Survivorship, complications and patient-reported outcomes in calcar-guided short-stem THA: prospective mid-term multicenter data of the first 879 hips

INTRODUCTION

Short stems are a bone and soft-tissue preserving alternative to conventional stems. The aim of this multicenter study is to present the mid-term outcomes of a calcar-guided short stem.

MATERIALS AND METHODS

This is a prospective case series of the first 879 total hip arthroplasties performed on 782 patients across 5 centers using identical calcar-guided short stems. In a mid-term follow-up (6 years), rates and reasons for complications and revisions were documented. The Harris Hip Score (HHS) was obtained; patients reported pain and satisfaction using a visual analog scale.

RESULTS

A total of 43 patients died in the study cohort for non-related reasons; 26 patients (3.0%) required at least 1 revision after the index procedure. The survival rate for endpoint stem revision at mid-term was 98.4%. The main reasons for stem revision were aseptic loosening and early periprosthetic fractures. Sex had no influence on stem survival. Older patients or those with a high body mass index showed increased risk for stem revision during follow-up. Dorr type A morphology revealed a significantly lower risk of stem revision than Dorr type B or C (p = 0.0465). The HHS, satisfaction, and load pain at mid-term were 96.5 (SD 8.0), 9.7 (SD 0.9), and 0.5 (SD 1.9), respectively.

CONCLUSIONS

This short stem produced highly satisfactory outcomes at mid-term, with 98.4% implant survival for any cause of stem revision and low complication rates. Long-term results are required to further evaluate these promising mid-term results.

Assessment of pelvic tilt in anteroposterior radiographs by means of tilt ratios

INTRODUCTION

In anteposterior (AP) radiographs, cup position in total hip arthroplasty and acetabular anatomy in hip-preserving surgery are highly influenced by pelvic tilt. The sagittal rotation of the anterior pelvic plane is an important measurement of pelvic tilt during hip surgery. Thus, correct evaluation of cup position and acetabular parameters requires the assessment of pelvic tilt in AP radiographs.

METHODS

Changes in pelvic tilt inversely change the height of the lesser pelvis and the obturator foramen in AP radiographs. Tilt ratios were calculated by means of these two parameters in simulated radiographs for ten male and ten female pelvises in defined tilt positions. A tilt formula obtained by exponential regression analysis was evaluated by two blinded investigators by means of 14 simulated AP radiographs of the pelvis with pelvic tilts ranging from + 15° to - 15°.

RESULTS

No differences were found between male and female tilt ratios for each 5° step of simulated pelvic tilt. Pelvic tilt and tilt ratios correlated exponentially. Using the tilt formula, the two blinded investigators were able to assess pelvic tilt with high conformity, a mean relative error of + 0.4° (SD ± 4.6°), and a mean absolute error of 3.9° (SD ± 2.3°). Neutral pelvic tilt is indicated by a tilt ratio of 0.5 when the height of the lesser pelvis is twice the height of the obturator foramen.

CONCLUSION

The analysis and interpretation of cup position and acetabular parameters may be improved by our method for assessing pelvic tilt in AP radiographs.

[Examination of the wrist and hand]

The wrist and hand form a highly complex organ that is of great importance in almost all daily activities. The hand serves as a tool and an organ of sense. Injuries of the hand and wrist as well as mechanical, neurological or systemic inflammatory changes are common. Taking a detailed history can already lead to a diagnosis. Almost all structures of the hand are easily accessible for clinical examination, i. e. inspection, palpation and clinical tests, including dynamic testing. Diagnostic imaging completes the examination procedure.

[Examination of the wrist and hand]

The wrist and hand form a highly complex organ that is of great importance in almost all daily activities. The hand serves as a tool and an organ of sense. Injuries of the hand and wrist as well as mechanical, neurological or systemic inflammatory changes are common. Taking a detailed history can already lead to a diagnosis. Almost all structures of the hand are easily accessible for clinical examination, i. e. inspection, palpation and clinical tests, including dynamic testing. Diagnostic imaging completes the examination procedure.

[Operative therapy for rheumatoid arthritis of the hand]

The need for operative treatment of severe rheumatic deformities of the hand and wrist is decreasing due to the increased use of disease-modifying drugs; however, some patients do not tolerate or do not sufficiently respond to these drugs, which often results in the hands being affected and in advanced stages to severe deformity and loss of function. In these cases operative surgery can help to slow the progression of rheumatic destruction and restore the function of the patient's hand. This article describes the principles of surgery for rheumatoid arthritis of the hand. A meticulous synovectomy or tenosynovectomy is the first stage of treatment. With progression of rheumatic destruction various salvage procedures are necessary to preserve the best possible functional state.

[Operative treatment of the rheumatic shoulder]

The duration and severity of rheumatic diseases of the shoulder correlate with symptom frequency, structural changes and associated functional limitations. The multifactorial character of the underlying rheumatic disease requires a multimodal therapeutic concept including interaction of surgical and non-surgical disciplines. In addition to basic systemic anti-inflammatory medication, injections targeting the synovial tissue by corticoid instillation and glenohumeral radiosynoviorthesis (with an intact rotator cuff) are further options. Operative interventions on rheumatic shoulders can be characterized as disease-modifying, protective, reconstructive or palliative, depending on the stage. Combining minimally invasive arthroscopic surgical techniques with modern basic therapy has the potential to shift the indications for operative interventions towards an earlier stage of disease without favoring or propagating structural alterations which have already occurred. In cases of severe joint destruction with loss of the rotator cuff, reverse shoulder arthroplasty can be an appropriate option.

Current therapeutic strategies of heterotopic ossification--a survey amongst orthopaedic and trauma departments in Germany

Background

Heterotopic ossification (HO) is a complication after tissue trauma, fracture and surgery (i.e. total hip arthroplasty). Prophylaxis is the most effective therapy. If HO formations become symptomatic and limit patients’ quality of life, revision surgery is indicated and is usually combined with a perioperative oral prophylaxis (NSAIDs) and/or irradiation. However, a long-term use of NSAIDs can induce gastro-intestinal or cardiac side-effects and possible bony non-unions during fracture healing. Subject of this study was to assess the current status of HO prophylaxis after injuries or fractures and to evaluate current indications and strategies for excision of symptomatic HO.

Methods

Between 2013 and 2014, a questionnaire was sent to 119 orthopaedic and trauma surgery departments in Germany. Participation was voluntary and all acquired data was given anonymously.

Results

The cumulative feedback rate was 71 %. Trauma and orthopaedic surgery departments in Germany recommend oral HO prophylaxis after acetabulum and femoral neck fractures, elbow dislocation, and fracture or dislocation of the radial head. Pain upon movement and an increasing loss of range of motion in the affected joint are considered to be clear indications for HO surgery. A partial removal of ROM-limiting HO formations was also considered important. The vast majority of all departments include perioperative oral HO prophylaxis and/or irradiation if surgical HO removal is planned. The choice and duration of NSAIDs is highly variable.

Conclusion

HO is of clinical significance in current traumatology and orthopaedics. Certain fractures and injuries are prone to HO, and prophylactic measures should be taken. The respondents in this survey assessed current therapeutic strategies for HO formations similarly. These concepts are in line with the literature. However, the duration of perioperative oral HO prophylaxis varied greatly among the specialist centres. This is significant as a long-term use of NSAIDs fosters a potential risk for the patients’ safety and could influence the clinical outcome. National and international guidelines need to be developed to further reduce HO rates and improve patients’ safety in trauma and orthopaedic surgery.

[Wrist arthroscopy : challenging procedure of modern hand surgery]

Arthroscopy of the wrist has developed in the shadow of arthroscopy of the large joints. Nowadays, wrist arthroscopy has a relevant importance in the diagnostics and therapy in hand surgery and is indispensable for serious surgery of the wrist. Special equipment and extensive knowledge of the surgeon are necessary for carrying out the procedure.

Proximal interphalangeal joint replacement with an unconstrained pyrocarbon prosthesis (Ascension(R)): a long-term follow-up

There have been limited publications that report long-term outcomes of pyrocarbon implants. This report describes both clinical and radiographic long-term results for patients who have been treated with pyrocarbon proximal interphalangeal implants. Thirteen implants in ten patients are reported for an average follow-up of 8.3 years (range 6.2-9.3). All patients were suffering from degenerative joint disease. Five of the 13 digits were free of pain, the remaining eight digits had mild to moderate pain (visual analogue scale 2-5). The average active range of motion was 58° (SD 19°) at latest examination. X-ray results were unremarkable in six digits with an acceptable position of the prosthesis. However, in seven patients significant radiolucent lines (≥ 1 mm) were observed. Three prostheses demonstrated a migration of the proximal component, and one a subsidence of the distal component. Our study does not support the use of this implant for treatment of osteoarthritis of the finger joint owing to high complication rates and limited range of motion.

Gait analysis after tibialis anterior tendon rupture repair using Z-plasty

Other than limited reports regarding surgical outcomes, little information is available regarding whether Z-plasty of the tibialis anterior results in normal gait kinematics. We included 5 patients with spontaneous ruptures in the present retrospective study. The mean interval between rupture and operative treatment was 2.6 ± 2.6 months (standard deviation). The mean age of the patients was 63 (range 40 to 80) years. All patients were treated operatively with Z-plasty. Gait analysis was used to study the outcome, comparing the operated and nonoperated limbs. The patients were tested after a mean follow-up of 22 (range 12 to 33) months. No repeat ruptures were noted. Plantarflexion was significantly diminished during the preswing phase and initial swing phase in the operated limbs compared with the uninjured limbs. Plantarflexion was significantly increased during the terminal swing phase on the operated side. Knee flexion was nearly symmetrical. No significant differences regarding the temporospatial parameters were noted. We recommend Z-plasty for ruptures of the tibialis anterior tendon as a safe and effective procedure. However, this technique does not fully restore a physiologic gait pattern.

[The role of hyperlaxity in open stabilisation of post-traumatic shoulder instability]

BACKGROUND

Chronic post-traumatic shoulder instabilities as well as post-traumatic shoulder instabilities in association with joint laxity are accepted reasons for open capsular shift and labral refixation. However, it remains unclear whether hyperlaxity influences clinical outcome and reluxation rates.

MATERIAL AND METHOD

A total of 60 patients (48 men and 12 women) with diagnosed post-traumatic anterior glenohumeral instability were included in the study. Average follow-up was 3.6 ± 0.2 years (median 3.1 years, minimum 2 years, maximum 8 years). 37 patients (61 %) had a joint hyperlaxity grade II or more. In 77 % of the cases glenoid osseus defects were observed (< 20 % of the glenoid fossa).

RESULTS

Three cases of shoulder dislocations (5 %) recurred after surgery, following a massive trauma during sports activities. One patient was excluded from the study due to other reasons. The average Rowe scores were 88.7 points. No significant differences were observed between patients with and without concomitant hyperlaxity. From 56 patients without postoperative redislocations 55.2 % had a very good, 34 % a good, and 10.3 % a satisfactory result (Rowe score). The relative constant score and force measurement values were significantly lower in hyperlax shoulders. The average loss of external rotation was 3.9 degrees with the arm at the side and 11 degrees with the arm in 90 degrees of abduction.

CONCLUSION

Our study shows that hyperlaxity does not lead to a higher redislocation rate following open anatomic refixation of the capsule-labrum complex in combination with a capsular shift.

Development and evaluation of an image-free computer-assisted impingement detection technique for total hip arthroplasty

Periprosthetic or bony impingement in total hip arthroplasty (THA) has been correlated to dislocation, increased wear, reduced postoperative functionality with pain and/or decreased range of motion (ROM). We sought to study the accuracy and assess the reliability of measuring bony and periprosthetic impingement on a virtual bone model prior to the implantation of the acetabular cup with the help of image-free navigation technology in an experimental cadaver study. Impingement-free ROM measurements were recorded during minimally invasive, computer-assisted THA on 14 hips of 7 cadaveric donors. Preoperatively and postoperatively the donors were scanned using computed tomography (CT). Impingement-free ROM on three-dimensional CT-based models was then compared with corresponding, intraoperative navigation models. Bony/periprosthetic impingement can be detected with a mean accuracy limit of below 5° for motion angles, which should be reached after THA for activities of daily living with the help of image-free navigation technology.

Mittelfristige Ergebnisse nach Implantation einer Pyrocarbonprothese bei Fingermittelgelenksarthrose

Ziel: Evaluation mittelfristiger klinischer und radiologischer Ergebnisse der ungekoppelten Pyrocarbonprothese (Ascension®) in der Behandlung der schmerzhaften idiopathischen Arthrose des Fingermittelgelenks. Methode: In dieser Studie konnten 13 implantierte Prothesen (10 Patienten) nach durchschnittlich 71 Monaten retrospektiv klinisch und radiologisch analysiert werden. Ergebnisse: Das durchschnittliche postoperative Bewegungsausmaß lag bei 52° (± 27° STD). Eine Luxation der Komponenten wurde bislang nicht beobachtet. Auch ein Ausbau einer Prothese war bisher nicht erforderlich. Eine radiologisch signifikante periprothetische Lysezone (≥ 1 mm) wurde bei 7 Prothesen beobachtet. In 3 Fällen kam es dabei zu einer Wanderung der Komponenten und in 1 Fall zu einer Lockerung der Prothese mit Drehung der proximalen Komponente um die Längsachse. Radiologisch unauffällig waren nur 6 Prothesen mit regulärer Stellung der Komponenten. Schlussfolgerung: Nach durchschnittlich 6 Jahren postoperativ besteht eine hohe Komplikationsrate mit einer eingeschränkten Beweglichkeit. Bei anzunehmender fehlender Osteointegration bestehen bei der Hälfte der Patienten radiologische Veränderungen. Das postoperative Bewegungsausmaß zeigt eine hohe Varianz, was bei der Patientenaufklärung berücksichtigt werden muss.

[Littler tenodesis for correction of swan neck deformity in rheumatoid arthritis]

PURPOSE

The aim of this study was to assess the results of operative treatment for rheumatoid swan neck deformity using Littler's technique consisting in the reconstruction of the oblique retinacular ligament.

PATIENTS AND METHOD

From 2004 to 2007 twenty rheumatoid patients with 30 PIP-joints affected by swan neck deformity underwent surgical correction. In all cases the tenodesis described by Littler was used. Modification of the operative procedure because of insufficiency of the Cleland ligament or the A2-pulley was in no case necessary. Twenty six PIP-joints in 17 patients could be examined after an average follow-up of 22 months. In two PIP-joints the deformity was contract and in 12 PIP-joints partially contract. In 10 joints a dorsal arthrolysis had to be performed and in one a lengthening of the central slip. All PIP-joints were transfixed in 30 degrees flexion. After 6 weeks the transfixing wire was removed and active PIP- joint mobilisation was allowed. Active extension was limited to 20 degrees of flexion until the end of the 12 (th) postoperative week. During this time an extension blocking splint was used. After the 12 (th) week free active and passive mobilisation of the PIP-joint was allowed. In a retrospective study pre- and postoperative range of motion, X-ray findings, pain and patient's content were examined.

RESULTS

Swan neck deformity was corrected in all cases. Preoperative hyperextension of 21 degrees on average was corrected to 24 degrees of flexion. Thereby the ROM of 48 degrees was shifted from the extension sector to a ROM of 51 degrees towards the flexion sector. Recurrence of the deformity or complications were not noted. Pain could be reduced except in one patient. Radiologic changes were classified Larsen grade 2.2 before and 2.3 after operation.

CONCLUSION

With the oblique retinacular ligament repair described by Littler reliable results can be achieved in rheumatoid swan neck deformity. It is indicated in contract and non-contract rheumatoid swan neck deformity when th PIP-joints are radiologically in a stage of less than Larsen grade 3. It corrects the deformity at the level of the PIP-joint as well as the DIP-joint.

[Examination of the painful wrist]

The anatomy of the wrist is complex. Mechanical, neurological or systemic causes are responsible for a painful wrist. In many cases a specific diagnosis can already be made by taking a precise medical history. Physical examination includes inspection, palpation of landmarks and a dynamic examination in regard to joint regions. Plane X-Ray examinations are the basic tools in diagnostic imaging. Additional radiographic adjustments, ultrasound-, MRI- and CT-examinations may lead to more detailed information in special cases. A diagnostic arthroscopy is accomplished, if a pathological cause for wrist-pain with non-invasive methods cannot be found.

[Imaging in evaluating rotator cuff tears]

Diagnostic imaging in a patient with shoulder pain should be used only after a comprehensive clinical evaluation of the shoulder. X-ray and ultrasonography are the basic diagnostic tools; computed tomography and magnetic resonance imaging (MRI) should be used only with certain indications. Ultrasonography and MRI have comparable accuracy for identifying and measuring full-thickness rotator cuff tears, but the accuracy for identifying partial-thickness still needs to be improved. MR arthrography has significantly improved sensitivity and specificity for partial-thickness tears of the cuff. Only ultrasound provides a real-time examination tool during shoulder movements. Moreover, dynamic ultrasonography can assess the contraction patterns of the supraspinatus and infraspinatus muscles, which may improve decision making in the treatment of shoulder diseases. In depicting fatty atrophy of the supraspinatus and infraspinatus muscles, MRI remains the reference standard. MRI should not be used as a diagnostic screening tool in patients with chronic shoulder pain because it does not appear to significantly affect treatment or outcome.

[Nonoperative management of rotator cuff defects]

Rotator cuff defects are common disorders of the shoulder. Although the outcome of surgical treatment of rotator cuff tears is well documented in the literature, less is known about the efficacy of physical therapy for symptomatic rotator cuff tears. Clear therapeutic standards are still missing. This article presents the nonoperative treatment options as well as a literature review. The results of most studies show that patients with rotator cuff defects do benefit from both physical therapy and simple home exercises independent from the size of the defect. However, due to the heterogeneity of outcome measures used, it is difficult to compare the results published. There is still a need for well-planned randomised controlled studies investigating the efficacy of exercise in the management of rotator cuff tears.

MR imaging of the intraarticular disk of the acromioclavicular joint: a comparison with anatomical, histological and in-vivo findings

OBJECTIVE

To characterize MRI features of the intraarticular disk of the acromioclavicular joint.

DESIGN

We studied the appearance of 11 acromioclavicular joints of six cadavers (subjects aged 57-89 years at the time of death) and six healthy shoulders on T1-weighted, T2 (TSE)-weighted, STIR and PD (fat saturated) magnetic resonance imaging (MRI) and compared the findings with observations during dissection and histological examination.

RESULTS

Macroscopic examinations showed two wedge-shaped disks underneath the superior and above the inferior joint capsule in nine specimens. In two specimens the acromioclavicular joints were degenerated. Histologically, the disk tissue consisted of fibrocartilage whereas the joint cartilage was partly degenerated, containing zones of fibrocartilage amidst degenerated hyaline cartilage, which may explain the similar signal intensity of both structures in all sequences used. MR appearance of the intraarticular structures of the acromioclavicular joint was similar in cadaveric and healthy shoulders.

CONCLUSIONS

The difficulties related to imaging the acromioclavicular joint may be explained by the anatomy. Similar signal intensity of cartilage and disk may be explained by their similar histological structure (fibrocartilage). MRI findings should be interpreted with respect to the variable anatomy. These results may serve as a basis for further radiological studies of the acromioclavicular joint.

Erste Ergebnisse nach Implantation einer Pyrocarbonprothese bei Mittelgelenksarthrose

AIM

Evaluation of an unconstrained pyrocarbon prosthesis (Ascension) in the treatment of idiopathic degenerative arthritis of the proximal interphalangeal joint of the hand.

METHODS

In this study 10 patients (13 implants), that were treated with this type of prosthesis between February 2002 and January 2005 were clinically and radiologically studied.

RESULTS

All but one patient were satisfied with the postoperative situation and would agree to another operation. A significant pain reduction was observed. The average ROM was 58 degrees. Five patients demonstrated a free extension, two patients had a swan neck deformity, which could be actively compensated for, and the remaining six patients had an extension deficit of 30-45 degrees. The average flexion was 76 degrees (+/-12 degrees). X-ray examination was unremarkable in eight patients with a regular position of the endoprosthesis. However, in five patients significant radiolucent lines (>or=1 mm) were observed. So far, a luxation of the prosthesis has not occurred and all implants are still in-situ. However, a dorsal tenoarthrolysis had to be performed in 3 patients.

CONCLUSION

The results of this study show a high rate of patient satisfaction with a significant pain reduction. A missing osteointegration may be an explanation for the radiological results. The prosthesis has to be closely monitored in the future. Long-term results with a higher number of patients are necessary. A central registry for finger implants is recommended.

[Update on rheuma-orthopedics - role and therapeutic options]

Orthopaedic treatment options for rheumatological patients have been further developed over recent years. For orthopaedic treatment, a range of different interventions are offered: orthoses and special technical aids as well as injections for joints and tendons, or surgery. Surgical interventions cover joint preservation, restitution and arthrodeses. Improvements in equipment and surgical procedures also make minimally invasive interactions possible for rheumatoid diseases. Thus, postoperative morbidity has been reduced significantly. Improvement in function, reduction of pain and prevention of recurrent local inflammation are primary. Considering these aims, arthrodeses are restricted to special indications. Joint preservation and restitution are the predominant measures used. The various procedures are discussed.

Correlation of ultrasonographic findings to Tossy's and Rockwood's classification of acromioclavicular joint injuries

The aim of this study was to examine the value of ultrasonography to assess high-graded acromioclavicular (AC) joint injuries. We propose a new sonographic technique to evaluate the state of the soft tissues, specifically the deltoid and trapezoid muscles and their common fascia. Radiologic findings graded by Tossy's and Rockwood's classification were compared with sonographic findings for 92 patients with high-grade injuries of the AC joint. Of the 92 patients, 39 underwent operative treatment. A total of 36 patients were radiographically classified as type II and 56 with type III injuries, according to Tossy. In 4 cases, ultrasonography displayed disrupted insertions of the deltoid and, in 30 patients, of the trapezius muscle. All patients classified as type V, eight of 18 patients classified as type IV, nine of 31 patients classified as type III and two of 28 patients classified as type II injuries, according to Rockwood's classification, displayed a disrupted deltoid and trapezius insertion and common fascia on ultrasound (US). Comparison between sonographic and intraoperative findings revealed a sensitivity for diagnosing delta muscle detachment and fascial disruption of 100%. No true-negative results occurred. For trapezius muscle detachment, 24 of 30 patients were diagnosed correctly and nine true-negative results occurred. False-positive results were not encountered. The sensitivity was 80%. The specificity was 100%. We conclude that US provides additional information concerning soft tissues and that it may be useful to delineate type III injuries, in which nonoperative vs. operative treatment is still being debated. Diagnosis based only on sagittal X-ray examination may under- or over-estimate the soft tissue injury involved. Additional transaxillary X-ray as well as an US evaluation may need to be included in the diagnostic process. We propose this new sonographic technique for future studies.

Adenocarcinoma of the rectum in childhood following chemotherapy and radiotherapy for a rhabdomyosarcoma--a case report

We report a case of rectal adenocarcinoma in a 9-year-old boy, which took the form of a second malignant neoplasm following treatment for an early childhood malignancy. The abdominal complaints were for a long time interpreted as an infectious disease. At the time of diagnosis of the rectal carcinoma, the tumor had already progressed to the stage of metastatic disease. Therapy consisted of deep anterior rectal resection and regional arterial chemotherapy for liver metastases. The child died 18 months after the diagnosis of rectal carcinoma. As survival for childhood tumors improves, rare second malignant neoplasms will become increasingly common in children and adolescents. This phenomenon emphasizes the need for continued clinical surveillance of patients who have been treated with chemotherapy or irradiation for childhood tumors. The increased risk of second malignant neoplasms and an early onset of adult-type tumors has to be considered.

Effektivität der Physiotherapie in Eigenregie bei Rotatorenmanschettendefekten

AIM

Although the outcome of surgical treatment of rotator cuff tears is well documented in the literature, less is known about the efficacy of home exercises for symptomatic rotator cuff tears in correlation to the size of the defect.

METHODS

A series of 30 patients (38 shoulders) with rotator cuff tears seen by ultrasonography were included in this prospective study. Rotator cuff tears were divided into partial defects (group A), full thickness tears of the supraspinatus tendon (group B), and massive rotator cuff defects (group C). Treatment consisted of a home program of stretching and strengthening exercises that were performed by the patients daily for a period of 12 weeks and controlled by a physician every 2 weeks. Range of motion, a modified constant score, and impingement signs at initial examination and after 12 weeks were compared.

RESULTS

All groups experienced improvement in range of motion. The Constant scores improved significantly (p < 0.05) in all groups (A: 13.0 [+/- 7.9 SD], B: 13.2 [+/- 11.4 SD], and C: 17.5 [+/- 6.6 SD]). Impingement signs showed a downward trend in all groups.

DISCUSSION

The results of this study show that patients with rotator cuff defects do benefit from simple home exercises independent from the size of the defect.

Wertigkeit der Ultraschalldiagnostik des Acromioclaviculargelenks. Ein Vergleich mit kernspintomografischen Messungen

INTRODUCTION

Ultrasound is useful in detecting acromioclavicular pathologies in cases of trauma, inflammations and degenerative changes in sports medicine. Many studies compare joint space and capsular dimensions of symptomatic and asymptomatic patients. However, no study has examined the reproducibility and reliability of these measurements. The aim of this study was to evaluate the reliability of ultrasonographic measurements in assessing the acromioclavicular joint.

MATERIALS AND METHODS

27 acromioclavicular joints of 15 healthy subjects were examined by T1 weighted magnetic resonance imaging (MRI) to determine the normal limits of joint space (a) and joint capsule (b). These measurements were compared to standardised ultrasonographic (11 Mhz) measurements, which were repeated three times.

RESULTS

The mean difference between MRI and ultrasound measurements was 1.5 +/- 1.3 mm and 1.3 +/- 1.2 mm for distance a and b, respectively. Reproducibility of ultrasonographic measurements was high with a mean standard deviation of 0.3 +/- 0.2 mm and 0.4 +/- 0.3 mm for distance a and b, respectively.

CONCLUSION

Due to low costs, safety and wide availability ultrasonography is suited for the evaluation of the acromiocalvicular joint. However, when interpreting the results measurement errors, limitations in resolution of the system used, and the anatomy of the acromioclavicular joint and its anatomic variants have to be taken into consideration.

[Influence of sequence type on the extent of the susceptibility artifact in MRI--a shoulder specimen study after suture anchor repair]

PURPOSE

To compare the extent of susceptibility artifacts after metallic suture anchor implantation by analyzing 14 different MRI sequences.

MATERIALS AND METHODS

A metallic suture anchor was implanted in the central area of three glenoid porcine specimens. The specimens were imaged with a 1.5 T scanner using a protocol of 14 standard sequences including gradient echo, spin echo and turbo spin echo sequences with and without fat-saturation. Artifact size was measured for each specimen and sequence. The resulting mean artifact areas were determined for each type of sequence and the mean values of the three specimens compared.

RESULTS

Gradient echo-sequences produced significantly larger artifact areas than the spin echo and turbo spin echo sequences, whereby the artifacts of the 3D-gradient echo sequences were smaller than the artifacts of the 2D-gradient echo sequences. A turbo spin echo sequence with a high readout band width and a short effective echo time showed the best results. For the conventional spin echo sequence, a reduction in the echo time did not significantly decrease the artifact size. Spectral fat-saturation did not affect the area of the susceptibility artifact compared to the non-saturated sequence.

CONCLUSION

Gradient echo sequences should not be used after metallic suture anchor repair. Turbo spin echo sequences showed a decrease in the artifact size compared to conventional spin echo sequences and should be performed with a short effective echo time and a high band width. Spectral fat- saturation did not increase the artifact size significantly.

Biomechanical effect of patch graft for large rotator cuff tears: a cadaver study

It is not possible for some rotator cuff tears to be repaired because of a large defect associated with muscle retraction. The purpose of the current study was to investigate the use of a synthetic patch graft to restore abduction force transmission in the glenohumeral joint with a rotator cuff defect. Shoulders from cadavers (n = 10) were fixed in the hanging arm and in neutral rotation, and loading was applied to the rotator cuff tendons and middle deltoid. After a simulated supraspinatus tendon defect and retraction, a patch graft was inserted into the defect and the effects of reattachment to the greater tuberosity, narrowing of the defect by using a smaller graft, and anterior graft attachment (rotator interval tissue versus subscapularis) were investigated. Abduction torque generation was measured and normalized to the intact condition. Compared with torque generation after creation of a supraspinatus defect (61% of normal torque), abduction torque increased with a graft between the infraspinatus and either the rotator interval (68% of normal) or subscapularis (80% of normal). The optimum grafting technique for abduction torque restoration occurred with a reduced size patch connected anteriorly to the subscapularis and sutured to the greater tuberosity (107% of normal). The patch graft acts to redirect force transmission, thereby providing a potential treatment option for otherwise irreparable defects. These same principles can be applied when tendon transfers are used to reconstruct large or massive cuff tears.

Measurement of muscle activity with magnetic resonance elastography

OBJECTIVE

To non-invasively determine muscle activity.

DESIGN

A correlation analysis study.

BACKGROUND

Electromyography is traditionally used to measure the electrical activity of a muscle and can be used to estimate muscle contraction intensity. This approach, however, is limited not only in terms of the volume of tissue that can be monitored, but must be invasive if deep lying muscles are studied. We wished to avoid these limitations and used magnetic resonance elastography in an attempt to non-invasively determine muscle activity. This novel approach uses a conventional MRI system. However, in addition to the imaging gradients, an oscillating, motion sensitizing field gradient is applied to detect mechanical waves that have been generated within the tissue. The wavelength correlates with the stiffness of the muscle and hence with the activity of the muscle.

METHODS

Six volunteers (mean age: 30.1 years, range: 27-36 years) without orthopedic or neuromuscular abnormalities, lay supine with their legs within the coil of a MRI scanner. The wavelengths of mechanically generated shear waves in the tibialis anterior, medial and lateral head of the gastrocnemius and the soleus were measured as the subjects resisted ankle plantar-flexing (8.2 and 16.4 nm) and dorsi-flexing (20.2 and 40.4 nm) moments. The findings were then compared to EMG data collected under the same loading conditions.

RESULTS

Magnetic resonance elastography wavelengths were linearly correlated to the muscular activity as defined by electromyography. (TA, R(2)=0.89, P=0.02; MG, R(2)=0.82, P=0.05; LG, R(2)=0.88, P=0.03; S, R(2)=0.90, P=0.02)

CONCLUSIONS

Magnetic resonance elastography may be a promising tool for the non-invasive determination of muscle activity.

RELEVANCE

Magnetic resonance elastography has potential as the basis for a new non-invasive approach to study in vivo muscle function.

The effect of infraspinatus disruption on glenohumeral torque and superior migration of the humeral head: a biomechanical study

Rotator cuff ruptures that extend into the infraspinatus tendon may cause dysfunction and superior migration of the humerus. The purpose of this study was to determine whether a threshold size of infraspinatus defect exists beyond which abduction torque generation decreases and superior migration of the humeral head increases. Glenohumeral abduction torque and superior humeral head translations were measured in hanging arms in neutral rotation in cadaver shoulders (n = 10). Loads were applied to the rotator cuff tendons and the middle deltoid. After sequential detachment of the infraspinatus, abduction torque progressively decreased. At three-fifths detachment, abduction torque was significantly lower than after supraspinatus release alone (52% vs 61%, P <.05). Superior translation after complete supraspinatus and infraspinatus detachment increased significantly (P <.05), but no intermediate threshold was detected. Therefore, the entire infraspinatus contributes to abduction torque generation and stabilizes the humeral head against superior subluxation. Even with a tear extending into the superior infraspinatus, the infraspinatus contributes abduction force generation across the glenohumeral joint.

Gliding properties of the long head of the biceps brachii

To elucidate the role of mechanical forces that resist motion of the long head of the biceps brachii, the gliding resistance of the tendon during abduction and adduction was measured. Nine human cadaveric glenohumeral joints were obtained (mean age 68 years, range 47-84). A testing device was developed to simulate glenohumeral abduction and adduction motion. Gliding resistance was calculated as the force differential on the proximal and distal ends of the biceps brachii at five glenohumeral angles (15 degrees, 30 degrees, 45 degrees, 60 degrees and 75 degrees ). The average gliding resistance in abduction at 15 degrees, 30 degrees, 45 degrees, 60 degrees and 75 degrees for a 4.9 N load was 0.41, 0.40, 0.36, 0.32 and 0.28 N, respectively. At these same angles, but during adduction motion, the force on the proximal tendon end was either identical or less than the distal tendon end (p>0.46) indicating a lack of resistance and even a phenomena of "negative" resistance in which some other force overcame the friction. The difference in gliding resistance between abduction and adduction was significant (p<0.05). The results indicate that forces opposing biceps tendon gliding are more complicated than simply due to friction. Tendon deformation inside the bicipital groove produces a direction-dependent effect due to a mechanism of elastic recoil. Understanding forces that are absorbed by the tendon during active motion may provide insight into pathological changes that develop inside and around the tendon.

Evaluation of healthy and diseased muscle with magnetic resonance elastography

OBJECTIVE

To investigate whether a new tissue-imaging technique, magnetic resonance elastography (MRE), offers a viable, noninvasive way to study healthy and diseased muscle.

DESIGN

Convenience sample.

SETTING

A magnetic resonance imaging (MRI) laboratory.

PARTICIPANTS

Eight control subjects (4 men, 4 women), between the ages of 24 and 41 years, with normal neuromuscular examinations and histories, and 6 subjects (3 men, 3 women), ages 17 to 63 years, with lower-extremity neuromuscular dysfunction (1 with childhood poliomyelitis, 2 with flaccid, 3 with spastic paraplegia).

INTERVENTIONS

Subjects lay supine with their legs within the coils of a 1.5T MRI machine, with their feet strapped to a footplate positioned so that the axes of rotation of their ankles coincided with the apparatus. All subjects were tested in a no-load (0 torque) condition. Control subjects were also evaluated as they isometrically resisted ankle dorsi- (20.2Nm, 40.5Nm) and plantar- (8.2Nm, 16.4Nm) flexion moments. Subjects with neuromuscular dysfunction were evaluated in the same manner, except 1 individual with residual lower-extremity strength who could only be tested in the resting and passive ankle dorsiflexion modes. Shear waves were induced with a 150-Hz electromechanic transducer located over the belly tibialis anterior. MRE images were collected with a gradient-echo technique gated to the transducer's motion. Wave-phase propagation was visualized with 8 equally offset images across 1 vibration-cycle.

MAIN OUTCOME MEASURES

Changes in shear-wave wavelength (lambda) and muscle stiffness (as expressed by the shear modulus [G]) in the tibialis anterior and gastrocnemius muscles.

RESULTS

Wavelength and G differed between the groups in all the muscles studied, and increased as the load increased. Moreover, lambda and G in the neuromuscular disease group at rest (eg, 3.88+/-0.48cm; range, 2.87-4.91cm; 38.40+/-00.77kPa; range, 22.35-59.67kPa) and in the lateral gastrocnemius were, respectively, more than 1.5 and 2.4 times larger than they were in the same muscle in the control group (2.56+/-0.28cm, 16.16+/-00.19kPa; P=.0002) (1Pa=1N/m(2)).

CONCLUSIONS

Shear-wave wavelength and muscle stiffness increased with load in healthy muscle. In addition, at least for our sample, these quantities differed significantly between muscles with and without neuromuscular disease. In summary, MRE appears to provide in vivo physiologic information about the mechanical properties of muscle at rest and during contraction that is not otherwise available. The potential of this technique for monitoring the effects of treatment and exercise on both healthy and diseased muscle merits further research.

Biomechanical comparison of effects of supraspinatus tendon detachments, tendon defects, and muscle retractions

BACKGROUND

Rotator cuff ruptures are frequently associated with loss of strength of the shoulder. However, the characteristics of the rotator cuff tear that are responsible for the loss of force generation and transmission have not yet been identified. The purpose of this study was to compare the effects of supraspinatus tendon detachments, tendon defects, and muscle retractions on in vitro force transmission by the rotator cuff to the humerus.

METHODS

The rotator cuff tendons from ten cadaver shoulders were loaded proportionally to the respective cross-sectional areas of their muscles. A fiberglass rod was cemented into the medullary canal of the humerus and connected to a three-component load cell for the measurement of the forces transmitted by the rotator cuff to the humerus. This study was performed with the humerus in a hanging arm position and with various sizes of supraspinatus tendon detachments, tendon defects, and muscle retractions.

RESULTS

Detachment or creation of a defect involving one-third or two-thirds of the supraspinatus tendon resulted in a minor reduction in the force transmitted by the rotator cuff (< or =5%), while detachment or creation of a defect involving the whole tendon resulted in a moderate reduction (11% and 17%, respectively). Simulated muscle retraction involving one-third, two-thirds, and the whole tendon resulted in losses of torque measuring 19%, 36%, and 58%, respectively. Side-to-side repair of the one-third and two-thirds defects nearly restored the force transmission capability, whereas a deficit remained after side-to-side repair following complete resection.

CONCLUSIONS

Our results support the rotator cable concept and correspond to the clinical observation that patients with a small rupture of the rotator cuff may present without a loss of shoulder strength. Muscle retraction is potentially an important factor responsible for loss of shoulder strength following large rotator cuff ruptures.

CLINICAL RELEVANCE

Supraspinatus muscle retraction diminishes glenohumeral abduction torque significantly more than either a defect in the tendon or a simple detachment of the tendon from the tuberosity. In cases of irreparable defects, side-to-side repair may be worthwhile to restore muscle tension and the integrity of the rotator cable.

[Ultrasound diagnosis of the acromioclavicular joint]

Although standardized sonographic techniques are available, the diagnostic capabilities of sonography in diseases and injuries of the acromioclavicular [AC] joint are not yet widely used. Nevertheless, standardized sonographic techniques are available for examining injuries and diseases of the AC joint. Analogous to X-ray techniques, the bony relations of the clavicle and the acromion can be displayed. Joint effusions and marginal alterations of the subchondral bone plate can be imaged. However, there is no reliable method to display the articular disc and the coracoclavicular ligaments. There is no reproducible method for displaying the articular disk. Tears of the deltoid and trapezius muscles and their common fascia are easily detectable in high-grade injuries of the AC joint. The differentiation between acjoint injuries, i.e. Rockwood II/Rockwood IV, is facilitated, which aids in therapeutic decision making. In combination with conventional X-ray examination, sonography of the AC joint can be used at low cost and is easy to learn.

Ultrasound-guided decompression of the spinal canal in traumatic stenosis

The purpose of this study was to examine the efficacy of ultrasound (US)-guided decompression of the myelon in the surgical treatment of spinal fractures. Intraoperative ultrasonography was performed in 22 patients with traumatic stenosis of the spinal canal during spinal cord surgery with removal of retropulsed bony fragments. US imaging requires a posterior approach and an enlarged foramen interarcuale. The posterior vertebral facet and the myelon can accurately be distinguished from small bony fragments by ultrasonography. Pre- and postoperative computed tomography was compared with intraoperative US imaging. Complete decompression of the spinal canal was controlled by US imaging of the restored ventral epidural space, as seen after repositioning of displaced fragments. Thus, the required extent of the surgical procedure was determined by intraoperative ultrasonography. We conclude that intraoperative US imaging is an important tool to monitor the restoration of the spinal canal and decompression of the spinal cord in case of fracture. The repositioning of stenosing bony fragments using surgical instruments can be monitored. US imaging as a real-time method intraoperatively provides the surgeon with additional information and significantly influences treatment options.

[Principles of shoulder prosthesis implantation]

Patients with an intact rotator cuff and a humeral head that is centered in the glenoid fossa will benefit from both: a hemiarthroplasty and a total shoulder arthroplasty. However, the functional outcome following total shoulder arthroplasty is superior to that of hemiarthroplasty. Superior migration or mal-positioning of the humeral head in the anterior or posterior direction are generally associated with a maximum active flexion of 90 degrees and a high rate of loosening of the glenoid component. Total shoulder arthroplasty leads to superior results in patients with osteoarthritis and mal-positioning of the humeral head in the posterior direction. However, if the head can not be centralized in the glenoid fossa a significant risk of glenoid loosening remains. A superior functional outcome of total shoulder arthroplasty in patients with rheumatoid arthritis can be observed. On the other hand inferior bone quality and a rotator cuff might lead to loosening of the glenoid component. Radiographic signs of glenoid loosening are frequently observed. However, these hardly require operative revisions. If a glenoid component can not be inserted, a bipolar or inverse prosthesis might be considered an alternative.

[Biomechanical considerations on shoulder joint prosthesis implantation]

The biomechanical goals of prosthetic reconstruction of the shoulder are to restore the normal anatomy and range of motion, and to recreate the normal soft tissue balance of the static and dynamic stabilizers of the glenohumeral joint. An unconstrained prosthesis design best reproduces the physiological articulation and original anatomy of the shoulder. Humeral head components have been recently developed, which are adaptable to the variable anatomy of the proximal humerus (third generation design). A precise reconstruction of the three dimensional structure of the proximal humerus may lead to an improved functional outcome. However, there is still a lack of biomechanical data to support this concept. The optimal design of the glenoid component remains a challenge for future research. Specific issues including the choice of biomaterials, the optimum shape, radius of curvature, surface area of the articulation, component height and stem design remain under investigation. Although the prosthetic design represents an important factor in the success of glenohumeral arthroplasty, the surgical reconstruction of the soft tissues to recreate the normal soft tissue balance as well as postoperative rehabilitation determine the functional outcome.

[Shoulder hemi-arthroplasty in proximal humeral fractures]

Most fractures of the proximal humerus with significant displacement are best treated surgically. The range of surgical treatment varies from closed reduction and pinning to hemiarthroplasty depending on the degree of displacement, age of the patient, and bone quality. Determining whether or not the individual fractured bone segments are displaced to a significant degree requires high quality x-rays which can be difficult to obtain from acutely injured patients. Indications for replacement of the humeral head in acute fractures include: head splitting fractures in elderly patients, Neer 4-part fracture dislocations, selected 3 part fractures and fracture dislocations in elderly patients with poor bone quality and a very small head fragment, selected severe impression fractures in elderly patients that involve more than 40% to 50% of the articular surface and selected anatomical neck fractures in which internal fixation is not possible. If a prosthetic replacement of the humeral head is chosen, secure repair of the tuberosities is essential to avoid tuberosity migration and malunion. The clinical results of prosthetic replacement of the proximal humerus for acute fractures are superior to those for late arthroplasty. This treatment modality has been proven to relieve pain. However, even for patients treated with primary arthroplasty, a restricted range of motion has to be expected postoperatively. Furthermore, several studies indicate that a significant number of complications can occur following early and late prosthetic replacement. Humeral head replacement as a salvage procedure after malunions or failed open reduction and internal fixation is technically demanding with a relatively high rate of complications. Newer implant designs and instruments may improve the clinical results.

[Surgical approach in lumbar intervertebral disk displacement. Topographical principles and characteristics]

For the operative procedure in lumbar disc extrusion it is important to expose the prolapsed disc and sequestrum without disintegration of the musculature and branches of r. dorsalis nervi spinalis or provoking lesions in the spinal canal. A classification helps to determine exact description of localization of disc material in craniocaudal and mediolateral directions. It can be correlated with the interlaminar window as a structure seen in the operative procedure. A speculum helps to limit the exposure for an interlaminar as well as a lateral access, thus reaching the structures concerned in the spinal canal with minimal irritation of the surrounding tissues. For interlaminar access partial excision of the lig. flavum is sufficient. The extrusions in the foraminal region that can be exposed laterally from a medial skin incision, as well as from a paramedial are between m. multifidus and m. longissimus. In revision surgery, the upper laminar corner is advantageous for entering the spinal canal.

Topographical principles and peculiarities of operative access in lumbar disc extrusion

For the operative procedure in lumbar disc extrusion it is important to expose the prolapsed disc and sequestrum without disintegration of the musculature and branches of r. dorsalis nervi spinalis or provoking lesions in the spinal canal. A classification helps to determine exact description of localization of disc material in craniocaudal and mediolateral directions. It can be correlated with the interlaminar window as a structure seen in the operative procedure. A speculum helps to limit the exposure for an interlaminar as well as a lateral access, thus reaching the structures concerned in the spinal canal with minimal irritation of the surrounding tissues. For interlaminar access partial excision of the lig. flavum is sufficient. The extrusions in the foraminal region that can be exposed laterally from a medial skin incision, as well as from a paramedial are between m. multifidus and m. longissimus. In revision surgery, the upper laminar corner is advantageous for entering the spinal canal.

[The lumbar ligamentum flavum. Anatomic characteristics with reference to microdiscotomy]

One important step in lumbar discotomy is the safe penetration and exact partial removal of the Lig. flavum. This is a crucial prerequisite for the selective and gentle removal of prolapsed and sequestrated intervertebral disc tissue. Extensive lancing of the Lig. flavum should be avoided, to minimize intraoperative and postoperative complications, such as injuries to the nerves and the Dura mater, instabilities, bleeding and scarring. As there has up to now been insufficient information on the anatomy of the Lig. flavum especially regarding microdiscotomy, an analysis of the Ligg. flava L2/L3 to L5/S1, guided by this aim, was carried out on 36 corpses kept in formaline (16 f, 20 m; 52-78 y). Preparations showed the lumbar Ligg. flava to be embodied in the Foramina interarcualia in a characteristic configuration. There also proved to be defined insertion areas on the laminae of the vertebral arches, which must be taken into consideration during the operative exposure. The Lig. flavum rises from the cranial vertebral arch from the ventral surface of the lamina (6.8 mm) whilst the insertion area on the caudal lamina covers the dorsal and the ventral surface. The extent at the ventral surface is 2.2 mm in average. Taking the insertion proportions into account we would suggest the Lig. flavum to be divided as follows: Pars interspinalis, which clearly differs from the Lig. interspinale (and from the M. interspinalis), and which houses venous anastomoses in its dorsal, ridge-shaped extension. Pars interlaminaris, which starts at the laminae and constitutes the target area for flavotomy in its lateral section, and Pars capsularis, which merges into the capsular structures of the facets. In all levels examined, there proved to be dorso-ventrally a typical change in the direction of the course of the fibres in the Pars interlaminaris. Whilst the direction of the fibres dorsally is oriented cranio-medially to caudo-laterally at an angle between 15 degrees and 30 degrees to the median line, the ventral fibres of the Lig. flavum are strictly aligned cranio-caudally. The changes in the directions of the fibres are continuous with the fibres being very closely intertwined, without there being any spatium at all. The texture of the Lig. flavum is, therefore, a mirror image of that of the autochthonuous muscular system of the back, even if the overlapping angle area is considerably smaller. The different segment levels show a segment-specific thickness profile. The analysis has provided anatomic information about the Ligg. flava L2/L3 to L5/S1. These data represent important prerequisites for a selective, gentle and safe intraoperative procedure for discotomy.