Knee Capsule Research Articles

Assessing the relationship of the peroneal nerve to the posterolateral corner of the knee and influence of race on its dimensions– A MRI based study in Indian population

BackgroundThe relationship of Common peroneal nerve (CPN) to the posterolateral corner of the knee joint is important for surgeons who perform total knee arthroplasty to avoid injury to the nerve during surgery. This relationship varies among different races on account of anthropometry. This study aims to evaluate the anatomical location of this nerve in Indian patients using an MRI based reference system. Methods213 knee magnetic resonance images (MRIs) were evaluated in axial plane 8 mm below the joint line for distance of the CPN from the closest posterolateral capsule. The angle of the CPN from the center of the tibial anteroposterior axis and relation of CPN with respect to the popliteus were evaluated. A comparative analysis of these measurements among Caucasian, Chinese and Indian patients was made to evaluate for any differences. ResultsThe mean distance between the CPN and the knee capsule was 15.55 mm (range, 7.8–26.2 mm). The mean angle of the CPN from the center of the AP axis was 50.1° (range, 38–63). CPN was found to be in line with the popliteus from center of the knee in 62% cases. There was no significant difference among the different races among the measured parameters (p > 0.005). ConclusionThis study establishes a “danger zone” and a “safe zone” to avoid CPN injury in total knee arthroplasty in Indian patients and identifies anatomic landmarks to localize the nerve before the soft-tissues release in order to avoid direct injury.

Femoral nerve catheter vs local infiltration for analgesia in fast track total knee arthroplasty: short-term and long-term outcomes

BackgroundThe aim was to compare the effects on short-term and long-term pain and functional outcome of periarticular local anaesthetic infiltration (LIA) with LIA of the posterior knee capsule in combination with a femoral nerve block (FNB) catheter in patients undergoing total knee arthroplasty. MethodsEighty patients were randomised to one of two groups: Subjects in group LIA received periarticular LIA with ropivacaine 0.2% for postoperative analgesia; subjects in group FNB received LIA of the posterior capsule and a FNB catheter. The primary outcome parameter was functional capacity of the knee 12 months after surgery. Secondary parameters included mobility as determined by accelerometer data, pain, satisfaction with the analgesic regimen, hospital length of stay, and use of pain medication 3 and 12 months after surgery. ResultsThere were no differences between groups in long-term functional capacity, patient satisfaction and hospital length of stay. In the first 2 days, subjects in group FNB had slightly lower pain scores and used less opioids, and subjects in group LIA had a higher level of accelerometer activity. Three and 12 months after surgery, subjects in group FNB had lower maximum pain scores and were less likely to use any pain medication 12 months after surgery. ConclusionsBoth techniques were similar regarding long-term functional outcome. Subjects in group FNB had slightly lower pain scores and lower opioid consumption after operation, lower maximum pain scores at 3 and 12 months, and were less likely to use any pain medication at 12 months. Clinical trial registrationNCT01966263.

In vivo formation of stable hyaline cartilage by transplantation of naive human bone marrow stromal cells

Purpose: Osteoarthritic cartilage defects are unable to heal on their own and surgical approaches are often ineffective. Tissue engineering using transplantation of autologous chondrocytes is also limited. Human bone marrow stromal cells (hBMSCs, also known as bone marrow-derived mesenchymal stem cells), have been suggested as a source for cartilage reconstruction. However, studies using hBMSCs pre-differentiated into cartilage prior to transplantation failed to demonstrate formation of stable, hyaline-like cartilage that is resistant to hypertrophy in vivo. We previously determined that naive (untreated) hBMSCs were able to form stable, non-hypertrophic cartilage when transplanted subcutaneously in conjunction with fibrin microbeads covalently coated with hyaluronic acid (HyA-FMBs). In our current study, we are investigating the ability of hBMSC/HyA-FMB constructs to generate cartilage in an articular defect in immunocompromised rodents. Methods: FMB were manufactured by dehydrothermal crosslinking of concentrated thrombin activated fibrinogen emulsified in heated oil. The FMB were collected, rinsed in organic solvents and ethanol, and sieved for sizing. FMB were then coated by crosslinking HyA to their surfaces using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride. hBMSCs were cultured from orthopedic surgery bony waste and cryopreserved in liquid nitrogen. Prior to implantation in rodents, hBMSCs were thawed and incubated for 12 hours with protamine and iron oxide nanoparticles for cell tracking. Cells were then incubated in suspension with HyA-FMBs for attachment for 90 minutes. hBMSC/HyA-FMB constructs were transplanted subcutaneously into the backs of NSG immunocompromised mice using standard procedures. To create intra-articular damage, the knee capsule was accessed from a medial parapatellar incision. The patella was laterally dislocated, and the distal femur immobilized using a miniature positioning clamp. A microdrill with a 0.5mm burr was used to drill a 1.5mm deep osteochondral defect. The defect was filled with hBMSC/HyA-FMB using a 0.5mm microcurrette. The patella was relocated and the incision closed using skin adhesive. A similar defect is being created in immunocompromised SRG rats (Hera Biolabs). Mice were euthanized on day 3 (to evaluate construct integrity), at 8 weeks (to examine early cartilage formation), at 16 weeks (to assess formation of mature cartilage), and at 28 weeks (to evaluate cartilage stability). Cell integration was determined using non-decalcified cryohistology and Prussian blue staining of iron nanoparticles. Cartilage formation was assessed using H&E, toluidine blue, and immunohistochemistry of COL1, COL2, COL10. The human origin of the cells was determined by human mitochondria immunohistochemistry. Results: Subcutaneous transplants of hBMSC/HyA-FMB formed stable hyaline-like cartilage at 28 weeks. Post osteochondral defect surgery, mice had uniform defect sizing, and no visually appreciable alterations in activity. Repair construct integrity, as assessed by cryohistology at 3 days, showed intact FMB with adherent hBMSCs visualized by Prussian Blue staining; growth of fibrous tissue was also detected. Intra-articular defect studies using larger cohorts of rodents and longer-term time points are currently underway. Conclusions: hBMSC/HyA-FMB constructs formed stable hyaline cartilage in a subcutaneous model in vivo. These data suggest that these constructs may be a viable method for repairing osteochondral defects. Further intra-articular experimentation is underway for clinical translation of this methodology.

A Comprehensive Reanalysis of the Distal Iliotibial Band: Quantitative Anatomy, Radiographic Markers, and Biomechanical Properties

Background: The qualitative anatomy of the distal iliotibial band (ITB) has previously been described. However, a comprehensive characterization of the quantitative anatomic, radiographic, and biomechanical properties of the Kaplan fibers of the deep distal ITB has not yet been established. It is paramount to delineate these characteristics to fully understand the distal ITB’s contribution to rotational knee stability. Purpose/Hypothesis: There were 2 distinct purposes for this study: (1) to perform a quantitative anatomic and radiographic evaluation of the distal ITB’s attachment sites and their relationships to pertinent osseous and soft tissue landmarks, and (2) to quantify the biomechanical properties of the deep (Kaplan) fibers of the distal ITB. It was hypothesized that the distal ITB has definable parameters concerning its anatomic attachments and consistent relationships to surgically pertinent landmarks with correlating plain radiographic findings. In addition, it was hypothesized that the biomechanical properties of the Kaplan fibers would support their role as important restraints against internal rotation. Study Design: Descriptive laboratory study. Methods: Ten nonpaired, fresh-frozen human cadaveric knees (mean age, 61.1 years; range, 54-65 years) were dissected for anatomic and radiographic purposes. A coordinate measuring device quantified the attachment areas of the distal ITB to the distal femur, patella, and proximal tibia and their relationships to pertinent bony landmarks. A radiographic analysis was performed by inserting pins into the attachment sites of relevant anatomic structures to assess their location relative to pertinent bony landmarks with fluoroscopic guidance. A further biomechanical assessment of 10 cadaveric knees quantified the load to failure and stiffness of the Kaplan fibers’ insertion on the distal femur after a preconditioning protocol. Results: Two separate deep (Kaplan) fiber bundles were identified with attachments to 2 newly identified femoral bony prominences (ridges). The proximal and distal bundles inserted on the distal femur 53.6 mm (95% CI, 50.7-56.6 mm) and 31.4 mm (95% CI, 27.3-35.5 mm) proximal to the lateral epicondyle, respectively. The centers of the bundle insertions were 22.5 mm (95% CI, 19.1-25.9 mm) apart. The total insertion area of the distal ITB on the proximal tibia was 429.1 mm2 (95% CI, 349.2-509.1 mm2). A distinct capsulo-osseous layer of the distal ITB was also identified that was intimately related to the lateral knee capsule. Its origin was in close proximity to the lateral gastrocnemius tubercle, and it inserted on the proximal tibia at the lateral tibial tubercle between the fibular head and the Gerdy tubercle. Radiographic analysis supported the quantitative anatomic findings. The mean maximum load during pull-to-failure testing was 71.3 N (95% CI, 41.2-101.4 N) and 170.2 N (95% CI, 123.6-216.8 N) for the proximal and distal Kaplan bundles, respectively. Conclusion: The most important finding of this study was that 2 distinct deep bundles (Kaplan fibers) of the distal ITB were identified. Each bundle of the deep layer of the ITB was associated with a newly identified distinct bony ridge. Radiographic analysis confirmed the measurements previously recorded and established reproducible landmarks for the newly described structures. Biomechanical testing revealed that the Kaplan fibers had a strong attachment to the distal femur, thereby supporting a role in rotational knee stability. Clinical Relevance: The identification of 2 distinct deep fiber (Kaplan) attachments clarifies the function of the ITB more definitively. The results also support the role of the ITB in rotatory knee stability because of the fibers’ vectors and their identified maximum loads. These findings provide the anatomic and biomechanical foundation needed for the development of reconstruction or repair techniques to anatomically address these deficiencies in knee ligament injuries.

To compare effect of combined block of adductor canal block (ACB) with IPACK (Interspace between the Popliteal Artery and the Capsule of the posterior Knee) and adductor canal block (ACB) alone on Total knee replacement in immediate postoperative rehabilitation

To compare effect of combined block of adductor canal block (ACB) with IPACK (Interspace between the Popliteal Artery and the Capsule of the posterior Knee) and adductor canal block (ACB) alone on Total knee replacement in immediate postoperative rehabilitation

The Anterolateral Ligament Has Similar Biomechanical and Histologic Properties to the Inferior Glenohumeral Ligament

To characterize the tensile and histologic properties of the anterolateral ligament (ALL), inferior glenohumeral ligament (IGHL), and knee capsule. Standardized samples of the ALL (n= 19), anterolateral knee capsule (n=15), and IGHL (n= 13) were isolated from fresh-frozen human cadavers for uniaxial tensile testing to failure. An additional 6 samples of the ALL, capsule, and IGHL were procured for histologic analysis and determination of elastin content. All investigated mechanical properties were significantly greater for both the ALL and IGHL when compared with capsular tissue. In contrast, no significant differences between the ALL and IGHL were found for any property. The elastic modulus of ALL and IGHL samples was 174 ± 92MPa and 139 ± 60MPa, respectively, compared with 62 ± 30MPa for the capsule (P= .001). Ultimate stress was significantly lower (P < .001) for the capsule, at 13.4±7.7MPa, relative to the ALL and IGHL, at 46.4 ± 20.1MPa and 38.7 ± 16.3MPa, respectively. The ultimate strain at failure was 37.8% ± 7.9% for the ALL and 39.5% ± 9.4% for the IGHL; this was significantly greater (P= .041 and P=.02, respectively) for both relative to the capsule, at 32.6% ± 8.4%. The strain energy density was 7.8 ± 3.1MPa for the ALL, 2.1 ± 1.3MPa for the capsule, and 7.1 ± 3.1MPa for the IGHL (P < .001). The ALL and IGHL consisted ofcollagen bundles aligned in a parallel manner, containing elastin bundles, which was in contrast to the random collagenarchitecture noted in capsule samples. The ALL has similar tensile and histologic properties totheIGHL. The tensile properties of the ALL are significantly greater than those observed in the knee capsule. CLINICALRELEVANCE: The ALL is not just a thickening of capsular tissue and should be considered a distinct ligamentous structure comparable to the IGHL in the shoulder. The tensile behavior of the ALL is similar to the IGHL, and treatment strategies should take this into account.

Anatomic and Histological Investigation of the Anterolateral Capsular Complex in the Fetal Knee

Background: There is currently disagreement with regard to the presence of a distinct ligament in the anterolateral capsular complex of the knee and its role in the pivot-shift mechanism and rotatory laxity of the knee. Purpose: To investigate the anatomic and histological properties of the anterolateral capsular complex of the fetal knee to determine whether there exists a distinct ligamentous structure running from the lateral femoral epicondyle inserting into the anterolateral tibia. Study Design: Descriptive laboratory study. Methods: Twenty-one unpaired, fresh fetal lower limbs, gestational age 18 to 22 weeks, were used for anatomic investigation. Two experienced orthopaedic surgeons performed the anatomic dissection using loupes (magnification ×3.5). Attention was focused on the anterolateral and lateral structures of the knee. After the skin and superficial fascia were removed, the iliotibial band was carefully separated from underlying structures. The anterolateral capsule was then examined under internal and external rotation and varus-valgus manual loading and at different knee flexion angles for the presence of any ligamentous structures. Eight additional unpaired, fetal lower limbs, gestational age 11 to 23 weeks, were used for histological analysis. Results: This study was not able to prove the presence of a distinct capsular or extracapsular ligamentous structure in the anterolateral capsular complex area. The presence of the fibular collateral ligament, a distal attachment of the biceps femoris, the entire lateral capsule, the iliotibial band, and the popliteus tendon in the anterolateral and lateral area of the knee was confirmed in all the samples. Histological analysis of the anterolateral capsule revealed a loose, hypocellular connective tissue with less organized collagen fibers compared with ligament and tendinous structures. Conclusion: The main finding of this study was that the presence of a distinct ligamentous structure in the anterolateral complex is not supported from a developmental point of view, while all other anatomic structures were present. Clinical Relevance: The inability to prove the existence of a distinct ligamentous structure, called the anterolateral ligament, in the anterolateral knee capsule may indicate that the other components of the anterolateral complex, such as the lateral capsule, the iliotibial band, and its capsule-osseous layer, are more important for knee rotatory stability.

The Transseptal Arthroscopic Knee Portal Is in Close Proximity to the Popliteal Artery: A Cadaveric Study.

The purpose of this study was to use fluoroscopy to measure the distance between the transseptal portal and the popliteal artery under arthroscopic conditions with an intact posterior knee capsule, and to determine the difference between 90 degrees of knee flexion and full extension. The popliteal artery of eight fresh-frozen cadaveric knees was dissected and cannulated proximal to the knee joint. The posterolateral, posteromedial, and transseptal portals were then established at 90 degrees of flexion. A 4-mm switching stick was placed through the transseptal portal, and barium contrast was injected into the popliteal artery. A lateral fluoroscopic image was taken with the knee in 90 degrees of flexion and full extension, and the distance between the popliteal artery and the switching stick was measured and compared using a paired t-test. In knee flexion, the average distance between the transseptal portal and the anterior aspect of the popliteal artery for the eight cadaveric specimens was 12.0 mm ± 3.3 mm; in extension, this decreased to 9.0 mm ± 2.7 mm. The distance between the transseptal portal and popliteal artery was significantly higher at 90 degrees of knee flexion as compared with extension (p = 0.0005). The transseptal posterior knee arthroscopic portal must be carefully created due to the close proximity to the popliteal artery, and may be closer to the artery than previously reported in specimens with an intact posterior knee capsule. Creating the portal with the knee in flexion significantly displaces the popliteal artery away from the portal reducing the risk of arterial injury.

Novel Spiked-Washer Repair Is Biomechanically Superior to Suture and Bone Tunnels for Arcuate Fracture Repair.

Injuries to the posterolateral corner of the knee can lead to chronic degenerative changes, external rotation instability, and varus instability if not repaired adequately. A proximal fibula avulsion fracture, referred to as an arcuate fracture, has been described in the literature, but a definitive repair technique has yet to be described. The objective of this study was to present a novel arcuate fracture repair technique, using a spiked-washer with an intramedullary screw, and to compare its biomechanical integrity to a previously described suture and bone tunnel method. Ten fresh-frozen cadaveric knees underwent a proximal fibula osteotomy to simulate a proximal fibula avulsion fracture. The lateral knee capsule and posterior cruciate ligament were also sectioned to create maximal varus instability. Five fibulas were repaired using a novel spiked-washer technique and the other 5 were repaired using the suture and bone tunnel method. The repaired knees were subjected to a monotonic varus load using a mechanical testing system instrument until failure of the repair or associated posterolateral corner structures. Compared with the suture repair group, the spiked-washer repair group demonstrated a 100% increase in stiffness, 100% increase in yield, 110% increase in failure force, and 108% increase in energy to failure. The spiked-washer technique offers superior quasi-static biomechanical performance compared with suture repair with bone tunnels for arcuate fractures of the proximal fibula. Further clinical investigation of this technique is warranted and the results of this testing may lead to improved outcomes and patient satisfaction for proximal fibula avulsion fractures.

The ultrasound‐guided iPACK block with continuous adductor canal block for total knee arthroplasty

SummaryWe report a case of pre‐operative ultrasound‐guided local anaesthetic infiltration of the interspace between the popliteal artery and the capsule of the posterior knee (iPACK), in a 75‐year‐old male undergoing total knee arthroplasty. This was supplemented with postoperative adductor canal block using a continuous catheter technique. We assessed postoperative analgesia at rest and during active flexion of the knee, opioid consumption, motor and functional recovery, and patient satisfaction, for three postoperative days. This technique provided effective motor‐sparing analgesia, and was associated with excellent patient satisfaction.

Uncommon Cause of Knee Pain in Behçet’s Disease: Suprapatellar Synovial Chondromatosis

A 44-year-old male patient with Behcet’s disease presented to our clinic with progressively worsening right knee pain and suprapatellar swelling. The knee pain started about a month previously and increased over time. The characteristic of the pain was mechanical. He did not feel pain while sleeping. Previously, he had received analgesic medications but there had been no significant improvement. There was no pain in any other joint, and there was no history of disease or trauma and arthritis attack associated with the knee. The patient had a history of Behcet’s disease for five years and patient was using colchicine 3x1 pozology a day. On physical examination there was no arthritis findings. Patella shock test was negative. The patient was seen to have visibly swollen suprapatellar area. On palpation the swelling was hard, non-mobile, well defined, and measured 2x1 cm. Radiography of the knee indicated multiple soft tissue calcifications outside the joint capsule of the right knee. Knee magnetic resonance imaging revealed expanded sinovium that contained osteochondromas, which were hypointense all sequences (Figure 1). The patient’s blood tests were normal. Arthroscopic debridement were performed with symptomatic right knee joint. Pathology results were evaluated as synovial chondromatosis (SC). SC is a rare arthropathy of unknown etiology. The disease is generally monoarticular, usually occurs unilaterally in the large joints like the knee, hip, and elbow (1). Primary or idiopathic form may occur in an otherwise normal joint, but secondary SOC may occur due to trauma or degenerative diseases. On the other hand, it may occur in the setting of preexistent osteoarthritis, rheumatoid arthritis, osteonecrosis, osteochondritis dissecans, neuropathic osteoarthropathy, tuberculosis, or osteochondral fractures (2,3). To the best of our knowledge, the suprapatellar SOC of the knee in a Behcet disease is rare, and this encouraged us to report this case. Secondary SC should be included in the differential diagnosis of Behcet disease’s joint pain.

A Cause of Protrusio Acetabuli: Hip Joint Synovial Chondromatosis

A 60-year-old male patient presented to our clinic with pain, loss of range of motion in right hip and difficulty in walking. The pain started about 3 months previously and increased over time. Hip pain spreading to the trochanteric region of the right hip. The characteristic of the pain was mechanical. He did not feel pain while sleeping. Prolonged sitting or standing caused the hip to lock. Previously, he had received analgesic medications but there had been no significant improvement. There was no history of trauma. Physical examination revealed an antalgic gait and the motion of the right hip joint was limited and painful in all directions, whereas lumbar and left hip joint motions were unrestricted and painless. There were no neurological deficits of the lower extremities. Radiography of the pelvis indicated a narrowing joint space, and there were erosions on acetabular side of the joint and multiple soft tissue calcifications outside the joint capsule of the right knee. Magnetic resonance imaging of the right hip revealed findings consistent with synovial chondromatosis, which filled the joint space completely which was hypointense and acetabular protrusion progressing secondarily to synovial chondromatosis (Figure 1). Serological and biochemical markers and ultrasound of the inguinal region were normal. The patient was diagnosed with protrusio acetabuli in hip joint caused by synovial chondromatosis. Arthroscopic debridement were performed with symptomatic right hip. The aim of presenting this case was to demonstrate that hip joint synovial chondromatosis which are not directly involved in etiological factors can cause secondary protrusio acetabuli. Protrusio acetabuli is identified with an acetabular line projecting ilioischial line for 3 mm in males and 6 mm in females on antero-posterior radiographs of the pelvis. The gradual deepening of the acetabular cavity is caused by primary idiopathic and secondary neoplastic, infectious, metabolic, inflammatory, traumatic, and genetic disorders (1). This is the first case seen in the literature, despite various studies conducted about the etiology, no common factor was found. The joint replacement surgery is usually necessary in cases of severe pain or substantial joint restriction owing to secondary hip arthritis (2).

A Case Study of Baker Cysts With Intramuscular Extension into the Medial Head of the Gastrocnemius

Baker cysts are common pathological findings during sonography of the popliteal fossa. Although they can present as a typical, mild variant or have an atypical sonographic appearance, a common feature of them is that their expansion is usually limited in the intermuscular planes or spaces between muscles and knee capsule. Baker cysts extending into muscles are rare. Two cases of a Baker cyst with extension into the medial head of the gastrocnemius (MHG) are reported with sonographic findings. Both of the cases were discovered in females, who had anterior or bilateral knee pain and radiographic features of osteoarthritis. Knee effusion was identified sonographically in both of the patient cases. In the popliteal fossa, Baker cysts were found in both patients with intramuscular extension into the MHG. In the first case, a cystic penetration was noted into the MHG, near the neck of the cyst, having a cone shape and oriented toward the inferior aspect of the muscle. The second case had a cystic penetration into the MHG near the base of the cyst with a tube shape, along its long axis. The possible pathogenesis is discussed.

A Rare Co-Existing of Hip and Knee Joint’s Synovial Chondromatosis: A Case Report

A 29-year-old male patient presented to our clinic with progressively worsening bilateral hip pain, right knee pain and swelling. The hip and knee pain started about 3 months ago and increased over time. Pain of the hip joints was spreading bilaterally to the trochanteric regions. The characteristic of the pain was mechanical. He did not feel pain while sleeping. Prolonged sitting or standing caused the hip to lock. Previously, he had received analgesic medications but there had been no significant improvement. There was no pain in any other joint, and there was no history of disease or trauma associated with the hip and knee. Physical examination revealed an antalgic gait and the patient had visibly swollen right popliteal fossa. The motion of the right hip joint was limited and painful in all directions, whereas lumbar and left hip joint motions were unrestricted. He could fully extend his knee, but flexion was restricted to only 120 degrees. Radiography of the pelvis and knee indicated a narrowing joint space, and there were erosions on the acetabular side of the joint and multiple soft tissue calcifications outside the joint capsule of the right knee. Magnetic resonance imaging (MRI) of the bilateral hip revealed findings consistent with synovial chondromatosis, which filled the joint space completely and MRI of the knee revealed expanded sinovium that contained osteochondromas, which were hypointense in all sequences (Figure 1). Orthopedic surgical procedures including arthroscopic debridement were planned with symptomatic right hip and right knee joints. Synovial osteochondromatosis is a rare benign condition characterized by the formation of multiple nodules of hyaline cartilage within the sub-synovial connective tissue (1). The condition is generally monoarticular and involves the knee in more than 50% of the cases (2). The other common joints involved are hip, elbow, shoulder and ankle. In the literature, Kose et al. (3) presented a unilateral hip joint synovial osteochondromatosis case, Mackenzie et al. (4) presented Fatih Bagcier, Ayhan Kul, Emine Esra Ergul, Akin Erdal

Traumatic Arthrotomy with Pneumarthrosis on Plain Radiograph of the Knee

An eight-year-old boy presented to the emergency department (ED) with a 2cm-long laceration over the prepatellar region of his left knee after falling over and cutting his knee on broken glass. Physical examination demonstrated the laceration breached the dermis but otherwise there was no obvious defect in the deep fascial layer. He had a free range of motion of his knee and clinically his extensor mechanism was intact; however, a plain lateral radiograph showed that he had pneumarthrosis of his knee joint. Within six hours of injury the wound was formally explored in the operating room and a small breach in the knee capsule was found. The wound edges were debrided, the knee joint irrigated and the skin closed primarily. Following surgery he received 24 hours of antibiotic coverage with a first-generation cephalosporin. Gas in the joint or “pneumarthrosis” in the context of trauma is not uncommon around superficial joints such as the knee and indicates that there is a penetrating wound with intra-articular extension.1 This implies that the joint has been inoculated with bacteria and pyoarthrosis is possible if not managed appropriately.1 The standard treatment for a traumatic arthrotomy is antibiotic coverage and prompt surgical debridement in the operating room with lavage of the soft tissues and joint.2 In the absence of gross contamination primary closure can be performed.2 Even innocuous-looking lacerations adjacent to or overlying superficial joints can lead to a traumatic arthrotomy. Plain radiographs should be obtained and a high suspicion for intra-articular extension maintained. For lacerations around superficial joints there should be a low threshold for exploring and washing these wounds out in the operating room rather than closing primarily in the ED.

A Less Invasive Approach of Medial Meniscectomy in Rat: A Model to Target Early or Less Severe Human Osteoarthritis

Objectives: The existing medial meniscectomy (MMx) procedure in rodents involves transection of MCL and wide opening of the knee capsule followed by meniscus transection that results into articular cartilage degeneration and causes significant changes in subchondral bone at specific post-MMx period. These animals serve as experimental osteoarthritis (OA) models. Structurally, knee is very complex. There may be a need to uncouple articular cartilage degenerative changes from subchondral bone degenerative changes in experimental OA models. Therapeutical drugs/agents, designed to treat articular cartilage degenerative changes of OA knee, may not be effective to treat subchondral bone degenerative changes or vice versa. The purpose of the study was to modify the existing MMx procedure to a less invasive procedure so that it causes only articular cartilage degenerative OA changes and no subchondral bone changes. This will serve as an early OA model to target degenerative changes in articular cartilage in human. Methods: Ten 8-9 weeks old male athymic nude rats underwent less invasive MMx on right knee; the left knee served as unoperated control. The surgery involved no transection of MCL and opening of knee capsule wide. The medial meniscus was pulled out from a slit made on the medial aspect of the knee capsule, and was transected. At 10 weeks post-MMx, animals were sacrificed and knees were assessed. Results: There was no significant alteration in bone strength parameters (BV/TV, Tb.Th, Tb.Sp, Tb.N, Tb.Pf, cortical wall thickness) in subchondral bone in the less invasive MMx knee as analyzed by μCT. X-ray radiography did not indicate the presence of any osteophyte at the knee margins. On the other hand, the less invasive MMx caused degenerative changes in articular cartilage as follows: fibrillation and thinning in the medial tibia; narrowing of medial knee joint; reduced proteoglycans shown by safranin-O staining; decreased metachromasia by PSR staining; alteration in collagen fibril thickness under cross-polarization light. Immunohistochemical expression was reduced (COL-II, aggrecan), increased (NITEGE, Col2-3/4m, COL-X, and MMP13) or imbalanced (lubricin) in articular cartilage thickness of less invasive MMx knee. Conclusion: The less invasive MMx procedure, in rat, can be a model for early or less severe human OA due to articular cartilage degenerative changes only and with no subchondral bone degenerative changes in the knee synovial joint. The therapeutical drugs/agents designed to repair articular cartilage may be suitable for this model and may lead to treatment of early or less severe human OA.

The Nerves of the Adductor Canal and the Innervation of the Knee: An Anatomic Study.

Adductor canal block contributes to analgesia after total knee arthroplasty. However, controversy exists regarding the target nerves and the ideal site of local anesthetic administration. The aim of this cadaveric study was to identify the trajectory of all nerves that course in the adductor canal from their origin to their termination and describe their relative contributions to the innervation of the knee joint. After research ethics board approval, 20 cadaveric lower limbs were examined using standard dissection technique. Branches of both the femoral and obturator nerves were explored along the adductor canal and all branches followed to their termination. Both the saphenous nerve (SN) and the nerve to vastus medialis (NVM) were consistently identified, whereas branches of the anterior obturator nerve were inconsistently present. The NVM contributed significantly to the innervation of the knee capsule, through intramuscular, extramuscular, and deep genicular nerves. The SN had a relatively more modest contribution through superficial infrapatellar and posterior branches as well as contributing to the origin of the deep genicular nerves. The results suggest that both the SN and NVM contribute to the innervation of the anteromedial knee joint and are therefore important targets of adductor canal block. Given the site of exit of both nerves in the distal third of the adductor canal, the midportion of the adductor canal is suggested as an optimal site of local anesthetic administration to block both target nerves while minimizing the possibility of proximal spread to the femoral triangle.

Significance of medial patello-femoral ligament in support of patella stability: features of anatomy and biomechanics

The purpose of the study - anatomical and biomechanical substantiation of medial patellofemoral ligament (MPFL) reconstruction in cases of recurrent patella dislocation. Material and methods. Anatomical studies were performed in 27 fresh frozen cadaver knees. Biomechanical study was made using video capture system with 5 specimens of the knee. In the first stage we examined the lateral displacement of the patella when the knee was flexing, and in the second - isometric properties of the MPFL. Results. In all cases MPFL was found between the knee capsule and the superficial fascia. In 6 (22.2%) cases singlebundle structure was revealed, in 14 (51.8%) - two-bundle and in 2 (7.4%) - three-bundle structure. In 2 (7.4%) knee joints MPFL was presented in one thinned bundle, attached to the upper third of the patella. The degree of the MPFL isometry was indicated by changing in the distance between the optical markers located in the regions of attachment of MPFL ligament. For all of the knees this distance had reached 58.3±1.2 mm tibia in knee flexion at 20°; 57.8±,4 mm - when flexed by 30°; 56.9±1,3 mm - at 45°; 56.8±1,3 mm - at 60° of flexion and 53.0±0,7 mm - at 90°. Conclusion. There are several variants of MPFL anatomical structure, and in most cases it has two bundles oriented to the medial surface of the knee from posterior to anterior and from proximal to distal directions. MPFL has a streak of isometry, as a normal characteristic of each anatomical ligament and this isometry must be followed in MPFL reconstruction in case of recurrent patella dislocation.

Auxiliary proteins that facilitate formation of collagen-rich deposits in the posterior knee capsule in a rabbit-based joint contracture model.

Post-traumatic joint contracture is a debilitating consequence of trauma or surgical procedures. It is associated with fibrosis that develops regardless of the nature of initial trauma and results from complex biological processes associated with inflammation and cell activation. These processes accelerate production of structural elements of the extracellular matrix, particularly collagen fibrils. Although the increased production of collagenous proteins has been demonstrated in tissues of contracted joints, researchers have not yet determined the complex protein machinery needed for the biosynthesis of collagen molecules and for their assembly into fibrils. Consequently, the purpose of our study was to investigate key enzymes and protein chaperones needed to produce collagen-rich deposits. Using a rabbit model of joint contracture, our biochemical and histological assays indicated changes in the expression patterns of heat shock protein 47 and the α-subunit of prolyl 4-hydroxylase, key proteins in processing nascent collagen chains. Moreover, our study shows that the abnormal organization of collagen fibrils in the posterior capsules of injured knees, rather than excessive formation of fibril-stabilizing cross-links, may be a key reason for observed changes in the mechanical characteristics of injured joints. This result sheds new light on pathomechanisms of joint contraction, and identifies potentially attractive anti-fibrotic targets.

Temporal gene expression profiling of the rat knee joint capsule during immobilization-induced joint contractures.

BackgroundContractures of the knee joint cause disability and handicap. Recovering range of motion is recognized by arthritic patients as their preference for improved health outcome secondary only to pain management. Clinical and experimental studies provide evidence that the posterior knee capsule prevents the knee from achieving full extension. This study was undertaken to investigate the dynamic changes of the joint capsule transcriptome during the progression of knee joint contractures induced by immobilization. We performed a microarray analysis of genes expressed in the posterior knee joint capsule following induction of a flexion contracture by rigidly immobilizing the rat knee joint over a time-course of 16 weeks. Fold changes of expression values were measured and co-expressed genes were identified by clustering based on time-series analysis. Genes associated with immobilization were further analyzed to reveal pathways and biological significance and validated by immunohistochemistry on sagittal sections of knee joints.ResultsChanges in expression with a minimum of 1.5 fold changes were dominated by a decrease in expression for 7732 probe sets occurring at week 8 while the expression of 2251 probe sets increased. Clusters of genes with similar profiles of expression included a total of 162 genes displaying at least a 2 fold change compared to week 1. Functional analysis revealed ontology categories corresponding to triglyceride metabolism, extracellular matrix and muscle contraction. The altered expression of selected genes involved in the triglyceride biosynthesis pathway; AGPAT-9, and of the genes P4HB and HSP47, both involved in collagen synthesis, was confirmed by immunohistochemistry.ConclusionsGene expression in the knee joint capsule was sensitive to joint immobility and provided insights into molecular mechanisms relevant to the pathophysiology of knee flexion contractures. Capsule responses to immobilization was dynamic and characterized by modulation of at least three reaction pathways; down regulation of triglyceride biosynthesis, alteration of extracellular matrix degradation and muscle contraction gene expression. The posterior knee capsule may deploy tissue-specific patterns of mRNA regulatory responses to immobilization. The identification of altered expression of genes and biochemical pathways in the joint capsule provides potential targets for the therapy of knee flexion contractures.