A new apparatus and technique of syndesmosis fixation is tested in a prospective clinical study. Buttons on both sides of the ankle anchor a strong suture under tension following syndesmosis reduction. This syndesmosis suture acts like a tightrope when under tension. Implantation is simple with a minimally invasive technique, as the medial side is not opened. It allows physiological micromotion whilst resisting diastasis, does not require routine removal, and allows patients to weight-bear earlier.

Sixteen patients with Weber C ankle fractures with a syndesmosis diastasis underwent suture-button fixation and the results compared to 16 consecutive patients with syndesmosis screw fixation. Patients were, in effect, quasi-randomised according to surgeon preference. Mean A,O,F,A,S, ankle scores were significantly better in the suture-button group at three months post-op (91 vs 80, p=0.01, unpaired t-test) and at twelve months (93 vs 83, p=0.04, unpaired t-test). Return to work was also significantly faster (2.6 months vs 4.6 months, p=0.02, unpaired t-test). No suture-buttons required implant removal. Axial CT scanning at three months showed implants to be intact with maintenance of reduction, as compared to the uninjured contralateral side.

Suture-button syndesmosis fixation is simple, safe and effective. It has shown improved outcomes and faster rehabilitation, without needing routine removal. Although the apparatus design may undergo further refinement, we believe this technique will become the treatment of choice in Weber C ankle fractures with a syndesmosis injury.

Introduction A new technique of ankle syndesmosis fixation is proposed. Buttons are placed on both sides of the ankle, connected by a strong non-absorbable suture. The technique is simple and minimally invasive: a medial incision is not required. It resists diastasis whilst allowing physiological micromotion and does not require routine removal.

Methods The technique was tested on a cadaver model of a Maisonneuve injury under increasing torque loads. Sixteen embalmed cadaver legs were randomised to receive suture-button fixation or four-cortical 4.5 mm syndesmosis screw fixation. A prospective clinical study involving 16 patients with Weber C fractures and syndesmosis diastasis is presented. They underwent suture-button fixation and the results were compared to 16 consecutive patients with syndesmosis screw fixation.

Results In the cadaver study, both groups had similar rates of diastasis following torque loading. However, the suture-button did give a more consistent performance: standard deviations were significantly lower (p=0.001) than the screw group. In the clinical study, both groups were evenly matched as regards patient age, male: female ratio, and fracture patterns. Mean AOFAS ankle outcome scores at three months were significantly better in the suture-button group (91 versus 82, p=0.01). No suture-button patients required implant removal. They had a faster return to work compared to the screw group (three months versus five months). Axial CT scanning performed at three months post-op showed all implants to be intact with no loss of reduction.

Conclusions Suture-button syndesmosis fixation is simple, safe, effective and physiological. It has shown improved outcomes and faster rehabilitation, without needing routine removal. It may become the treatment of choice in Weber C ankle fractures with a syndesmosis diastasis.

In relation to the conduct of this study, one or more the authors have received, or are likely to receive direct material benefits.

Aims: A new technique of syndesmosis fixation is proposed; placing buttons on both sides of the ankle, without opening the medial side, connected by a strong non-absorbable suture. We tested this against syndesmosis screw fixation in a cadaver model of a Maisonneuve injury and subsequently in a prospective clinical study. Methods: 16 cadaver legs were randomised to have suture-button or syndesmosis screw fixation and tested under torque loading. In the clinical study, 16 patients with a syndesmosis diastasis underwent suturebutton fixation and the results compared to 16 patients with syndesmosis screw fixation. Results: In the cadaver study, both groups had similar rates of diastasis, although the suture-button did give a more consistent performance: standard deviations were significantly lower (p=0.001). In the clinical study, mean A.O.F.A.S. scores at 3 months were significantly better in the suturebutton group (91 vs 82, p=0.01). No suture-button implants required removal, compared to 13/16 of the screw group (p=0.001). Conclusions: Suture-button syndesmosis fixation is simple, safe and physiological. Biomechanically it performs at least as well as screw fixation. Clinically it has shown improved outcomes, without needing routine removal. It may become the treatment of choice in syndesmosis injuries.

Injury to the infrapatellar branch of the saphenous nerve has been reported as a complication of arthroscopic examination and surgery of the knee. This can result in altered sensation on the anterolateral aspect of the knee, reflex sympathetic dystrophy and, occasionally, severe deafferentation pain. The aim of this cadaveric study was to delineate the course of the infrapatellar branch as it passes across the anterior aspect of the knee and identify potential safe areas for blind puncture at arthroscopy. The risk of damage to the nerve branch from the various open incisions used for orthopaedic surgery of the knee is also discussed.

The distribution of the infrapatellar branch was studied in both lower limbers of eleven cadavers (22 specimens). Two patterns of nerve distribution could be described in relation to its path across the proximal margin of the tibia. In 28% of examined cadavers, the infrapatellar branch of the saphenous nerve traverses the patellar tendon and runs laterally without ever crossing over the tibia. In the remaining 72% the infrapatellar branch crossed the proximal margin of the tibia prior to crossing the patellar tendon. Using the interior pole of the patella as a landmark, our results indicated that blind puncture is safe within an approximate wedge-shaped area ranging from 10mm inferior and 30mm medial to the inferior pole up to a level 10mm superior and 50mm medial to the inferior pole of the patella. The incidence of injury to this nerve can be reduced by clarifying the distribution of the infrapatellar nerve branch in relation to palpable landmarks.

Introduction: The infrapatellar fat pad was first described in 1904 by Albert Hoffa. Sometimes disregarded, it is apparent that the infrapatellar fat pad is of importance to knee joint function as fat at this site is only lost in severely emaciated individuals. Also, recent MRI studies have described various pathological changes affecting the fat pad. This study examined the anatomy of the infrapatellar fat pad in relation to knee symptoms and surgical approaches.

Materials and Methods: 8 preserved knees were dissected via semicircular parapatellar incisions extending from the tibial tubercle to the superior patellar border and including the quadriceps muscle 13 cm above the superior border of the patella. The synovial membrane of the joint and the ligamentum mucosum were divided and the tibial tubercle was then excised. The resultant tissue complex was removed and the fat pad dissected away from surrounding structures. The appearance, volume and presence of any clefts in the pad were recorded. The cadaveric dissections were then compared to direct observation of the fat pad during total knee replacement, during arthroscopy and on MR imaging.

Results: The infrapatellar fat pad was found to be present in all cases. It had a consistent shape consisting of a central mass with medial and lateral extensions. The ligamentum mucosum was attached to the intercondylar notch of the femur in all cases and measured an average of 15.7mm at its base. A horizontal cleft was found in 6 cases and a vertical cleft was found in 7 cases. Both have been previously noted. A tag extended superiorly from the posterior aspect of the fat pad in 7 cases. The volume of the fat pad had quite a large range among individual cadavers (average volume was 24 ml, range: 12–36ml). The intra-individual variation was smaller with an average difference of 4ml (range:2.7ml) between knees.

Discussion: The infrapatellar fat pad has been implicated in a wide variety of conditions affecting the knee joint. It has been shown to be involved in arthofibrosis of the knee following surgery, patellar tendonitis, formation of intra-articular fibrous bands, and a site of an ossifying chondroma. It seems that fat pad pathology is usually secondary to other knee joint pathology and primary involvement is rare. The presence of clefts in the fat pad is of importance as a distended cleft may mimic an abnormality and an abnormality in the cleft may be overlooked on imaging of the knee joint. The appearance of the fat pad on direct visualisation in the living person presented a fat pad with a more globular appearance than that seen in the cadaver. The clefts were clearly visualised on MRI.

Conclusion: The infrapatellar fat pad is a structure that is consistently present in the knee joint. It consists of a central body with medial and lateral and medical extensions. It usually contains a vertical cleft located superiorly and a horizontal cleft located inferiorly as well as a tag of fat extending superiorly, which forms the roof of the vertical cleft. The infrapatellar fat pad is attached to the intercondylar notch of the femur by the ligamentum mucosum and is firmly anchored to the patella by dense fibrous tissue.

The meniscofemoral ligaments (MFL) of the knee have both functional and clinical importance, but have been poorly described. We examined 42 human cadaver knees: there was at least one MFL in every joint and both ligaments were present in 27. The anterior MFL was present in the knees in all 18 males and in 17 of the 24 females. The posterior MFL was present in 16 males and 22 females. Measurement of the ligaments showed that they were of significant size. The mean midpoint width for the anterior MFL was 5.09 ± 1.41 mm in males and 2.99 ± 1.29 mm in females. The mean width of the posterior MFL was 5.48 ± 2.13 mm in males and 3.79 ± 2.56 mm in females. The average length of the anterior MFL was 27.09 ± 2.15 mm in males and 24.38 ± 3.39 mm in females, and the posterior MFL was 31.13 ± 2.54 mm and 27.59 ± 3.74 mm, respectively. There were anatomical variations in 16 (38%) knees (62.5% female, 37.5% male), more commonly in the posterior ligament.

We conclude that the meniscofemoral ligaments are anatomically and probably functionally important structures in the human knee.