A computer-based model of the knee was used to study forces in the cruciate ligaments induced by co-contraction of the extensor and flexor muscles, in the absence of external loads. Ligament forces are required whenever the components of the muscle forces parallel to the tibial plateau do not balance. When the extending effect of quadriceps exactly balances the flexing effect of hamstrings, the horizontal components of the two muscle forces also balance only at the critical flexion angle of 22 degrees. The calculations show that co-contraction of the quadriceps and hamstring muscles loads the anterior cruciate ligament from full extension to 22 degrees of flexion and loads the posterior cruciate at higher flexion angles. In these two regions of flexion, the forward pull of the patellar tendon on the tibia is, respectively, greater than or less than the backward pull of hamstrings. Simultaneous quadriceps and gastrocnemius contraction loads the anterior cruciate over the entire flexion range. Simultaneous contraction of all three muscle groups can unload the cruciate ligaments entirely at flexion angles above 22 degrees. These results may help the design of rational regimes of rehabilitation after ligament injury or repair

Orientation of the native acetabular plane as defined by the transverse acetabular ligament (TAL) and the posterior labrum was measured intra-operatively using computer-assisted navigation in 39 hips. In order to assess the influence of alignment on impingement, the range of movement was calculated for that defined by the TAL and the posterior labrum and compared with a standard acetabular component position (abduction 45°/anteversion 15°). With respect to the registration of the plane defined by the TAL and the posterior labrum, there was moderate interobserver agreement (r = 0.64, p < 0.001) and intra-observer reproducibility (r = 0.73, p < 0.001). The mean acetabular component orientation achieved was abduction of 41° (32° to 51°) and anteversion of 18° (−1° to 36°). With respect to the Lewinnek safe zone (abduction 40° ±10°, anteversion 15° ±10°), 35 of the 39 acetabular components were within this zone. However, there was no improvement in the range of movement (p = 0.94) and no significant difference in impingement (p = 0.085). Alignment of the acetabular component with the TAL and the posterior labrum might reduce the variability of acetabular component placement in total hip replacement. However, there is only a moderate interobserver agreement and intra-observer reliability in the alignment of the acetabular component using the TAL and the posterior labrum. No reduction in impingement was found when the acetabular component was aligned with the TAL and the posterior labrum, compared with a standard acetabular component position

An operation using either the medial or the lateral meniscus to effect the late repair of torn cruciate ligaments is described. Forty-three patients under fifty years of age who were unable to return to their work because of severe joint laxity have been treated in this way and reviewed after one to thirty years. Sagittal stability was measured by a special apparatus, and a comparison was made between normal knees and affected knees before and after operation. The review of forty-five knees showed normal stability in thirty-one, slight instability in twelve and no improvement in two. Forty-one patients had returned to their former work: twenty-two complained of instability when tired; all had pain-free joints. The use of a meniscus for the reconstruction of either cruciate ligament is considered to be simple, safe and effective

We report 18 cases of pain and tenderness in the mid-part of the patellar ligament in athletes. The condition may be disabling, but it responds to surgery. Ultrasound and CT scans were positive in all 17 confirmed cases, but ultrasound gave a better distinction between the cysts, granulation tissue, metaplasia, mucoid degeneration and congenital defects found at operation

1. Forty-two previously asymptomatic patients presenting with a recent rupture of the lateral ligament of the ankle, and twenty similar patients with a simple sprain of this ligament, have been followed for one year. The physical and radiological findings upon the completion of treatment have been related to functional instability of the foot one year later. 2. Persistent mechanical varus instability of the talus in the ankle mortise was a possible cause of functional instability one year after injury in four (or perhaps six) patients. 3. Adhesion formation was a possible cause of functional instability in one patient. 4. Seventeen patients finally displayed no clinical or radiological abnormality after injury, but noted functional instability of the foot one year later. 5. It is concluded that the pathological process which is usually responsible for functional instability of the foot after a lateral ligament injury is at present unknown

We have studied the kinematics of the knee in the sagittal plane, using a four-bar linkage as model, and assuming that a "neutral fibre" in each ligament remains isometric throughout flexion. We devised a computer program to calculate the distance separating any pair of points, one on each bone, for various cruciate attachments at various angles of flexion. The parameters for the linkage in four cadaveric knees were obtained by marking the centre of attachment of the cruciate ligaments with tacks and taking lateral radiographs. The movements of the bones were then calculated, in the computer model, for various attachments of "replacement" ligament fibres, the distance between the attachment sites being plotted against the angle of flexion. It was then possible to define zones around the isometric attachment points within which changes in length would be predictable. Our results show that the position of the femoral sites of attachment of both anterior and posterior cruciate replacement was more critical than that of the tibial attachments

Achieving deep flexion after total knee replacement remains a challenge. In this study we compared the soft-tissue tension and tibiofemoral force in a mobile-bearing posterior cruciate ligament-sacrificing total knee replacement, using equal flexion and extension gaps, and with the gaps increased by 2 mm each. The tests were conducted during passive movement in five cadaver knees, and measurements of strain were made simultaneously in the collateral ligaments. The tibiofemoral force was measured using a customised mini-force plate in the tibial tray. Measurements of collateral ligament strain were not very sensitive to changes in the gap ratio, but tibiofemoral force measurements were. Tibiofemoral force was decreased by a mean of 40% (. sd. 10.7) after 90° of knee flexion when the flexion gap was increased by 2 mm. Increasing the extension gap by 2 mm affected the force only in full extension. Because increasing the range of flexion after total knee replacement beyond 110° is a widely-held goal, small increases in the flexion gap warrant further investigation

Objectives. Because posterior cruciate ligament (PCL) resection makes flexion gaps wider in total knee replacement (TKR), preserving or sacrificing a PCL affects the gap equivalence; however, there are no criteria for the PCL resection that consider gap situations of each knee. This study aims to investigate gap characteristics of knees and to consider the criteria for PCL resection. Methods. The extension and flexion gaps were measured, first with the PCL preserved and subsequently with the PCL removed (in cases in which posterior substitute components were selected). The PCL preservation or sacrifice was solely determined by the gap measurement results, without considering other functions of the PCL such as ‘roll back.’. Results. Wide variations were observed in the extension and flexion gaps. The flexion gaps were significantly larger than the extension gaps. Cases with 18 mm or more flexion gap and with larger flexion than extension gap were implanted with cruciate retaining component. A posterior substitute component was implanted with the other cases. Conclusions. In order to make adequate gaps, it is important to decide whether to preserve the PCL based on the intra-operative gap measurements made with the PCL intact. Cite this article: Bone Joint Res 2014;3:95–100

A 35-year-old man was seen with pain in the back of the knee. MRI showed a mass in the anterior cruciate ligament. Biopsy indicated mucoid degeneration. Arthroscopic resection of the ligament was carried out, with relief of symptoms

We present a case of disruption of the posterolateral corner of the knee with avulsion of the tendon of biceps femoris. Repair and reconstruction included an allogenic tendon graft to replace the posterior cruciate ligament. Surgery was followed by a complete common peroneal nerve palsy. Revision surgery revealed that the nerve had been displaced anteriorly by avulsion of the biceps tendon and the tendon graft encircled it. Release of the nerve restored normal function at five months

1. Seventeen cases of knee injury are described in which the predominant lesion was rupture of the posterior cruciate ligament. Seven were treated conservatively and ten by surgical repair. 2. Most cases occurred in motor cyclists. 3. The extent of the rupture should be determined by examination under anaesthesia. 4. Early surgical repair is indicated for complete rupture. 5. An effective method of repair is described

We set up a trial to test whether the KT1000 arthrometer would give consistent measurements of anteroposterior laxity when used by the same and different examiners on the knees of the same subjects on the same day. The results showed substantial inter- and intra-examiner variation in the measurements both of absolute displacement in single knees and of side-to-side differences between pairs of knees. This casts doubt on the reliability of the instrument when used to compare the results of different techniques for reconstructing injured cruciate ligaments

We have assessed the biomechanical properties of a 'double-bundle' prosthetic ligament replacing the anterior cruciate in cadaver knees. We compared the results with those of single bundle 'over-the-top' and 'through-the-condyle' techniques, performing anterior drawer tests at 20 degrees and 90 degrees knee flexion. The over-the-top reconstruction gave better anteroposterior stability at 20 degrees, while the through-the-condyle repair was more stable at 90 degrees. The double-bundle reconstruction gave practically normal anterior stability at both 20 degrees and 90 degrees

We dissected 60 shoulders to demonstrate the anatomy of the coracohumeral ligament. The role of this structure in clinical problems of the shoulder is discussed

1. A case of disruption of patellar ligament is described. 2. An association with previous steroid infiltration is present in this case

We treated 39 knees with chronic deficiency of the anterior cruciate ligament by reconstruction using the ABC carbon and polyester prosthetic ligament; 31 (79.5%) were reviewed at an average follow-up of 34 months. There had been four complete failures requiring revision. The remaining 27 were studied in detail. On the Lysholm rating, only 11 knees (41%) had good results with a score of over 76. The mean anterior drawer movement was reduced from 7.6 mm before operation to 5.8 mm at review. The mean difference from the opposite uninjured knee was 3.9 mm before operation, 1 mm (in 21 patients) at mean follow-up of 7.4 months and 2.5 mm (in 27 patients) at 34 months, indicating progressive loss of effect. In our opinion the results are unsatisfactory: we do not recommend the use of this prosthetic ligament

We studied the stabilising effect of prosthetic replacement of the radial head and repair of the medial collateral ligament (MCL) after excision of the radial head and section of the MCL in five cadaver elbows. Division of the MCL increased valgus angulation (mean 3.9 ± 1.5°) and internal rotatory laxity (mean 5.3 ± 2.0°). Subsequent excision of the radial head allowed additional valgus (mean 11.1 ± 7.3°) and internal rotatory laxity (mean 5.7 ± 3.9°). Isolated replacement of the radial head reduced valgus laxity to the level before excision of the head, while internal rotatory laxity was still greater (2.8 ± 2.1°). Isolated repair of the MCL corrected internal rotatory laxity, but a slight increase in valgus laxity remained (mean 0.7 ± 0.6°). Combined replacement of the head and repair of the MCL restored stability completely. We conclude that the radial head is a constraint secondary to the MCL for both valgus displacement and internal rotation. Isolated repair of the ligament is superior to isolated prosthetic replacement and may be sufficient to restore valgus and internal rotatory stability after excision of the radial head in MCL-deficient elbows

We studied 57 patients with isolated lunotriquetral injuries treated by arthrodesis, direct ligament repair, or ligament reconstruction. The outcomes were compared by using written questionnaires, the Disabilities of the Arm, Shoulder and Hand (DASH) score, range of movement, strength, morbidity and rates of reoperation. Isolated lunotriquetral injury was confirmed by arthroscopy or arthrotomy. The mean age of the patients was 30.7 years (15.4 to 53.7) and the injuries were subacute or chronic in 98.2%. Eight patients underwent lunotriquetral reconstruction using a distally-based strip of the tendon of extensor carpi ulnaris, 27 had lunotriquetral repair and 22 had lunotriquetral arthrodesis. The mean follow-up was 9.5 years (2 to 22). The probability of remaining free from complications at five years was 68.6% for reconstruction, 13.5% for repair, and less than 1% for arthrodesis. Of the lunotriquetral arthrodeses, 40.9% developed nonunion and 22.7% developed ulnocarpal impaction. The probability of not requiring further surgery at five years was 68.6% for reconstruction, 23.3% for repair and 21.8% for arthrodesis. The DASH scores for each group were not significantly different. Objective improvements in strength and movement, subjective indicators of pain relief and satisfaction were significantly higher in the lunotriquetral repair and reconstruction groups than in those undergoing arthrodesis

Ten cases of complete rupture of the collateral ligaments of the metacarpophalangeal finger joints are reported. The nature of this injury, the pre-operative morbidity and the intra-operative pathology are analysed. In all cases surgery was performed with satisfactory results. Operation is indicated for joint stability, grip and pinch strength, pain control and early functional recovery

1. Two cases of deposition of calcium in the medial ligament of the knee are described. Pain was a prominent feature in both. 2. A review of the literature suggests this is an uncommon condition. 3. The condition closely resembles supraspinatus calcification, and the etiology is probably similar. 4. Both cases were treated by operation, with complete relief of symptoms