Biomedical subjects

J Kärrholm

Publications and source records attributed to J Kärrholm.

At least 19 recordsLinked to original sources

PubMed2006

Shoulder kinematics in 25 patients with impingement and 12 controls.

UNLABELLED: We used dynamic radiostereometry to study the three-dimensional kinematics of the shoulder joint during active abduction. Twenty-five patients experiencing shoulder symptoms (Neer Stage 2) for more than 18 months, without total rotator cuff tears, participated. Eight men and four women without shoulder symptoms constituted controls. The rotation of the humeral head relative to a fixed scapula and the absolute rotation of the humerus (caused by humeral, scapular, and trunk motion) were measured. The rotations were calculated in the order of abduction/adduction (anteroposterior axis), internal/external rotation (longitudinal axis), and flexion/extension (transverse axis). The absolute abduction of the humerus in our patients did not differ from controls, nor did the abduction in the glenohumeral joint. During abduction, the humeral centre displaced medially, proximally, and anteriorly. In the patient group, slightly more (1-1.5 mm) proximal translation was observed. Presence of impingement syndrome was associated with increased proximal translation of the humeral head center, which occurred in the early phase of the arc of motion. LEVEL OF EVIDENCE: Diagnostic Level I. See Guidelines for Authors for a complete description of Levels of Evidence.

Adult↗

PubMed2005

Is increased segmental motion early after lumbar discectomy related to poor clinical outcome 5 years later?

The purpose of the study was to compare segmental motion in the early postoperative phase after lumbar discectomy to the outcome 5 years postoperatively. The study population had radiologically verified symptomatic L4-L5 or L5-S1 lumbar disc herniation and was referred with an indication for lumbar discectomy. Radiostereometry was performed in the supine and standing positions. The L4-L5 and L5-S1 segments were analysed separately. L4-L5 segments adjacent to the operated L5-S1 segment constituted a reference segment for the operated L4-L5 and vice versa. Twenty-one patients were available for the follow-up at 5 years. Outcome was classified as functionally good or poor. Repeated or planned repeat surgery at the same level during follow-up was considered as poor outcome. The L4-L5 segments in the poor group showed different direction of sagittal rotation (anterior versus posterior) of L4 on L5 compared with the good group (p<0.01). On the L5-S1 segment, patients with poor outcome displayed an increased anterior translation of about 1 mm (p<0.01) compared with the reference segments. Our study suggests that increased inducible vertebral displacement in the early postoperative phase after discectomy is associated with a poor clinical outcome.

Adult↗

PubMed2005

The effect of standard lumbar discectomy on segmental motion: 5-year follow-up using radiostereometry.

We measured the effects of lumbar discectomy on segmental motion over a period of 5 years. Twenty-four patients with lumbar disc herniation were treated by standard lumbar discectomy at the L4-L5 or L5-S1 level. Peroperatively, tantalum markers were inserted into L4, L5, and the sacrum. Radiostereometric analysis was performed at discharge from hospital and 5 years postoperatively. The treated level was compared with the corresponding untreated level. Thus, patients who had discectomy at the L4-L5 level served as controls for patients with L5-S1 lesions and vice versa. The relative rotation and translation in relation to the three cardinal axes were calculated. Inducible displacements over the two discs were calculated between the supine and standing positions. At the L4-L5 level, there were no differences in inducible displacements between the operated and control levels at discharge or 5 years postoperatively. At the L5-S1 level we found decreasing inducible movement in the sagittal plane over time for discectomy patients. The reason for decreasing mobility over time after discectomy at the L5-S1 but not at the L4-L5 level is unknown. Mechanical factors caused by the more vertical orientation of the L5-S1 disc in combination with degenerative changes could be one explanation.

Adult↗

PubMed2005

Imaging knee position using MRI, RSA/CT and 3D digitisation.

The purpose of this study was to compare 3 methods of imaging knee position. Three fresh cadaver knees were imaged at 6 flexion angles between 0 degrees and 120 degrees by MRI, a combination of RSA and CT and 3D digitisation (in two knees). Virtual models of all 42 positions were created using suitable computer software. Each virtual model was aligned to a newly defined anatomically based Cartesian coordinate system. The angular rotations around the 3 coordinate system axes were calculated directly from the aligned virtual models using rigid body kinematics and found to be equally accurate for the 3 methods. The 3 rotations in each knee could be depicted using anatomy-based diagrams for all 3 methods. We conclude that the 3 methods of data acquisition are equally and adequately accurate in vitro. MRI may be the most useful in vivo.

Cadaver↗

PubMed2005

Medial and lateral osteoarthritis of the knee is related to variations of hip and pelvic anatomy.

OBJECTIVE: We evaluated if increased risk of combined hip and lateral knee osteoarthritis (OA) could be attributed to anatomical reasons in the hip region resulting in increased abductor moment over the knee. METHODS: We measured pelvic width, femoral offset, femoral neck length and angle in 29 women with lateral knee OA (13 unilateral, 16 bilateral) and 27 women with bilateral medial OA. Twenty-one of these patients with normal hips (lateral/medial OA of the knee=12/9) and 35 with associated hip OA (lateral/medial OA of the knee=17/18) were evaluated separately. Radiographic examinations in 14 women planned for hip prosthesis because of failures after hip fracture acted as controls. RESULTS: Patients with lateral OA of the knee had wider pelvis than controls (13.7 mm increased distance between the medial borders of the acetabulum, P=0.001). Patients with medial OA had 11.4mm longer distance from the centre of the femoral head to the centre of the proximal part of the femoral shaft (P=0.005), corresponding to a higher offset. The pelvic and hip anatomy also differed between patients with medial and lateral OA of the knee. In the groups without hip OA, presence of lateral knee OA was associated with a wider pelvis (P=0.009), shorter femoral neck (P=0.02) and Head-Shaft distance (P=0.04). In the groups with OA of the hip associated lateral OA of the knee also implied increased Neck Shaft angle (coxa valga, P=0.008), but there was no difference in pelvic width (P=0.15). We found a shorter lever arm over the hip in lateral knee OA compared to medial knee OA (P=0.02), but not when compared to controls. CONCLUSION: Our findings suggest that occurrence of medial or lateral OA has a biomechanical background originating from pelvis and hip anatomy.

Female↗

PubMed2001

The influence of fracture etiology and type on fracture healing: a review of 104 consecutive tibial shaft fractures.

This study was conducted to determine retrospectively the factors which influence fracture healing and risk for nonunion in patients with tibial shaft fractures. One hundred consecutive patients with 104 tibial shaft fractures and a mean age of 40 (14-85) years were reviewed. Fractures were classified according to the AO classification system. There were 22 open fractures and 52 comminuted fractures. Thirty-eight fractures were caused by high-energy trauma. Fracture pattern, soft-tissue condition, level of energy of the trauma, malalignment, and treatment methods were identified. The influence of these factors on the time of hospital stay and sick-leave, delayed union, and nonunion were calculated. Normal healing occurred in 61 fractures with a mean healing time of 17 weeks, delayed union in 27 with a mean of 35 weeks, and nonunion in 16 with a mean of 69 weeks. The relative risk of developing nonunion in open fractures was 8.2 (CI = 2.9-10.5) and 2.9 (CI = 1.2-3.2) in fractures exposed to high-energy trauma. This study showed that the soft-tissue condition and level of trauma energy are good predictors for the development of complications. Considering these risk factors at an early stage in the planning of treatment might reduce the risk of nonunion. ergy level of the trauma, fracture comminution, initial fracture displacement, treatment method, contamination, and associated injuries will influence fracture healing. Conservative treatment has in general been recommended for undisplaced closed or grade I open fractures caused by low-energy trauma [15, 18, 21]. However, conservative treatment of a tibial shaft fracture means immobilization of the lower leg for a long period of time, especially if healing is delayed. Thus, it is important to consider the risk of healing complications when planning the appropriate treatment method in the early stage after the injury. The purpose of this study was to analyze complications such as delayed union and nonunion and to identify factors which affect the healing of tibial shaft fractures.

Adolescent↗

PubMed2001

Deformation across the zone of callotasis during loading. radiostereometric analysis in a patient with achondroplasia.

The present study demonstrates that high-resolution radiostereometric analysis (RSA) can be used to assess global longitudinal compressive deformation across the callotasis zone during loading. In an achondroplastic patient operated with bifocal lengthening of the tibia by use of the Ilizarov external fixator, the axial compressive intersegmental strain in the proximal lengthening zone under a load of 71% of body weight was 7.7 mm. The proximal lengthening zone was 51.0 mm, and accordingly the overall linear strain across the callotasis was 15.1%. This large strain value found in distraction osteogenesis 6 weeks after end of distraction is not consistent with classical theory of the magnitude of micromotion needed for adequate stimulation of bone formation in fracture healing. The increased axial displacement did not stimulate bone healing and delayed union was observed. This one single observation does not allow for any conclusions to be drawn about the relationship of strain to fracture healing, but further and refined use of the RSA method will certainly improve our understanding of the role of axial strains in distraction osteogenesis.

Achondroplasia↗

PubMed2001

Inducible displacements of cemented tibial components during weight-bearing and knee extension observations during dynamic radiostereometry related to joint positions and 2 years history of migration in 16 TKR.

The inducible displacements of the tibial component caused by active extension were studied in 16 knees 1 yr after an AMK total knee arthroplasty with either flat. concave or posterior-stabilised (PS) designs of the joint area. Continuous change of the position of the tibial component occurred with proceeding extension. Rocking, subsidence and lift-off at different localisations were observed. In 3 of 4 knees with flat inserts the tibial component tilted anteriorly from 45 degrees to 35 degrees of flexion. A similar anterior tilt was seen in 2 of 6 with concave inserts and 5 of 6 with the PS design, but the tilting started later, when the knee had 5-20 degrees more extension. From 45-15 degrees of flexion most components tilted into valgus. Three knees (1 concave with, 1 concave without PCL and 1 PS) showed a sudden tilt into varus direction followed by a rocking motion in the opposite direction. The other types of displacements studied showed a more uniform pattern. The inducible maximum translation (MTPM) at 20 degrees of extension tended to be associated with increased migration between 0 and 2 yr when measured with the same parameter (Spearman's rho = 0.54, P = 0.03). Increased medial displacement of the center of the proximal tibia at 25 degrees was associated with increased anterior tilt. This type of motion was most commonly seen with the concave design. Our observations demonstrate that the forces acting on the tibial component vary during active extension, which results in rocking movements. This will influence the migration and the patttern of wear, factors of importance for the clinical longevity of a total knee replacement (TKR).

Aged↗

PubMed2001

Concave versus posterior-stabilized tibial joint surface in total knee arthroplasty: randomized evaluation of 47 knees.

Forty-seven knees in 43 patients with severe deformities randomly received AMK total knee arthroplasty with concave (C, n = 25) or posterior-stabilized (PS, n = 22) polyethylene insert and with resection of the posterior cruciate ligament. Radiostereometric examinations were done postoperatively and after 3, 12, and 24 months. Two patients (1 C, 1 PS) underwent revision surgery. At the 2-year follow-up, the median absolute rotations of the tibial inserts ranged from 0.13 degrees to 0.26 degrees (C vs PS; P =.1-.7). The maximum total point motion was almost identical in the 2 groups (C, 0.38; PS, 0.39; P =.9). Maximum subsidence, lift-off, and Hospital for Special Surgery scores did not differ (P =.1-.6). Recipients of 20 of 24 knees with concave design and 14 of 19 knees with posterior-stabilized design reported that their knee could be regarded as normal or almost normal. Variations of the configuration of the polyethylene insert did not alter the outcome in the short term.

Aged↗

PubMed2001

Does metal backing improve fixation of tibial component in unicondylar knee arthroplasty? A randomized radiostereometric analysis.

In a prospective, randomized study, patients with medial gonarthrosis stage I to III according to Ahlbäck were allocated to a unicondylar knee arthroplasty (Miller-Galante, Zimmer, Inc., Warsaw, IN) with an all-polyethylene tibial component or metal-backed tibial component of the same design. The purpose of the study was to evaluate if metal backing enhanced tibial component fixation. A total of 45 knees (42 patients; 23 metal-backed components and 22 all-polyethylene components) were examined. We used radiostereometric analysis to measure micromotion of the tibial component over a period of 2 years after surgery. Hospital for Special Surgery score was used for clinical evaluation. We found no statistically significant differences in clinical results or migration of the tibial component over a 2-year follow-up period. These findings do not support better fixation of metal-backed tibial components. Because of these findings, we advocate all-polyethylene tibial components in unicondylar knee arthroplasties because of optimal biomechanical strength at a given height of tibial component, avoiding potential problems of modularity and minimizing the amount of interfaces, at a lower cost.

Aged↗

PubMed2001

Impaction technique and graft treatment in revisions of the femoral component: laboratory studies and clinical validation.

The micromotions of femoral stems cemented into impacted bone-graft were studied in 23 femora from adult sows. The model was validated against 2 patient groups. Conventional impaction technique and a new impaction technique using polished and rotating impactors were studied in the preclinical model and in 14 and 10 patients with type II defects. The specimens were loaded in an MTS (Minneapolis Testing System) machine for 72,000 cycles at 250N to 3,250N. The bone-graft was rinsed in tepid water, and most of the bone marrow and fat were removed. Radiostereometric measurements revealed small subsidence of the stems cemented into the specimens and the patients 6 weeks after the operation without any difference (median values, -0.06 to -0.16 mm). Further studies of specimens operated with nontreated bone-graft showed that extraction of fat increased the stability. Our findings suggest that the early postoperative implant stability after impaction grafting of the femur mainly is an effect of surgical technique and graft treatment. The new impaction technique, with which we hoped to obtain a more reproducible procedure and less risk for perioperative fracture, resulted in stability equal to that obtained with the conventional technique.

Animals↗

PubMed2001

Bone cement with reduced proportion of monomer in total hip arthroplasty: preclinical evaluation and randomized study of 47 cases with 5 years' follow-up.

Bone cement with reduced amount of monomer and low curing temperature may improve implant fixation due to reduced toxicity. We analyzed the mechanical, chemical and thermal properties of such a cement (Cemex Rx) using Palacos R as control. The in vivo performance of the 2 cements was also evaluated in a prospective randomized study of 47 hips, where either of the cement types was used to fixate Lubinus SP2 prostheses with the stem made of titanium alloy. Cemex Rx had a reduced tensile strength, probably because this cement was manually mixed, as recommended by the manufacturer. A standardized labor tory test showed lower curing temperature for Cemex, but measurements at 37 degrees and with prechilled Palacos R and Cemex Rx, as in clinical work, showed no difference. In the clinical study radiostereometric measurements of cup and stem migration showed similar values in the 2 groups up to 5 years after the operation. The cement mantle was stable in both groups, but the stems migrated similarly inside the cement mantle regardless of the type of cement used. Proximal wear was low (0.04-0.05 mm/year) and tended to be lower in the Cemex group (p = 0.02). Aluminum and vanadium levels in serum increased 5 years after the operation, but no difference was noted between the 2 groups. Collagen markers (PICP, ICTP) showed similar increases in bone turnover 6 weeks and 6 months after operation in both groups.

Aged↗

PubMed2001

Flat vs. concave tibial joint surface in total knee arthroplasty: randomized evaluation of 39 cases using radiostereometry.

40 patients with non-inflammatory arthrosis and minor preoperative deformity (< or =5 degrees ) were operated on with an AMK type (DePuy, Johnson & Johnson) total knee arthroplasty (TKA). The posterior cruciate ligament was retained. The patients were divided into those with a flat (terminology of the manufacturer: standard) or a concave (terminology of the manufacturer: constrained) polyethylene insert (20 in each group). Radiostereometric (RSA) examinations were done postoperatively and after 3,12 and 24 months. The median absolute rotations of the tibial inserts varied between 0.12 and 0.24 (range 0.00-1.54) degrees, with no differences between the 2 groups. The median maximum total-point motions (flat/concave = 0.41/0.42 mm), the maximum subsidence or lift-off did not differ. The Hospital for Special Surgery knee score and the patients' opinion about the operation, based on their preoperative expectations, showed little, if any, differences. At 2 years, 10 of 20 patients with flat and 13 of 19 with concave inserts regarded their knee function as normal or almost so.

Aged↗

PubMed2001

Charnley cups retained during revision of the femoral component: repeated clinical and radiographic observations of 49 cups for 7-15 years.

This article concerns 49 consecutive polyethylene cups retained in cemented first revisions of the femoral component and evaluated on several occasions 7-15 years after the index operation. At the last follow-up 5 cups were revised, 3 were radiographically loose, 1 was revised because of recurrent dislocation and 1 stable cup was revised because the surgeon wished to use a 28 mm head. Moreover, 1 unrevised cup was radiographically loose. This corresponded to a mechanical failure rate of 0.1 (5/49) and revision rate of 0.1 (4/49). 3 cups which were radiographically loose (100% radiolucency) had not been revised when the stem was exchanged. If these cups were excluded, the revision rate would have dropped to 0.02 (1/46) and the mechanical failure rate to 0.04 (2/46). This indicates the importance of careful preoperative radiographic evaluation on both AP and lateral views. Progression of radiolucent lines always occurred as an increase in extension from the periphery to the central region of the interface. In conclusion, Charnley cups with non-circumferential radiolucent lines and little, if any, wear can be retained without compromising the longevity of the implant. However, it should be stressed that this conclusion is based on a patient population in which four-fifths of the patients at the index operation were 65 years of age or older.

Aged↗

PubMed2001

Kinematics after tear in the anterior cruciate ligament: dynamic bilateral radiostereometric studies in 11 patients.

We studied the kinematics of both knees using radiostereometry in 11 patients with unilateral injury of the anterior cruciate ligament and normal contralateral knee. Continuous radiostereometric exposures at a speed of 24 exposures a second were performed, when the patients ascended an 8 cm high platform. The tibial center was more dorsally displaced and the tibia more externally rotated on the injured side. This increasing external tibial rotation was associated with increased anterior displacement of the lateral femoral condyle. The latter also displayed less anterior-posterior translations during continuous extension. The anterior-posterior translation of the medial condyle was about the same as on the uninjured side. Changes in the kinematics of the knee joint due to rupture of the anterior cruciate ligament can result in an abnormal joint load, which may increase the risk of damage to the cartilage and the menisci.

Adolescent↗

PubMed2001

Low effectiveness of prescribed partial weight bearing. Continuous recording of vertical loads using a new pressure-sensitive insole.

To enable objective measurements of weight bearing in hip replacement patients a portable instrument set-up with an on-line registering pressure-sensitive insole was developed. Six men and 9 women, median age 58 (48-67) years, who had been operated on with a cementless or hybrid hip arthroplasty were studied. All patients were independent and functional. A physiotherapist instructed the patients to use crutches in order to support 30% of their body weight. The patients then walked a standardized distance with crutches over five different types of terrain: level, uphill, downhill, upstairs and downstairs. The trial was repeated once. In both men and women most of the steps taken resulted in a load of >30% of body weight. None of the patients managed to comply with the directive, even though five of them thought they did. The type of terrain had no significant influence on the pattern of load. Our findings indicate that the effectiveness of prescribing limited weight bearing is questionable.

Aged↗

PubMed2000

In vivo kinematics of total knee arthroplasty: flat compared with concave tibial joint surface.

This study evaluated the influence of the geometric configuration of the tibial joint area on the kinematics of the knee. Twenty-two patients with noninflammatory arthritis and minor preoperative deformity were studied. They each received an AMK total knee replacement with retention of the posterior cruciate ligament. Eleven patients without any knee abnormalities were used as controls. The patients were stratified to either the flat (terminology of the manufacturer: standard) or concave (terminology of the manufacturer: constrained) polyethylene insert (n = 11 in each group). Knee kinematics were assessed 1 year after the operation by having the patient ascend a platform corresponding to an extension of the knee from 50 to 70 degrees of flexion. During this motion, two film-exchangers simultaneously exposed six to 13 pairs of serial stereoradiographs. The concave geometric configuration of the tibial insert resulted paradoxically in increased anterior-posterior translations compared with the flat insert but no significant change of rotations and translations in the other directions. Compared with normal knees, the most obvious abnormality was increased anterior-posterior translations (p < 0.004). At 50 degrees of flexion, the implants with the flat tibial polyethylene insert had displaced 2 times and the concave ones had displaced 2.5 times more posteriorly than the normal knees (p < or = 0.001). Less internal tibial rotation was also recorded in the flexed positions for both types of inserts compared with the normal knees (p < 0.02). Four knees in four patients, who reported symptoms of instability and abnormal knee function, showed significantly increased proximal displacement of the center of the tibial plateau in the flexed position. The findings suggest that current prosthetic designs and surgical technique do not restore normal knee kinematics and indicate that design improvements should rely on in vivo kinematic studies.

Aged↗

PubMed2000

Outcome scores in degenerative cervical disc surgery.

Forty-six consecutive patients with neck pain and arm radiculopathy were treated with anterior cervical discectomy and fusion. All patients had neurological symptoms corresponding to a herniated disc and/or spondylosis at one or two cervical levels, verified by magnetic resonance imaging. The patients were stabilized with an anterior graft and randomized to either fixation with a CSLP plate or no internal fixation. Preoperatively and 2 years postoperatively the patients filled in a questionnaire that included a modified Million Index, a modified Oswestry Index and the Zung Depression Scale. They were also asked to register their pain in the arm and in the neck on a vertical visual analogue scale (VAS). At the 2-year follow-up, an unbiased observer graded the patients' clinical outcome using Odom's criteria. A test-retest procedure was carried out to examine the questionnaire reproducibility. In the group that was operated at one level, there was no significant improvement in any of the scores. Nevertheless, 81% of the patients were satisfied with the outcome of the surgery. All scores improved in the group operated at two levels. The pain in the neck and arm, as measured on a VAS, decreased in both groups. The improvement in arm pain was significantly more pronounced in patients operated with a plate at two levels compared to those who were operated without a plate. At the 2-year follow-up, patients with an excellent or good result according to Odom's criteria had a lower Million Index (P < 0.0005), Oswestry Index (P < 0.0005), and Zung (P = 0.024) score, than the group classified as fair or poor. There was a significant correlation (P < 0.0001 for all scores) between the test and retest results. We conclude that the modified Million Index and Oswestry Index are clinically useful tools in the evaluation of outcome after degenerative cervical disc surgery. The clinical benefits of plate fixation were minimal. The outcome after surgery, measured with the Oswestry Index, Million Index and VAS for arm and neck pain, seems to correlate well with the classification of outcome by Odom.

Adult↗