Lymphatic transport from normal and synovitic knees in rabbits

The resorption pattern of synovial fluid through the lymphatic system from normal and synovitic knee joints in rabbits was studied with 99mtechnetium-rhenium-sulfur colloid injected intraarticularly and monitored for 14 hours with a gamma camera. On the normal side the regional lymph nodes were visualized after 1 hour and after 14 hours still 75 percent activity remained in the knee. In the synovitic knees no lymphatic transport could be detected; and the radiotracer was unstable with rapid liberation of technetium, which was excreted in the urine. This radiolysis was not found in vitro in synovitic joint fluid. The lymphatic transport from normal rabbit knees is low. We found a clear difference in lymphatic transport between normal and synovitic knee joints.     

Resorption of intraarticular diffusible and microcolloid tracers. Rabbit studies of normal and synovitic knees

The resorption of two radiotracers (99mtechnetium-labeled microcolloid particles to study lymphatic transport and 51 chromium-EDTA to study diffusion) from the knee joint and the subcutaneous tissue of rabbits was investigated simultaneously. In 12 rabbits, synovitis was induced in the right knee 6 weeks or 3 months before the investigation; 6 rabbits served as controls. The final number of Tc-particles in the normal knees and in the subcutaneous tissue in the three groups did not differ; but removal from the synovitic knees was increased. The final number of Cr-EDTA particles did not differ within or between groups. The initial decrease was highest in the knees with acute synovitis (P less than 0.05). The results indicate (1) that in synovial tissue lymphatic transport is of little importance, (2) that leakage through the synovial membrane increases in synovitis, and (3) that a subcutaneous depot can be used as a reference instead of injections into a normal knee.     

Insufficient recovery of neuromuscular activity around the knee after experimental anterior cruciate ligament reconstruction

Background Operative and nonoperative treatment of anterior cruciate ligament (ACL) injuries is often associated with a lack of proprioception and persistent muscle weakness of unknown origin.

Methods This long-term study in the cat experimentally compares both neural and muscular activity in the articular nerves of the knee (PAN and MAN), quadriceps and hamstrings, in the chronic unstable knee, and in the reconstructed knee. We also investigated changes in neuromuscular response due to the mechanical competence of the graft, comparing stable and unstable reconstructed knees.

Results We found increased periarticular muscle activity during anterior tibial translation in chronically unstable knees. Both reconstructed and non-reconstructed knees lost fast reactive activity in the articular nerves. When stability was recovered after reconstruction, the knees showed a more adjusted—although incomplete—muscular reaction.

Interpretation ACL-injured knees in the cat, with or without reconstruction, show definite abnormalities in neuromuscular reaction in the long term. Regaining stability with a competent graft in the reconstructed knee is crucial for reduction of this anomalous reaction.     

Tensile properties of the knee-joint capsule at an elevated intraarticular pressure

In order to evaluate the capsular reaction to high intraarticular pressure (IAP) in the knee during arthroscopy, we examined 13 patients admitted for elective surgery with joint infusion to 30, 70, 120 and 170 mmHg IAP (4, 9.3, 16 and 22.7 kPa). The infusion was repeated once, at all IAP levels except 30 mmHg, after 2 min and was recorded for another 2 min. A pressure-time curve was recorded as a combined effect of viscoelastic properties of the capsule and extraarticular fluid absorption. 3 more knee joints were infused directly to 170 mmHg and a pressure-time curve was recorded for 15 min, after which time the joint was reinfused to 170 mmHg in order to estimate the change in joint volume due to absorption or relaxation.

In 10 knees, the curves were uniform. At infusion, the pressure curve was almost linear above 70 mmHg. There were no signs of plastic deformation of the joint capsule at pressures below 120 mmHg, while at 170 mmHg there were signs of capsular deformation. At each pressure level, the curve revealed a rapid fall in initial pressure that gradually decreased because of capsular relaxation or fluid absorption. Repeated infusion delayed the fall in pressure, due to increased capsular stiffness.

In 3 knees infused directly to 170 mmHg IAP, the slope for the first 2 min of the pressure-time curve did not differ from that found at maximal IAP in knees examined with stepwise increasing pressures. Discontinuity of the capsule, even of puncture size, influenced the pressure/volume correlation considerably.

We conclude that at IAP levels of 170 mmHg, there are signs of plastic deformation of the joint capsule. In order to avoid capsular damage, knee arthroscopy should be done at intraarticular pressure levels below 120 mmHg.     

Joint Changes after Overuse and Peak Overloading of Rabbit Knees In Vivo

The effect of overuse and overuse combined with axial peak overloading on the knee joints of living rabbits has been investigated. A specially constructed apparatus was used for this purpose. Physical and biochemical changes are reported and include:

1. Early and progressive damage to the articular cartilage surface shown by the scanning electron microscope.

2. The presence of an increased amount of prostaglandin E in the synovial fluid.

3. A reduction of cyclic 3'-5' adenosine monophosphate in the subchondral bone.

4. Late changes which were consistent with osteoarthritis.

These changes were found only in the joints subjected to simultaneous overuse and peak overloading.

The results suggest that:

1. Cartilage damage and chemical changes in the subchondral bone are simultaneous and are both responsible for eventual degenerative changes.

2. Frictional overuse alone does not seem to be responsible for the production of osteoarthritis.     

Serum Concentrations of Tobramycin® After Intraarticular Administration: An Experimental Study in the Rabbit

Serum concentration of the aminoglycoside tobramycin was followed for 120 min after intraarticular injection of 20 mg tobramycin in six rabbit knee joints.

Highest concentration was observed after 15-30 min, and compared with the values after intramuscular injection the serum half life was equal. No pathological changes were observed by histological examination of the synovial membrane and articular cartilage.

It was concluded that no damage of the joint has been demonstrated after intraarticular injection of tobramycin, but the serum concentration must be monitored due to the rapid transport from the joint cavity.     

Chondromalacia induced by patellar subluxation in the rabbit

A unilateral patellar malalignment was induced in 20 young and 20 mature rabbits by lateral displacement of the tibial tuberosity, the other knee serving as osteotomized in situ control.

At 6 weeks, all the knees appeared macroscopically normal, but histologically definite cartilage degeneration was found on the experimental side. At 3 months, macroscopic changes occurred in 5 of 10 mature rabbits, and histologic cartilage degeneration was found in all the experimental knees, most pronounced in mature animals, and particularly in joint facets submitted to high pressure.

This experimental model produces changes resembling chondromalacia patellae and early arthrotic changes suggesting the importance of malalignment in the development of patellofemoral cartilage degeneration.     

Meniscus repair in knee ligament injuries

One hundred and fifteen primarily operated patients with medial collateral ligament tears of the knee have been reviewed. Two-thirds of the patients had associated cruciate ligament injuries.

In 59 knees, injuries of the medial meniscus were found. Suture of the medial meniscus was performed in 53 patients, while medial meniscectomy was done in only six cases.

Knee function was evaluated by follow-up after 4 (2-8) years. Excellent or good results as evaluated by the Lysholm knee score were obtained in 86 per cent of the patients, with equally good results in those with meniscus suture as compared to those without meniscus injury. No secondary men-iscectomies were performed.     

Hemodynamics of the Juvenile Knee in Relation to Increasing Intra-Articular Pressure: An Experimental Study in Dogs

The relationships between intraosseous pressure and regional blood flow in the juxta-articular epiphyses were determined in the knees of immature dogs. Intraosseous pressures were continously registered in one knee. Regional blood flow rates were simultaneously determined by the microsphere technique before and after venous tamponade of both knee joint capsules.

During complete venous tamponade the intraosseous pressure of the distal femoral epiphyses rose 268%, while flow increased 122%. A concurrent 20-fold flow increase of the knee capsule and 3-4-fold flow increase of the proximal femoral bone was observed. Evacuation of the knee joints resulted in an immediate drop of the intraosseous pressure of the distal femoral epiphyses, whereas hyperaemia prevailed for at least half an hour and was most pronounced in the distal femoral epiphyses and knee joint capsule. Intraosseous pressure registration did not significantly influence regional blood flow.

It is suggested that the changes of intraosseous pressures during knee joint tamponade reflect changes in the venous outlet resistance. The results demonstrate the significance of intra-articular pressure increase on the hemodynamics of the juxta-articular tissues of the knee and proximal femoral bone. These findings may be of importance in the pathogenesis of growth disturbances observed in juvenile degenerative arthritis.     

Treatment of the exposed knee prosthesis

Ten knees with early tissue breakdown after knee arthroplasty resulting in exposed prostheses were treated with different plastic surgical techniques. Six knees were successfully covered: four using a gastrocnemius musculocutaneous flap, one using a fasciocutaneous flap, and one using split-skin grafts. Four knees failed: two using local skin flaps and two using split-skin grafts.

A gastrocnemius musculocutaneous flap seems to provide a reliable coverage of the exposed knee joint.     

Scintigraphy in the assessment of anterior knee pain

Sixty knees presenting with chronic anterior pain were investigated. A diffusely increased uptake indicated sympathetically mediated pain provided other diagnoses such as synovitis or widespread arthrosis were excluded. Focal uptake was not specific to any one condition, but could occur in chondromalacia patellae or recent dislocations. However, the commonest appearance found in chondromalacia patellae was a normal scan. A characteristic scintigraphic appearance in symptomatic postpatellectomy knees, which has not been previously reported, was increased uptake in the femoral groove. In all the cases where no clinical or arthroscopic diagnosis was made, the bone scan was normal.

The use of radioisotope scintigraphy is recommended in the problem knee presenting with anterior pain.     

Cemented tibial component fixation performs better than cementless fixation: a randomized radiostereometric study comparing porous-coated, hydroxyapatite-coated and cemented tibial components over 5 years

Background The question whether the tibial component of a total knee arthroplasty should be fixed to bone with or without bone cement has not yet been definitely answered. We studied movements between the tibial component and bone by radiostereometry (RSA) in total knee replacement (TKR) for 3 different types of fixation: cemented fixation (C-F), uncemented porous fixation (UC-F) and uncemented porous hydroxyapatite fixation (UCHA-F).

Patients 116 patients with osteoarthrosis, who had 146 TKRs, were included in 2 randomized series. The first series included 86 unilateral TKRs stratified into 1 of the 3 types of fixation. The second series included 30 patients who had simultaneous bilateral TKR surgery, and who were stratified into 3 subgroups of pairwise comparisons of the 3 types of fixation.

Results After 5 years 2 knees had been revised, neither of which were due to loosening. 1 UCHA-F knee in the unilateral series showed a large and continuous migration and a poor clinical result, and is a pending failure. The C-F knees rotated and migrated less than UC-F and UCHA-F knees over 5 years. UCHA-F migrated less than UC-F after 1 year.

Interpretation Cementing of the tibial component offers more stable bone-implant contact for 5 years compared to uncemented fixation. When using uncemented components, however, there is evidence that augmenting a porous surface with hydroxyapatite may mean less motion between implant and bone after the initial postoperative year.     

The Attenborough Total Knee Prosthesis: Results of 25 Operations Evaluated According to Two Different Assessment Systems

The Attenborough stabilized gliding total knee prosthesis was used in cases of severely damaged, highly unstable or deformed knees. Twenty-five operated cases were followed for 1 1/2 years (range 12-28 months).

The results were assessed according to two different knee evaluation systems: The Lotke & Ecker knee evaluation index and the knee function assessment chart (BOA chart) suggested by the British Orthopaedic Association. The overall results were excellent or good in 84 per cent (21/25) of the cases according to both systems, but when considering the improvement in individual clinical features the BOA chart results were more optimistic. Neither of the systems takes into consideration that the results are influenced by possible disorders in other joints. If only the function of the knees was being judged the results of the operations with the Attenborough prosthesis were excellent or good in 96 per cent (24/25) in this series In general the results were found to be as good as those obtained in less disabled knees treated with compartmental prostheses. As more extensive surgery and bone resection is needed for insertion of the Attenborough prosthesis compared with compartmental prostheses, its use should be restricted to severely damaged knees which would otherwise be treated with a hinged prosthesis or an arthrodesis.     

Joint position sense is not changed after acute disruption of the anterior cruciate ligament

We evaluated the impact of acute, isolated ACL disruption on knee joint proprioception by means of passive-active and active-active joint position sense (JPS) measurement techniques. 18 subjects with acute, isolated and unilateral ACL disruption were tested for JPS in a standing position. The test protocol included 6 trials for each leg. In each trial, the lower leg was passively positioned to an index angle approximating either 30° or 70°, followed by 5 active repetitions of the index angle where the subjects attempted to reproduce the index angle to the best of their ability.

The errors from the exact index angle reproduction were calculated as both real (showing both magnitude and direction) and absolute values (only magnitude). All subjects had a tendency to reproduce the index angle with both the injured and normal knees in a more flexed position (overestimation). Only the absolute error produced by the active-active test at flexion angles greater than 45° produced a significant difference with a larger error for the normal knee. In all other comparisons between the injured and the normal knee no differences were found.

We conclude that the afferent signals which are compromised by an acute tear of the ACL are insignificant compared to afferent signals from the other joint and muscle receptors.     

Septic arthritis of the knee: Five cases treated with synovectomy

Five cases of suppurative non-gonococcal arthritis of the knee were treated with synovectomy 1-2 weeks after the diagnoses were confirmed. Indications for operation were persistent fever and continuous effusion, in spite of adequate antibiotic treatment and serial needle aspirations.

The infection subsided in all cases. At follow-up, 2 years after operation, one patient had died of other disease, and there had been no recurrences among the remaining four. One patient had disabling pain on weight-bearing and considerable restriction of knee motion with 2-3 mm radiographic narrowing of the joint space. Three knees were painless on normal motion, but in two cases changes resembling osteochondritis were found radiographically.     

All-polyethylene vs. metal-backed tibial component in total knee arthroplasty-a randomized RSA study comparing early fixation of horizontally and completely cemented tibial components: part 2. Completely cemented components: MB not superior to AP components

Background Uncertainty exists as to whether metal backing (MB) of the tibial component is better than an all-polyethylene component (AP). This is valid for both horizontally and completely cemented components. We evaluated completely cemented MB vs. AP (Part 2).

Patients and methods In a randomized study, 39 patients (40 knees) with knee arthrosis were operated with cemented low-conforming total knee arthroplasty (AGC, Biomet) with a tibial component of uniform thickness (8 mm), cemented both beneath the tibial tray and around the stem. 20 patients had an all-polyethylene (AP) tibial component and 20 patients had an identical but metal-backed (MB) tibial component. We used clinical examination and radiostereometric analysis (RSA) to evaluate the hypothesis that MB improves component fixation. Fixation was evaluated using RSA up to 2 years after surgery. Clinical assessment was performed preoperatively and after 2 years using the Hospital for Special Surgeons (HSS) score.

Results We found no differences in micromotion, and no differences in clinical scores could be detected between the groups at any time point.

Interpretation Our findings indicate that there was equal initial fixation of the AP and MB stemmed monobloc components when they were cemented beneath the tibial plateau and around the stem.

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Popliteal Cysts (Baker's Cysts) in Adults: I. Clinical and Roentgenological Results of Operative Excision

Forty patients were re-examined between 6 months and 15 years (mean 4 years) after excision of a popliteal cyst. Forty-six operations had been performed, including one bilateral cyst and five recurrent cysts. The history was reviewed with respect to the preoperative symptoms, clinical and roentgenological signs, the operative and histopathological findings and the postoperative course. Fifteen operations were followed by wound healing complications or tense swelling of the calf simulating deep venous thrombosis. At clinical follow-up a recurrent cyst was found in 63 per cent of the knees. A simplified follow-up arthrography was performed in all knees, and revealed a cyst-like cavity in all but one knee. The majority of the recurrent cysts displayed irregularities of the wall that had not been seen in the preoperative arthrograms.

Despite this high rate of recurrence most of the patients had fewer symptoms from the popliteal space at the time of follow-up than before the operation.

As associated knee disorders were present in the majority of patients, popliteal cysts (Baker's cysts) should be regarded and, if possible, treated as secondary to the basic pathological condition of the joint. Only if the knee disorder is not curable and if the symptoms from the popliteal region are troublesome should excision of the cyst and tight closure of the communication with the joint be considered.     

Impulse-forces during walking are not increased in patients with knee osteoarthritis

Background Impulsive forces in the knee joint have been suspected to be a co-factor in the development and progression of knee osteoarthritis. We thus evaluated the impulsive sagittal ground reaction forces (iGRF), shock waves and lower extremity joint kinematics at heel strike during walking in knee osteoarthritis (OA) patients and compared them to those in healthy subjects.

Subjects and methods We studied 9 OA patients and 10 healthy subjects using three-dimensional gait analyses concentrated on the heel strike. Impulse GRF (iGRF) was measured together with peak accelerations (PA) at the tibial tuberosity and sacrum. Sagittal lower extremity joint angles at heel strike were extracted from the gait analyses. As OA is painful and pain might alter movement strategies, the patient group was also evaluated following pain relief by intraarticular lidocaine injections.

Results The two groups showed similar iGRF, similar tibial and sacral PA, and similar joint angles at heel strike. Following pain relief, the OA patients struck the ground with more extended hip and knee joints and lower tibial PA compared to the painful condition. Although such changes occurred after pain relief, all parameters were within their normal ranges.

Interpretation OA patients and healthy subjects show similar impulse-forces and joint kinematics at heel strike. Following pain relief in the patient group, changes in tibial PA and in hip and knee joint angles were observed but these were still within the normal range. Our findings make us question the hypothesis that impulse-forces generated at heel strike during walking contribute to progression of OA.     

Outcome of isolated tibial polyethylene insert exchange after uncemented total knee arthroplasty: 27 patients followed for 8-71 months

Background The outcome of performing isolated tibial polyethylene insert exchange (ITPIE) after total knee arthroplasty (TKA) is under debate. We evaluated the survival probability of ITPE after uncemented TKA.

Method 27 patients (27 knees) with an ITPIE performed mean 9 (0.9-17) years after the initial TKA were included in the study (22 patients also had the patellar component replaced simultaneously). All patients had their exchange performed at our department between 1997 and 2001 and had their latest follow-up examination mean 40 (8-71) months after the exchange.

Results During the follow-up, 2 patients had total knee revision because of aseptic loosening and 2 patients had isolated patella component exchange (in 1 of the patients, combined with a new ITPIE). Kaplan-Meier survival analysis gave a survival probability of 80% at 34 months of follow-up.

Interpretation The short-term survival after an ITPIE was similar to that of a total knee revision with exchange of all components. Since the ITPIE is a much smaller operation with fast rehabilitation, we recommend it in elderly patients with a well-fixed and wellaligned prosthesis without surface damage of the components.     

Effect of bone marrow grafting on the titanium porous-coated implant in bilateral total knee arthroplasty

Background and purpose Poor bone ingrowth into the porous coating of tibial components has been reported. We hypothesized that iliac marrow grafting might be useful to enhance bone ingrowth into a porous-coated implant. The first part of this study was to examine the presence of fibroblast colony-forming units (CFUF) containing osteogenic precursor cells in tibial bone marrow and iliac bone marrow. The second aim was to compare the clinical and radiographic results after bilateral total knee arthroplasty (TKA) with and without autologous bone marrow transplantation to the bone-implant interface.

Methods Simultaneous bilateral TKA was performed in 21 patients with osteoarthritis. Aspirated iliac bone marrow was transplanted to the interface of one randomly selected porous-coated tibial component in each patient, and contralateral knees served as controls. All of the 21 patients were followed for 5 years.

Results The average number of CFU-F was significantly lower in tibial marrow than in iliac marrow (p = 0.008). The final fluoroscopically-guided radiographs revealed a decrease in the number of knees with radiolucent lines after marrow grafting compared to those without grafting (p = 0.004).

Interpretation Iliac bone marrow is useful as a bone grafting material to enhance the biological fixation in porous-coated implants.