the procedure. A compression dressing avoids postoperative bleeding and swelling. Usually full weight-bearing is possible in a flat postoperative shoe. Postoperative wound coverage must be dry and without ointments or powders.

[Failures of hallux valgus surgery]. / Fehlschläge in der Hallux-Valgus-Chirurgie.

More than 150 corrective procedures for hallux valgus exist and an incorrect choice of procedure leads to insufficient correction. Distal first metatarsal osteotomy cannot correct large deformities and degenerative changes at the metatarsophalangeal joint impede functional recovery. Incongruence of the joint must be corrected during surgery. Recurrence is most often caused by insufficient correction, especially of the first metatarsal bone. Overcorrection is often due to technical problems with the initial metatarsal osteotomy. This also applies to insufficiency of the first ray due to shortening or dorsal angulation. Partial first metatarsal head necrosis occasionally occurs but complete necrosis is rare. Non-union is mostly caused by incorrect osteosynthesis. During postoperative treatment the hallux must be held in the correct position to avoid failure.

[Recurrent hammer and clawed toes after surgical correction]. / Rezidive nach Korrektur von Hammer- und Krallenzehen.

Symptomatic lesser toe deformities should be corrected if conservative therapy is exhausted or no longer seems appropriate. Prevention of recurrence starts with the correct indication for the appropriate surgical procedure. The occasional difficult question of the cause of the deformity is crucial in this context. A correct surgical technique and appropriate after-care reduces the risk of recurrence. Due to tensed bony and soft-tissue conditions, revision surgery of the forefoot is challenging. If a revision becomes necessary, the cause of recurrence must be re-examined. This paper explains the appropriate indications and surgical techniques for correction of lesser toe deformities. Subsequently, specific postoperative complications and their management are discussed in detail.

[Problem cases of metatarsalgia]. / Problemfälle bei Metatarsalgie.

Metatarsalgia is characterized by pain under the metatarsal heads and is a very common cause of foot pain among adults. Symptoms can be isolated or in combination with accompanying deformities occurring in the forefoot and/or hindfoot. In the foreground of the treatment is the exhaustion of conservative forms of therapy to minimize the symptoms of local pressure increase and callus under the metatarsal heads. In addition, various surgical methods are available, such as corrective osteotomy of the metatarsal bone, soft tissue interventions and the correction of associated deformities. The indications for surgical intervention should be made with caution in order to avoid failures and complaints persisting after surgery. The most common problems are an inadequate indication for surgery, technical problems and insufficient postoperative treatment.

Chopart's joint load during gait. In vitro study of 10 cadaver specimen in a dynamic model.

BACKGROUND: Chopart's joint is fundamental to foot function. Until today, intra-articular force and peak pressure has not been investigated under dynamic conditions. METHODS: The study used a cadaver model to measure intra-articular force and peak pressure with electronic sensors. Force was applied to extrinsic tendons via cables attached to computer-regulated hydraulic cylinders. A ground reaction force of 350 N was simulated in a tilting angle- and force-controlled translation stage. RESULTS: We observed a characteristic rising curve with a peak during push-off for intra-articular force and peak pressure. The increase of intra-articular force at the talonavicular and calcaneocuboid joint from a low level at heel-on varies up to a maximum of 174 N/149 N and a peak pressure of 3877 kPa/3396 kPa, respectively, at push-off. We observed highest loading at the dorsal aspect of the talonavicular joint and the plantar aspect of calcaneocuboid joint. CONCLUSION: The highest loading on Chopart's joint is attained during push-off. We observe higher force and peak pressure on the medial column of the foot compared to the lateral column. The higher load of the dorsal aspect of talonavicular joint and plantar aspect of calcaneocuboid joint confirms the theory of a previous described locking mechanism for forceful push-off.

Changes in Chopart joint load following tibiotalar arthrodesis: in vitro analysis of 8 cadaver specimens in a dynamic model.

BACKGROUND: In the current discussion of surgical treatment of arthroses in the ankle joint, arthrodesis is in competition with artificial joint replacement. Up until now, no valid biomechanical findings have existed on the changes in intraarticular loads following arthrodesis. One argument against tibiotalar arthrodesis is the frequently associated, long-term degeneration of the talonavicular joint, which can be attributed to changes in biomechanical stresses. METHODS: We used a dynamic model to determine the changes in intraarticular forces and peak-pressure in the talonavicular joint and in the calcaneocuboid joint on 8 cadaver feet under stress in a simulated stance phase following tibiotalar arthrodesis. RESULTS: The change seen after arthrodesis was a tendency of relocation of average force and maximum pressure from the lateral onto the medial column of the foot. The average force increased from native 92 N to 100 N upon arthrodesis in the talonavicular joint and decreased in the calcaneocuboid joint from 54 N to 48 N. The peak pressure increased from native 3.9 MPa to 4.4 MPa in the talonavicular joint and in the calcaneocuboid joint from 3.3 MPa to 3.4 MPa. The increase of force and peak pressure on the talonavicular joint and decrease of force on the calcaneocuboid joint is statistically significant. CONCLUSION: The increase in imparted force and peak pressure on the medial column of the foot following tibiotalar arthrodesis, as was demonstrated in a dynamic model, biomechanically explains the clinically observed phenomenon of cartilage degeneration on the medial dorsum of the foot in the long term. As a clinical conclusion from the measurements, it would be desirable to reduce the force imparted on the medial column with displacement onto the lateral forefoot, say by suitable shoe adjustment, in order to achieve a more favourable long-term clinical result.

[Pigmented villonodular synovitis]. / Seltene Schleimhauterkrankung zerstört die Gelenke. Frühzeitige Diagnose erspart Gelenkersatz.

Pigmented villonodular synovitis (PVNS) is a rare, strongly proliferative disease of the lining of thejoint, synovial bursa and tendon (synovial) sheath. If left untreated, it leads to severe destruction of the joint resulting in an early need for endoprosthetic replacement. The clinical signs are unspecific. Using the diagnostic gold standard MRI, the complete extent of PVNS can usually be determined non-invasively. Once histological confirmation has been obtained, radical tumor resection, synovectomy, possibly curettage, and postoperative irradiation must be applied.

Medially based anterior capsular shift of the glenohumeral joint. Passive range of motion and posterior capsular strain.

The effect of a medially based anterior capsular shift on translational and rotational range of motion and posterior capsular strain was investigated in an in vitro model. Six cadaveric shoulders were tested in a robot-assisted shoulder simulator. Translational and rotational range of motion were reduced by the capsular shift, particularly with the shoulder at higher elevation angles. At 60 degrees of elevation, anterior translation was decreased 1.9 +/- 2.9 mm, and posterior translation was decreased 2.3 +/- 6.2 mm. External rotation was decreased 11.5 degrees +/- 10.2 degrees, and internal rotation was decreased 8.9 degrees + 5.7 degrees. Posterior capsular strain change was dependent on elevation angle. At 30 degrees of elevation, strain tended to increase 5.0% +/- 7.3% in the inferior aspect and 2.9% +/- 2.6% in the superior aspect, with no change detected in the medial aspect. At 60 degrees of elevation, strain increased 6.6% +/- 8.0%, 3.2% +/- 2.6%, and 4.4% +/- 3.5% in the inferior, middle, and superior aspects, respectively. Our results support the use of the medially based anterior shift for shoulders with anterior-inferior instability or multidirectional instability with posterior involvement.

Reconstruction of the lateral ligaments of the ankle using a regional periosteal flap.

We have treated 94 patients with chronic instability of the lateral side of the ankle by reconstruction of the ligaments with local periosteal tissue. We reviewed 90 cases after a mean follow-up of 2.8 years (2 to 9) using a questionnaire, clinical examination and radiography. The results on a 100-point ankle score indicated that 81% had a good or excellent result. The periosteal flap-replacement technique allows anatomical reconstruction and does not sacrifice other ligaments or tendons in the foot.

Medial meniscus replacement by a tendon autograft. Experiments in sheep.

In 20 skeletally mature female merino sheep, divided into four groups, we performed total medial meniscectomy, removal of the middle third of the patellar tendon, and tenotomy of the calcaneal tendon of the right hind leg. Group I (control) had no additional procedures. In the other three groups the medial meniscus was replaced by the middle third of the patellar tendon from the ipsilateral knee. The animals were killed at three (group II), six (group III), or 12 months (group IV) and the tendon-meniscus examined macroscopically, by light and scanning electron microscopy, and biomechanically. Remodelling of the tissue had taken place by 12 months but the failure stress and tensile modulus for the tendon-meniscus were lower than for the normal meniscus. Our evidence suggests that, in sheep, replacement of a meniscus by a tendon autograft may decrease the severity of the degenerative changes that occur after meniscectomy.

The effect of negative intraarticular pressure and rotator cuff force on glenohumeral translation during simulated active elevation.

OBJECTIVE: The objective of this study was to determine the effect of negative pressure in the intraarticular space and subacromial bursa, as well as rotator cuff force, on glenohumeral translation during active elevation. DESIGN: Glenohumeral translation during elevation in the scapular plane was measured under greater than, less than, and equal to physiologic rotator cuff muscle force, as well as with and without the subacromial bursa and intraarticular space vented. BACKGROUND: Negative intraarticular pressure has been shown to help stabilize the glenohumeral joint in passive motion, although the effect on translation during active motion has not been investigated. METHODS: Eight cadaverous human shoulder specimens were tested in a dynamic shoulder simulator. Forces in the muscles of the rotator as well as the middle deltoid muscle were simulated using servohydraulic cylinders. Joint motion was measured using an ultrasonic motion analysis system. RESULTS: Superior translation of the humerus increased 1.2 mm (SD, 0.4) upon venting of the bursa, and 2.1 mm (SD, 1.7) upon venting of the joint capsule at 25 degrees of glenohumeral elevation in the scapular plane. At 90 degrees elevation, venting the bursa did not change superior translation but increased anterior translation 1.04 mm (SD, 1.0). Venting of the joint capsule increased superior translation by 2.8 mm (SD, 2.5). Decreasing rotator cuff force increased superior translation, while reducing it did not. CONCLUSION: The muscles of the rotator cuff and the negative pressure of the intraarticular space and the subacromial bursa stabilize the glenohumeral joint since they restrict translation in the superior and anterior directions. RelevanceIncreased glenohumeral translation and the resulting asymmetric loading may lead to arthrosis and ultimately rotator cuff arthropathy.

Hindfoot motion after isolated and combined arthrodeses: measurements in anatomic specimens.

Passive motions at the subtalar joint, talonavicular joint and calcaneocuboid joint were measured in eight ankle specimens, using an ultrasonic motion analysis system. Arthrodeses of the three joints were performed in all feasible combinations and the resulting motion change at the unfused joints was determined. Motion at the subtalar joint was not significantly affected by fusion of the calcaneocuboid joint, reduced to one quarter by fusion of the talonavicular and calcaneocuboid joints (double arthrodesis) and almost completely eliminated with all other fusions. Motion at the talonavicular joint was not significantly affected by calcaneocuboid fusion and reduced to approximately one third with the subtalar and the double arthrodesis. Motion at the calcaneocuboid joint was not significantly reduced by subtalar fusion but almost completely eliminated in all fusions involving the talonavicular joint. It is concluded that the talonavicular joint is the key articulation for hindfoot motion. Double arthrodesis preserved significant motion at the subtalar joint. Fusion of the calcaneocuboid joint had no significant influence on remaining hindfoot motion.

Treatment of lateral ankle ligament tears. Operative or conservative?

In lateral ankle ligament tears, the anterior talofibular ligament ruptures most commonly, often in conjunction with the calcaneofibular ligament. The posterior talofibular ligament is rarely affected. Associated injuries at the adjacent ligamentous structures or at the articular cartilage of the ankle commonly occur. The diagnosis is established clinically with the anterolateral drawer sign and an increased lateral talar tilt. Stress radiographs in two planes demonstrate talar tilt and anterior displacement of the talus, in comparison to the unaffected side. Magnetic resonance imaging provides an early diagnosis of concomitant injuries. Simple, acute lateral ankle ligament tears are treated non-operatively. Surgery is indicated in dislocated bone avulsions and in chondral or osteochondral fractures. A recurrent tear in an athletic patient should also be treated operatively. Athletic endeavours, the number of torn ligaments and patient age are no useful indicators for surgical treatment. Conservative treatment consist of oedema therapy, immobilization of the fibular ligaments with as little compromise of ankle joint function as possible, and rehabilitation with muscle strengthening and proprioception training. During surgery, the ligament stumps are reapproximated in anatomic position, reinforced with local tissue if necessary, and the articular surface is examined for concomitant injuries.

Omarthrose.

Degenerative arthrosis of the shoulder is less commonly||| diagnosed than at the joints of the lower extremity. The shoulder joint does||| not bear weight and some of the mechanical stresses are taken up by the||| subacromial space. However, anatomical studies reveal a significant incidence||| of degenerative changes at the glenohumeral joint with increasing age.||| Arthrosis is caused by mechanical loading, rotator cuff defects, and abnormal||| joint motion following surgery. Clinical symptoms are rarely focused on the||| glenohumeral joint. Clinical findings are also unspecific. Rotation of the||| elevated arm with compression of the joint is a reliable sign of arthrosis. The||| diagnosis is made with anteroposterior and axial radiographs. Ultrasonography||| should always be performed and computed tomography only in specific cases.||| Nonoperative treatment includes analgesic and antiphlogistic medication, motion||| therapy, and muscle exercises. Shoulder arthroplasty is favoured in advanced||| arthrosis. New prostheses are intended to reconstruct the normal anatomy as||| closely as possible.

[Influence of the posterior tibial tendon on the medial arch of the foot: an in vitro kinetic and kinematic study]. / Einfluss der Tibialis-posterior-Sehne auf die Fusslängswölbung: eine In-vitro-kinetische und kinematische Untersuchung.

INTRODUCTION: The respective contributions of the active and passive structures of the foot to the stability of the medical arch were investigated using an in vitro kinetic and kinematic model. The effect of the tibialis posterior tendon on foot and ankle movements, and plantar pressure distribution of the foot were tested in a cadaveric human foot. METHOD: The stance phase from heel-contact to toe-off of normal walking gait and after tibialis posterior tendon rupture was simulated in eight roentenographically normal human feet (age 66 +/- 19 years, males). Ground reaction force and tibial inclination was simulated by means of a tilting angle and force-controlled translation stage. Plantar pressure was measured using a pressure-measuring platform. The force developed by the flexors and extensor muscles of the foot were simulated via cables attached to 7 force-controlled hydraulic cylinders. Tibial rotation was produced by an electric servo-motor, and foot movements measured with an ultrasonic analysis system. RESULTS: The model was verified against the plantar distribution and kinematics of healthy subjects measured during normal gait. Tibialis posterior deficit did not result in any detectable changes in pressure or force-time integral in the medial regions of the foot--a common sign of flat foot (pressure: midfoot 0.2 < or = 0.9; medial forefoot 0.5 < or = p < or = 0.9; hallux 0.5 < or = p < or = 0.9; force-time integral: midfoot p = 0-871; medial forefoot p = 0.632; hallux p = 0.068). Only small tendential changes in the kinematics of the talus and calcaneus were observed in dorsiflexion (0-58 sec; talus 0.1 < or = p < or = 0.6; calcaneus 0.4 < or = p < or = 0.06) and eversion (talus: 0-60 sec. 0.1 < or = p < or = 0.6; calcaneus: 37-60 sec. 0.2 < or = p < or = 0.7). CONCLUSION: The results of this in vitro study show that defective tibialis posterior alone does not produce significant changes in the kinetics or kinematics of the stance phase of normal gait. This suggests that the development of flat foot observed in degeneration of the tibialis posterior tendon occurs only after fatigue of the passive structures of the foot.

[Muscle efficiency in total shoulder prosthesis implantation: dependence on position of the humeral head and rotator cuff function]. / Muskeleffizienz bei totaler Schulterendoprothetik: Abhängigkeit von Kalottenposition und Rotatorenmanschettenfunktion.

Modern shoulder prostheses permit an anatomic reconstruction of the joint, although the biomechanical advantages are not proven. The goal of this study was to investigate the relationship between position of the humeral head and function of the shoulder prosthesis (muscle efficiency). Shoulder elevation-motion and rotator cuff defects were simulated in vitro in a robot-assisted shoulder simulator. The EPOCA Custom Offset shoulder prosthesis (Argomedical AG, Cham, CH) was implanted in seven normal shoulders (77 +/- 20 kg, 55 +/- 14 years). Active elevation was simulated by hydraulic cylinders, and scapulothoratic motion by a specially programmed industrial robot. Muscle efficiency (elevation-angle/muscle-force of the deltoid muscle) was measured in anatomic (ANA), medialised (MED) and lateralised (LAT) positions of the humeral head, with or without rotator cuff muscle deficiency. Medialisation increased efficiency by 0.03 +/- 0.04 deg/N (p = 0.022), lateralisation decreased it by 0.04 +/- 0.06 deg/N (p = 0.009). Supraspinatus muscle deficiency increased the deltoid force required to elevate the arm, and thus decreased efficiency (ANA p = 0.091, MED p = 0.018, LAT p = 0.028). The data confirm that the position of the humeral head affects the mechanics of total shoulder arthroplasty. Medialisation increases efficiency of the deltoid muscle and may prove useful in compensating isolated supraspinatus muscle deficiency. Lateralisation, in contrast, leads to an unfavorable situation.

[The value of dynamic examination methods in instability of the shoulder joint]. / Die Wertigkeit dynamischer Untersuchungsmethoden bei der Instabilität des Schultergelenks.

We prospectively examined 25 patients with shoulder instability by clinical examination and by fluoroscopic and sonographic imaging. 14 patients were classified as recurrent, posttraumatic instabilities, 12 of these anterior and two posterior. Clinical examination revealed the direction of instability in 5 patients, fluoroscopy in 5 and sonography in 3 patients. 11 patients had non-traumatic recurrent instabilities. Of these, clinical examination and fluoroscopy demonstrated identical directions of laxity in 8. Sonography concurred with the other techniques in only three cases. We recommend manual instability testing followed by fluoroscopy for evaluation and documentation of patients with non-traumatic, recurrent shoulder instability. Posttraumatic instabilities should be diagnosed with other, static procedures.

[Dynamic stability of the glenohumeral joint. A biomechanical study]. / Die dynamische Stabilität des Glenohumeralgelenks. Eine biomechanische Untersuchung.

Stability of the glenohumeral joint with an anterior, posterior and inferior displacement force of 50 Newton was measured in a dynamic shoulder model. Controlled hydrodynamic actuator forces were applied to the deltoid muscle and to the rotator cuff in seven anatomic specimens. During elevation of the arm, the position of the humerus was measured with a six-degree-of-freedom ultrasonic sensor device. The rotational center of the humeral head was used as reference point for translation. A displacement force of 50N led to significant humeral head displacement anteriorly and posteriorly, but not inferiorly. A 50% reduction of rotator cuff forces increased anterior displacement by 46% and posterior displacement by 31%. Venting of the glenohumeral joint space and of the subacromial bursa resulted in a 50% increase of anterior displacement, a 19% increase of posterior displacement and in significant inferior displacement. This study demonstrates that, in addition to passive stabilizers and negative intraarticular pressure, rotator cuff force significantly contributes to stabilization of the glenohumeral joint during arm motion. Muscle strength and coordination should gain more emphasis in the diagnosis and treatment of shoulder instability.

[The significance of the activity score in evaluating knee ligament reconstructions]. / Die Bedeutung des Aktivitäts-Scores bei der Bewertung von Kniebandrekonstruktionen.

In a follow-up study of 156 patients after knee ligament reconstruction for chronic instability, the results of subjective Lysholm score grading and of Tegner activity grading were compared. The postoperative Lysholm score averaged 85 +/- 13.2 points, the activity scores 6.9 +/- 0.9 points prior to instability, 1.7 +/- 0.9 points preoperatively and 5.9 +/- 1.2 points postoperatively. 89 patients reached their preinjury activity level, the average improvement through surgery was 4.2 +/- 1.6 points. Non-active patients regularly returned to their original activity-level, competitive athletes were less likely to regain their previous activity. The subjective results of athletes and non-athletes showed no significant differences. The postoperative activity level clearly correlated to subjective grading by the patient. For scoring results after knee ligament surgery, we use the subjective Lysholm score and an activity score based on average German sports activities.